Excipients in drug delivery systems: A comprehensive review of approved inactive ingredients for human ophthalmic formulations

Abstract
Pharmaceutical excipients, commonly known as inactive ingredients, encompass any substance aside from the active ingredient that fulfills a distinct and vital role in a formulation. Their purpose is to enhance specific characteristics, whether associated with the performance of the formulation or aspects related to patient comfort, safety, and acceptability. Because of the limited toxicity studies provided, and the several allergic and toxic side effects that have been reported throughout the years, it is not trivial for the regulatory agencies to approve inactive ingredients for human use. In general, excipients are approved within good manufacturing practices (GMPs) when they undergo analysis of the formulation as a whole, not the standalone substance. However, there is a lack of updated information regarding this subject, given that only the American Food and Drug Administration (FDA) provides a complete list describing the inactive ingredients that are currently approved in drug products for human use. Here, we aimed to provide an overview of key excipients approved by the FDA for ophthalmic use in humans, focusing on their functional roles in ophthalmic formulations, particularly eye drops, and the regulatory requirements involved in these ingredients approval.
Introduction
Different obstacles, whether anatomical or physiological, are responsible for making the treatment of ocular diseases a challenging task. At first, these barriers play a crucial role in protecting the eye against microorganisms, toxins and the systemic circulation; however, these mechanisms are a drawback when it comes to delivering drugs and molecules at therapeutic levels to specific targets within the different ocular tissues [1], [2], [3], [4].
Ophthalmic preparations are designed to reach target ocular tissues in therapeutic, prophylactic or palliative doses via different pharmaceutical forms. In general, these formulations can be administered on the anterior surface of the eye, intraocularly, periocularly, or associated to ophthalmic devices [5]. While intraocular and periocular administrations occur via injections to treat diseases and conditions mainly of the posterior segment of the eye, topical administration is the primary method of drug delivery to the anterior segment [6]. Topically administered drugs in the form of solutions, suspensions, emulsions, gels and ointments are the most common ophthalmic formulations on the market [7], especially because of their ease of manufacturing, low cost and low side effects [8]. Water-soluble drugs are typically delivered via instillation of an aqueous solution, while water-insoluble drugs are usually administered topically as ointments, gels or aqueous suspensions [9]. It is no surprise though that over 90 % of these topical formulations account for eye drops [6].
Eye drop solutions show particular features such as being non-invasive, and easy to deliver drugs to the anterior segment of the eye [10], which contributes for patient compliance. Nevertheless, the major drawbacks of drop instillation are its short residence time and low bioavailability; only about 20 % of the original dose remains in the precorneal segment of the eye, due to significant precorneal drug loss through blinking, tear renewal, tearing and systemic elimination [11], [12]. This is why an increase in the retention time and enhanced corneal permeation are necessary for an effective drug distribution in the eye [13], [14], [15], [16]. Thus, despite being a more comfortable via of administration for the patient, these drawbacks make it necessary to improve the number of drop instillation throughout the day, which can lead to incomplete adherence to the treatment by the patient. In most cases suspensions and emulsions try to overcome the low solubility of hydrophobic drugs, and, as a consequence, improve their bioavailability. Generally, suspensions consist of a dispersion of finely divided particles of < 10 µm size of an insoluble drug, and show greater contact time due to drug retention in the conjunctival cul-de-sac. However, larger particles can cause blurred vision and discomfort to the patient, besides being relatively unstable and exhibiting complex quality issues, such as dose uniformity (MOROFUJI, 2024). Emulsions, on the other hand, are more stable systems thanks to the presence of surfactants that allow the coexistence of two different phases in the same system. One of the ways of classifying emulsions is according to the composition of their internal and external phases, being the oil-in-water (O/W) emulsion less irritant to the eye [17], [18], [19], [20].
Ointments are semisolid preparations with bases of mineral oil or petrolatum, typically forming either a monophasic vehicle (a single continuous phase) or a biphasic system (an oil-and-water emulsion). These formulations also slow down the elimination of the drug and increase the corneal residence time. Although generally non-irritating to the eye, ointments can blur vision, causing patient discomfort and reducing compliance [9], [21].
Gels are also common formulations that show better precorneal residence time compared to liquid eye drops. They are three-dimensional network structures, formed by cross-linked polymers or a colloidal network immersed in a fluid [22], [23]. Hydrogels constitute a class of gels that can absorb and retain water, making them well tolerated compared to the other conventional formulations. Nevertheless, the administration of gel eye drops can cause blurred vision, tearing and crusting on the eyelids [22], which lead to the development of drops that undergo gelation after instillation. This process, called in situ sol–gel transition, occurs with polymers sensitive to external stimuli, and contribute to better convenience of administration and increased residence time of drugs [23], [24], [25], [26].In this scenario, novel drug delivery systems emerge as a potential alternative to hand over molecules into the eye in a modulated fashion, and they are designed to overcome ocular barriers, increase residence time of the drug in the tissue, enhance drug bioavailability and stability, and reduce dosing frequency [27], [28], [29]. These aspects contribute not only to better patient compliance to the treatment, but also to mitigate the broader socio-economic consequences of ocular diseases [30].
In general, delivery systems should be safe, inert and effective [31]. Different technologies and materials have already given form to various types of formulations that comprise devices, such as implants and microneedles, and micro and nanotechnology applied to formulations that include capsules, particles, gels, liposomes, micelles, suspensions and emulsions, among others [31], [32], [33], [34], as indicated in Fig. 1.

The composition of these novel systems varies according to the type of formulation (polymeric, lipidic, biodegradable or non-biodegradable, for instance), the desired performance characteristics and the compatibility with the ocular tissues [35]. While the drug, also called active pharmaceutical ingredient (API), is responsible for the therapeutic effect of the formulation, all the other components of the delivery systems fulfill a specific role in the formulation, and they’re called pharmaceutical excipients, or inactive ingredients.
Pharmaceutical excipients refer to any substance employed in the creation or composition of a final pharmaceutical dosage, apart from the active substance. These excipients perform several important functions that may include protection, support or enhancement of stability and bioavailability of the active molecule; ease of the system production process; additional qualities related to the overall safety and efficacy of the entire medication throughout its storage and usage; and patient acceptability, in a way that the active drug substance can be presented in a form that is visually pleasing, palatable and easy to administer [36], [37], [38], [39]. In general, inactive ingredients play a role in different formulations as diluents, buffers, preservatives, surfactants, and solubility, penetration and viscosity enhancers, among others [40]. Examining the excipient, including factors such as reactive impurity sources and variability, and comprehending its influence on the stability of the drug product is crucial when creating a resilient pharmaceutical formulation [41].
Information regarding active and inactive ingredients is commonly described in pharmacopeias. A pharmacopeia is an official compendium, published by national and international pharmacological authorities, that specifies the quality and purity standards of drugs, excipients and other medicinal products. It serves as a reference for healthcare professionals involved in the development and dispensing of pharmaceutical products. It also dictates the physical–chemical properties of these substances, as well as the required methods of analysis and the acceptable values of dosage, impurities and every other parameter important for attesting the safety and efficacy of the product [42], [43].
Examples of well-known and internationally recognized compendia are the United States Pharmacopeia (USP), the European Pharmacopeia (Ph.Eur.) and the British Pharmacopeia (BP), despite the other representatives from various countries and regions. Regardless of listing and describing the already known excipients, these compendia lack information about regulatory aspects, including their inherent functionality, approval for human use, and the specific circumstances under which they are permitted or prohibited [44], [45], [46].

Instead, regulatory agencies play the role of establishing and enforcing regulations and standards that, among other competences, define which medicaments are approved for human use in the country or countries where those agencies operate. World Health Organization (WHO), Food and Drug Administration (FDA) and European Medicines Agency (EMA) are well-known and prestigious examples of regulatory agencies. Yet, only FDA, the American agency, provides an extensive list describing all the inactive ingredients which are currently approved in drug products for human use. These distinctions are summarized in Fig. 2.
In this review we aimed to categorize and briefly discuss the key functional roles of FDA-approved excipients in ophthalmic preparations, offering practical information for formulation development intended for human use.We focused onapproved excipients for ophthalmic, intraocular or intravitreal applications according to the FDA Inactive Ingredients List. The original list can be found at the electronic address https://www.accessdata.fda.gov/scripts/cder/iig/index.cfm. Here, this list was adapted to include the most relevant information, such as ingredients names, CAS numbers, routes of administration, and dosage forms. Additionally, the pharmacotechnical applications of each excipient are specified and summarized in Table 1.
Given the importance of eye drops in treating various eye conditions, particularly those affecting the anterior segment, special attention was given to the categories of inactive ingredients commonly used in these formulations.
2. Key functional categories of excipients

Pharmaceutical excipients play crucial functional roles, such as influencing the bioavailability and solubility of APIs, enhancing their stability within the dosage form, regulating osmolarity and/or pH in liquid formulations, and preventing dissociation and aggregation. The incorporation of pharmaceutical excipients in drug formulations has recently garnered significant interest, as it has the potential to modify drug pharmacokinetics, leading to enhanced bioavailability [47], [48].
Ophthalmic formulations are most widely presented in the form of eye drops due to their simplicity of use and self-administration. Eye drops are liquid preparations to be instilled into the eye, containing at least one active ingredient and several other excipients responsible for modulating and enhancing characteristics such as tonicity, viscosity, pH, solubility of the drug, stability of the formulation, and its sterility [49]. The main roles of excipients in eye drops formulations are shown in Fig. 3.
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Materials
Table 1: Inactive ingredients currently approved for ocular human use. Adapted from the list “Inactive Ingredients in Approved Drug Products” in the FDA website.
Solubility enhancers
(vehicles, solvents, dissolution agents, suspending agents, drug delivery systems, surfactants)
Camphor (synthetic) | Solvent, co-solvent, penetration enhancer | 76,222 | Ophthalmic | Drops |
Castor oil | Vehicle, solubilizing agent, stabilizer | 8,001,794 | Ophthalmic | Emulsion |
Crospovidone | Water insoluble dissolution agent | 9,003,398 | Ophthalmic | Solution |
Dl-lactide and glycolide (50:50) copolymer 12,000 acid (PLGA) | Sustained release agent, bioadhesive, matrix former | 26,780,507 | Intravitreal | Implant |
Dl-lactide and glycolide (50:50) copolymer 12,000 acid (PLGA) | Sustained release agent, bioadhesive, matrix former | 26,780,507 | Intravitreal | Injection |
Ethylene-vinyl acetate copolymers (EVA) | Sustained release matrix, viscosity agent, film-forming agent | 24,937,788 | Ophthalmic | Insert, extended release |
Ethylene-vinyl acetate copolymers (EVA) | Sustained release matrix, viscosity agent, film-forming agent | 24,937,788 | Ophthalmic | Solution |
Glyceryl monostearate | Emulsifier, stabilizer, thickening agent | 91,052,470 | Ophthalmic | Suspension |
Guar gum | Controlled-release carrier | 9,000,300 | Ophthalmic | Suspension |
Hyaluronate sodium | Crosslinked gel as drug delivery systems | 9,067,327 | Intravitreal | Injection |
Hydrocarbon gel, plasticized | Gel base, viscosity agent, stabilizer | 8,049,658 | Ophthalmic | Ointment |
Hydroxypropyl.gamma.-cyclodextrin (γ-CD) | Solubilizing agent, drug delivery system, stabilizer | 128,446,344 | Ophthalmic | Solution |
Lanolin oil | Ointment base, emollient, stabilizer | 70,321,630 | Ophthalmic | Ointment |
Mannitol | Component of sustained-release tablet formulations | 69,658 | Ophthalmic | Suspension/ drops |
Menthol | Cooling agent, soothing effect, mild analgesic | Ophthalmic | Drops | |
Methylcellulose (MC) | Disintegrant; sustained-released preparations | 9,004,675 | Ophthalmic | Solution |
Methylcellulose (MC) | Disintegrant; sustained-released preparations | 9,004,675 | Ophthalmic | Solution/ drops |
Methylcellulose (MC) | Disintegrant; sustained-released preparations | 9,004,675 | Ophthalmic | Suspension |
Microcrystalline cellulose | Suspending vehicle (thixotropic gels) | 99,763 | Ophthalmic | Suspension/ drops |
Mineral oil | Solvent in o/w emulsions; used in microspheres | 9,004,346 | Intravitreal | Implant |
Mineral oil | Solvent in o/w emulsions; used in microspheres | 8,042,475 | Ophthalmic | Ointment |
Nonoxynol-9 | Surfactant, emulsifier, penetration enhancer | 7,778,770 | Ophthalmic | Suspension |
Octoxynol-40 | Surfactant | 9,002,931 | Ophthalmic | Solution |
Peanut oil | Vehicle, emollient, stabilizer | 9,002,931 | Ophthalmic | Solution/ drops |
Polyethylene glycol 300 (PEG) | Biodegradable polymeric matrices | 9,003,978 | Ophthalmic | Suspension/ drops |
Polyethylene glycol 400 (PEG) | Biodegradable polymeric matrices | 25,322,683 | Ophthalmic | Ointment |
Polyethylene glycol 400 (PEG) | Biodegradable polymeric matrices | 25,322,683 | Ophthalmic | Solution |
Polyethylene glycol 8000 (PEG) | Biodegradable polymeric matrices | 25,322,683 | Ophthalmic | Solution/ drops |
Polyoxyl 15 hydroxystearate | Solubilizing agent, emulsifying agent, stabilizer | 25,322,683 | Ophthalmic | Solution |
Polyoxyl 40 stearate | Solubilizing agent, emulsifying agent, stabilizer | 61,788,850 | Ophthalmic | Solution/ drops |
Polyoxyl 40 stearate | Solubilizing agent, emulsifying agent, stabilizer | Ophthalmic | Ointment | |
Polyoxyl 40 stearate | Solubilizing agent, emulsifying agent, stabilizer | Ophthalmic | Solution | |
Polypropylene glycol (PPG) | Solvent, thickening agent, lubricant, stabilizer | Ophthalmic | Suspension | |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,645 | Ophthalmic | Suspension |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,656 | Intravitreal | Injection, suspension |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,656 | Ophthalmic | Drops |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,656 | Ophthalmic | Emulsion |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,656 | Ophthalmic | Solution |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,656 | Ophthalmic | Solution, gel forming, extended release |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,656 | Ophthalmic | Solution/ drops |
Polysorbate 80 | Hydrophilic nonionic surfactant − o/w emulsions | 9,005,656 | Ophthalmic | Suspension |
Propylene glycol | Solvent, extractant and preservative/plasticizer/emulsifier | 9,003,398 | Ophthalmic | Suspension/ drops |
Propylene glycol | Solvent, extractant and preservative/plasticizer/emulsifier | 57,556 | Ophthalmic | Emulsion |
Propylene glycol | Solvent, extractant and preservative/plasticizer/emulsifier | 57,556 | Ophthalmic | Gel |
Propylene glycol | Solvent, extractant and preservative/plasticizer/emulsifier | 57,556 | Ophthalmic | Solution |
Propylene glycol | Solvent, extractant and preservative/plasticizer/emulsifier | 57,556 | Ophthalmic | Solution/ drops |
Propylene glycol | Solvent, extractant and preservative/plasticizer/emulsifier | 57,556 | Ophthalmic | Suspension |
Propylene glycol diacetate | Solvent, solubilizing agent, stabilizer | 57,556 | Ophthalmic | Suspension/ drops |
Sorbitol | Diluent/plasticizer | 50,704 | Ophthalmic | Solution |
Sorbitol solution | Diluent/plasticizer | 50,704 | Ophthalmic | Solution/ drops |
Sorbitol solution | Diluent/plasticizer | Ophthalmic | Drops | |
Titanium dioxide | Light-scattering properties/white pigment in film coating suspensions; opacifying agent | 54,648 | Ophthalmic | Suspension/ drops |
Tyloxapol | Nonionic surfactant | 25,301,024 | Ophthalmic | Gel |
Tyloxapol | Nonionic surfactant | 25,301,024 | Ophthalmic | Solution |
Tyloxapol | Nonionic surfactant | 25,301,024 | Ophthalmic | Solution/ drops |
Tyloxapol | Nonionic surfactant | 25,301,024 | Ophthalmic | Suspension |
Xanthan gum | Suspending agent/sustained release matrix | 8,009,038 | Ophthalmic | Ointment |
Xanthan gum | Suspending agent/sustained release matrix | 11,138,662 | Ophthalmic | Solution |
Xanthan gum | Suspending agent/sustained release matrix | 11,138,662 | Ophthalmic | Solution, gel forming, extended release |
Viscosity enhancers
(thickening agents, rheologic modifiers, lubricants, wetting agents, suspending vehicles, stabilizing agents)
Alginic acid | Thickening agent and emulsifier | 9,005,327 | Ophthalmic | Insert, extended release |
Carbomer copolymer type a (allyl pentaerythritol crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Emulsion | |
Carbomer copolymer type b (allyl pentaerythritol crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Emulsion | |
Carbomer homopolymer type b (allyl pentaerythritol crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Gel | |
Carbomer homopolymer type b (allyl pentaerythritol crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Suspension | |
Carbomer homopolymer type b (allyl pentaerythritol crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Suspension/ drops | |
Carbomer homopolymer type b (allyl sucrose crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Suspension | |
Carbomer homopolymer type b (allyl sucrose crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Suspension/ drops | |
Carbomer homopolymer type c (allyl pentaerythritol crosslinked) | Rheologic modifier (liquid or semisolid) | Ophthalmic | Gel | |
Carboxymethylcellulose sodium (CMC) | Suspending vehicle (thixotropic gels) | 9,004,324 | Intravitreal | Injection, suspension |
Carboxymethylcellulose sodium (CMC) | Suspending vehicle (thixotropic gels) | 9,004,324 | Ophthalmic | Solution |
Carboxymethylcellulose sodium (CMC) | Suspending vehicle (thixotropic gels) | 9,004,324 | Ophthalmic | Solution/ drops |
Dextran | Viscosity agent, stabilizer, lubricant | 9,004,540 | Ophthalmic | Solution/ drops |
Glycerin | Humectant, emollient; solvent/co-solvent | 56,815 | Ophthalmic | Emulsion |
Glycerin | Humectant, emollient; solvent/co-solvent | 56,815 | Ophthalmic | Gel |
Glycerin | Humectant, emollient; solvent/co-solvent | 56,815 | Ophthalmic | Solution |
Glycerin | Humectant, emollient; solvent/co-solvent | 56,815 | Ophthalmic | Solution/ drops |
Glycerin | Humectant, emollient; solvent/co-solvent | 56,815 | Ophthalmic | Suspension |
Glycerin | Humectant, emollient; solvent/co-solvent | 56,815 | Ophthalmic | Suspension/ drops |
Hydroxyethyl cellulose (4000 mpa.s at 1%) (HEC) | Thickening agent | 9,004,620 | Ophthalmic | Solution/ drops |
Hydroxyethyl cellulose (5000 mpa.s at 1%) (HEC) | Thickening agent | 9,004,620 | Ophthalmic | Solution |
Hydroxyethyl ethylcellulose (HEEC) | Thickening agent, film-forming, suspending agent | 9,004,584 | Ophthalmic | Solution/ drops |
Hypromellose (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Solution/ drops |
Hypromellose (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Suspension |
Hypromellose (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Suspension/ drops |
Hypromellose 2906 (4000 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Solution |
Hypromellose 2910 (3 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Solution/ drops |
Hypromellose 2910 (4000 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Drops |
Hypromellose 2910 (4000 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Gel |
Hypromellose 2910 (4000 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Solution |
Hypromellose 2910 (4000 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Solution/ drops |
Hypromellose 2910 (4000 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Suspension |
Hypromellose 2910 (4000 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Suspension/ drops |
Hypromellose 2910 (5 mpa.s) (HPMC) | Thickening agent (eye drops) | 9,004,653 | Ophthalmic | Solution |
Magnesium stearate | Lubrificant | 557,040 | Intravitreal | Implant |
Magnesium stearate | Lubrificant | 557,040 | Intravitreal | System |
Poloxamer 188 | Wetting agents/DDS | 75,345,276 | Ophthalmic | Solution |
Poloxamer 407 | Wetting agents/DDS | 691,397,134 | Ophthalmic | Solution |
Poloxamer 407 | Wetting agents/DDS | 691,397,134 | Ophthalmic | Gel |
Poloxamer 407 | Wetting agents/DDS | 691,397,134 | Ophthalmic | Solution |
White petrolatum | Emollient, protective agent, ointment base | 25,301,024 | Ophthalmic | Suspension/ drops |
Polyvinyl alcohol (PVA) | Stabilizing agent for emulsions/viscosity-increasing agent | 9,002,895 | Ophthalmic | Suspension |
Povidone (PVP) | Suspending, stabilizing or viscosity-increasing agent | 24,634,615 | Ophthalmic | Solution/ drops |
Povidone (PVP) | Suspending, stabilizing or viscosity-increasing agent | 9,003,398 | Ophthalmic | Solution |
Povidone (PVP) | Suspending, stabilizing or viscosity-increasing agent | 9,003,398 | Ophthalmic | Suspension |
Povidone k30 (PVP) | Mm= 50,000 occurs as spheres | 9,003,398 | Ophthalmic | Suspension/ drops |
Povidone k30 (PVP) | Mm= 50,000 occurs as spheres | 9,003,398 | Ophthalmic | Solution |
Povidone k30 (PVP) | Mm= 50,000 occurs as spheres | 9,003,398 | Ophthalmic | Solution/ drops |
Povidone k90 (PVP) | Mm= 1,000,000 | 9,003,398 | Ophthalmic | Suspension |
Povidone k90 (PVP) | Mm= 1,000,001 | 9,003,398 | Ophthalmic | Solution |
Povidone k90 (PVP) | Mm= 1,000,002 | 9,003,398 | Ophthalmic | Solution/ drops |
Sodium polystyrene sulfonate | Thickening agent, stabilizing agent, cation exchange resin | 10,049,215 | Ophthalmic | Suspension |
Sodium polystyrene sulfonate | Thickening agent, stabilizing agent, cation exchange resin | 25,704,181 | Ophthalmic | Suspension |
White petrolatum | Emollient, protective agent, ointment base | 25,301,024 | Ophthalmic | Suspension/ drops |
Penetration enhancers
(chelating agents, emollients)
Cetyl alcohol | Emollient agent/water absorption properties | 36,653,824 | Ophthalmic | Suspension |
Edetate disodium (EDTA) | Chelating agent | 6,381,926 | Ophthalmic | Drops |
Edetate disodium (EDTA) | Chelating agent | 6,381,926 | Ophthalmic | Emulsion |
Edetate disodium (EDTA) | Chelating agent | 6,381,926 | Ophthalmic | Gel |
Edetate disodium (EDTA) | Chelating agent | 6,381,926 | Ophthalmic | Solution |
Edetate disodium (EDTA) | Chelating agent | 6,381,926 | Ophthalmic | Solution/ drops |
Edetate disodium (EDTA) | Chelating agent | 6,381,926 | Ophthalmic | Suspension |
Edetate disodium (EDTA) | Chelating agent | 6,381,926 | Ophthalmic | Suspension/ drops |
Edetate sodium (EDTA) | Chelating agent | 64,028 | Ophthalmic | Emulsion |
Edetate sodium (EDTA) | Chelating agent | 64,028 | Ophthalmic | Solution |
Petrolatum | Emollient-ointment base/lubricant | Ophthalmic | Solution |
Buffering agents
|
||||
---|---|---|---|---|
Acetic acid | Acidifying agent/buffer | 64,197 | Ophthalmic | Solution |
Acetic acid | Acidifying agent/buffer | 64,197 | Ophthalmic | Solution/ drops |
Ammonia solution | Buffering agent | 7,664,417 | Ophthalmic | Solution |
Anhydrous citric acid | Buffering agent | 77,929 | Ophthalmic | Solution |
Anhydrous citric acid | Buffering agent | 77,929 | Ophthalmic | Suspension/ drops |
Citric acid monohydrate | Buffering agent | 5,949,291 | Intraocular | Injection, solution, concentrate |
Citric acid monohydrate | Buffering agent | 5,949,291 | Intraocular | Solution |
Citric acid monohydrate | Buffering agent | 5,949,291 | Ophthalmic | Solution |
Citric acid monohydrate | Buffering agent | 5,949,291 | Ophthalmic | Solution/ drops |
Citric acid monohydrate | Buffering agent | 5,949,291 | Ophthalmic | Suspension |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Intraocular | Injection, solution, concentrate |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Intraocular | Solution |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Intravitreal | Injection |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Intravitreal | Injection, suspension |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Ophthalmic | Emulsion |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Ophthalmic | Gel |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Ophthalmic | Solution |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Ophthalmic | Solution/ drops |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Ophthalmic | Suspension |
Hydrochloric acid | Acidifying agent/buffer | 7,647,010 | Ophthalmic | Suspension/ drops |
Magnesium chloride | Buffering agent, osmotic agent | 7,791,186 | Intraocular | Solution |
Magnesium chloride | Buffering agent, osmotic agent | 7,791,186 | Intravitreal | Injection, suspension |
Magnesium chloride | Buffering agent, osmotic agent | 7,791,186 | Ophthalmic | Solution |
Magnesium chloride | Buffering agent, osmotic agent | 7,791,186 | Ophthalmic | Solution/ drops |
Monobasic potassium phosphate | Buffering agent, tonicity adjuster, stabilizer | 8,042,475 | Ophthalmic | Suspension |
Monobasic potassium phosphate | Buffering agent, tonicity adjuster, stabilizer | 7,778,770 | Ophthalmic | Solution |
Sodium acetate | Forms a buffer system when combined with acetic acid | 6,131,904 | Intraocular | Solution |
Sodium acetate | Forms a buffer system when combined with acetic acid | 6,131,904 | Intravitreal | Injection, suspension |
Sodium acetate | Forms a buffer system when combined with acetic acid | 6,131,904 | Ophthalmic | Emulsion |
Sodium acetate | Forms a buffer system when combined with acetic acid | 6,131,904 | Ophthalmic | Solution |
Sodium acetate anhydrous | Buffering agent | 6,131,904 | Ophthalmic | Solution/ drops |
Sodium borate | Similar usage to boric acid/adstringent and emulsifying | 7,631,905 | Ophthalmic | Suspension |
Sodium borate | Similar usage to boric acid/adstringent and emulsifying | 1,303,964 | Ophthalmic | Emulsion |
Sodium borate | Similar usage to boric acid/adstringent and emulsifying | 1,303,964 | Ophthalmic | Solution |
Sodium borate | Similar usage to boric acid/adstringent and emulsifying | 1,303,964 | Ophthalmic | Solution/ drops |
Sodium carbonate | Alkalizing agent | 1,303,964 | Ophthalmic | Suspension/ drops |
Sodium carbonate monohydrate | Alkalizing agent | 497,198 | Ophthalmic | Solution |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 5,968,116 | Ophthalmic | Solution |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Intraocular | Injection, solution, concentrate |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Intraocular | Solution |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Intravitreal | Injection |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Intravitreal | Injection, suspension |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Ophthalmic | Drops |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Ophthalmic | Gel |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Ophthalmic | Powder, for solution |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Ophthalmic | Solution |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Ophthalmic | Solution/ drops |
Sodium chloride | Used to produce isotonic solutions/modifies drug release from gels and emulsions | 7,647,145 | Ophthalmic | Suspension |
Sodium hydroxide | Used to adjust the ph | 7,647,145 | Ophthalmic | Suspension/ drops |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Intraocular | Solution |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Intravitreal | Injection |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Intravitreal | Injection, suspension |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Ophthalmic | Drops |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Ophthalmic | Emulsion |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Ophthalmic | Gel |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Ophthalmic | Solution |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Ophthalmic | Solution/ drops |
Sodium hydroxide | Used to adjust the ph | 1,310,732 | Ophthalmic | Suspension |
Sodium phosphate | Buffering agent, electrolyte source | 7,631,994 | Ophthalmic | Solution |
Sodium phosphate | Buffering agent, electrolyte source | 7,632,055 | Ophthalmic | Solution |
Sodium phosphate | Buffering agent, electrolyte source | 7,632,055 | Ophthalmic | Solution/ drops |
Sodium phosphate, dibasic, anhydrous | Buffering agent and sequestering agent | 10,140,655 | Ophthalmic | Suspension |
Sodium phosphate, dibasic, anhydrous | Buffering agent and sequestering agent | 7,558,794 | Intraocular | Insert |
Sodium phosphate, dibasic, anhydrous | Buffering agent and sequestering agent | 7,558,794 | Ophthalmic | Solution |
Sodium phosphate, dibasic, anhydrous | Buffering agent and sequestering agent | 7,558,794 | Ophthalmic | Solution/ drops |
Sodium phosphate, dibasic, dihydrate | Buffering agent and sequestering agent | 7,558,794 | Ophthalmic | Suspension |
Sodium phosphate, dibasic, dodecahydrate | Buffering agent and sequestering agent | 10,028,247 | Ophthalmic | Solution/ drops |
Sodium phosphate, dibasic, dodecahydrate | Buffering agent and sequestering agent | 10,039,324 | Ophthalmic | Solution |
Sodium phosphate, dibasic, heptahydrate | Buffering agent and sequestering agent | 10,039,324 | Ophthalmic | Solution/ drops |
Sodium phosphate, dibasic, heptahydrate | Buffering agent and sequestering agent | 7,782,856 | Intravitreal | Injection |
Sodium phosphate, dibasic, heptahydrate | Buffering agent and sequestering agent | 7,782,856 | Ophthalmic | Solution |
Sodium phosphate, dibasic, heptahydrate | Buffering agent and sequestering agent | 7,782,856 | Ophthalmic | Solution/ drops |
Sodium phosphate, dibasic, heptahydrate | Buffering agent and sequestering agent | 7,782,856 | Ophthalmic | Suspension |
Sodium phosphate, monobasic | Buffering agent and sequestering agent | 7,782,856 | Ophthalmic | Suspension/ drops |
Sodium phosphate, monobasic | Buffering agent and sequestering agent | − | Ophthalmic | Solution |
Sodium phosphate, monobasic, anhydrous | Buffering agent and sequestering agent | − | Ophthalmic | Solution/ drops |
Sodium phosphate, monobasic, anhydrous | Buffering agent and sequestering agent | 7,558,807 | Intraocular | Insert |
Sodium phosphate, monobasic, anhydrous | Buffering agent and sequestering agent | 7,558,807 | Ophthalmic | Solution |
Sodium phosphate, monobasic, anhydrous | Buffering agent and sequestering agent | 7,558,807 | Ophthalmic | Solution/ drops |
Sodium phosphate, monobasic, anhydrous | Buffering agent and sequestering agent | 7,558,807 | Ophthalmic | Suspension |
Sodium phosphate, monobasic, dihydrate | Buffering agent and sequestering agent | 7,558,807 | Ophthalmic | Suspension/ drops |
Sodium phosphate, monobasic, dihydrate | Buffering agent and sequestering agent | 13,472,350 | Ophthalmic | Solution |
Sodium phosphate, monobasic, monohydrate | Buffering agent and sequestering agent | 13,472,350 | Ophthalmic | Solution/ drops |
Sodium phosphate, monobasic, monohydrate | Buffering agent and sequestering agent | 10,049,215 | Intravitreal | Injection |
Sodium phosphate, monobasic, monohydrate | Buffering agent and sequestering agent | 10,049,215 | Ophthalmic | Solution |
Sodium phosphate, monobasic, monohydrate | Buffering agent and sequestering agent | 10,049,215 | Ophthalmic | Solution/ drops |
Sodium sulfate | Buffering agent, tonicity adjuster | 25,704,181 | Ophthalmic | Suspension/ drops |
Sodium sulfate | Buffering agent, tonicity adjuster | 7,727,733 | Ophthalmic | Solution |
Sodium sulfate | Buffering agent, tonicity adjuster | 7,727,733 | Ophthalmic | Solution/ drops |
Sodium sulfate anhydrous | Tonicity adjuster, stabilizer | 7,727,733 | Ophthalmic | Suspension |
Sodium sulfate anhydrous | Tonicity adjuster, stabilizer | 7,757,826 | Ophthalmic | Solution |
Sodium sulfate anhydrous | Tonicity adjuster, stabilizer | 7,757,826 | Ophthalmic | Solution/ drops |
Trisodium citrate dihydrate | Buffering agent, chelating agent | 13,463,677 | Ophthalmic | Insert, extended release |
Trisodium citrate dihydrate | Buffering agent, chelating agent | 6,132,043 | Intraocular | Injection, solution, concentrate |
Trisodium citrate dihydrate | Buffering agent, chelating agent | 6,132,043 | Intraocular | Solution |
Trisodium citrate dihydrate | Buffering agent, chelating agent | 6,132,043 | Intravitreal | Injection, suspension |
Trisodium citrate dihydrate | Buffering agent, chelating agent | 6,132,043 | Ophthalmic | Solution |
Trisodium citrate dihydrate | Buffering agent, chelating agent | 6,132,043 | Ophthalmic | Solution/drops |
Preservatives (antimicrobial and antioxidant agents) |
||||
---|---|---|---|---|
Alcohol | Solvent/antimicrobial preservative | 64,175 | Ophthalmic | Solution |
Benzalkonium chloride | Antimicrobial preservative | 8,001,545 | Ophthalmic | Drops |
Benzalkonium chloride | Antimicrobial preservative | 8,001,545 | Ophthalmic | Gel |
Benzalkonium chloride | Antimicrobial preservative | 8,001,545 | Ophthalmic | Solution |
Benzalkonium chloride | Antimicrobial preservative | 8,001,545 | Ophthalmic | Solution/ drops |
Benzalkonium chloride | Antimicrobial preservative | 8,001,545 | Ophthalmic | Suspension |
Benzalkonium chloride | Antimicrobial preservative | 8,001,545 | Ophthalmic | Suspension/ drops |
Benzethonium chloride | Antimicrobial preservative | 121,540 | Ophthalmic | Solution/ drops |
Benzododecinium bromide | Antimicrobial preservative | 7,281,041 | Ophthalmic | Solution, gel forming, extended release |
Boric acid | Antimicrobial preservative/buffering agent | 10,043,353 | Ophthalmic | Emulsion |
Boric acid | Antimicrobial preservative/buffering agent | 10,043,353 | Ophthalmic | Gel |
Boric acid | Antimicrobial preservative/buffering agent | 10,043,353 | Ophthalmic | Solution |
Boric acid | Antimicrobial preservative/buffering agent | 10,043,353 | Ophthalmic | Solution, gel forming, extended release |
Boric acid | Antimicrobial preservative/buffering agent | 10,043,353 | Ophthalmic | Solution/ drops |
Boric acid | Antimicrobial preservative/buffering agent | 10,043,353 | Ophthalmic | Suspension |
Boric acid | Antimicrobial preservative/buffering agent | 10,043,353 | Ophthalmic | Suspension/ drops |
Butylparaben | Antimicrobial preservative | 94,268 | Ophthalmic | Solution |
Calcium chloride | Antimicrobial preservative/desiccant | 10,035,048 | Intraocular | Solution |
Calcium chloride | Antimicrobial preservative/desiccant | 10,035,048 | Intravitreal | Injection, suspension |
Calcium chloride | Antimicrobial preservative/desiccant | 10,035,048 | Ophthalmic | Solution |
Calcium chloride | Antimicrobial preservative/desiccant | 10,035,048 | Ophthalmic | Solution/ drops |
Cetylpyridinium chloride | Antimicrobial preservative | 6,004,246 | Ophthalmic | Solution |
Chlorobutanol | Antimicrobial preservative | 57,158 | Ophthalmic | Drops |
Chlorobutanol | Antimicrobial preservative | 57,158 | Ophthalmic | Ointment |
Chlorobutanol | Antimicrobial preservative | 57,158 | Ophthalmic | Solution |
Eucalyptol | Antiseptic, solvent, penetration enhancer | 470,826 | Ophthalmic | Drops |
Methylparaben | Antimicrobial preservative | 99,763 | Ophthalmic | Ointment |
Methylparaben | Antimicrobial preservative | 99,763 | Ophthalmic | Solution |
Methylparaben | Antimicrobial preservative | 99,763 | Ophthalmic | Solution/ drops |
Phenol | Antimicrobial preservative | 8,009,038 | Ophthalmic | Ointment |
Phenylethyl alcohol | Antimicrobial preservative | 108,952 | Ophthalmic | Drops |
Phenylmercuric acetate | Antimicrobial preservative/better solubility | 60,128 | Ophthalmic | Solution |
Phenylmercuric acetate | Antimicrobial preservative/better solubility | 62,384 | Ophthalmic | Ointment |
Phenylmercuric nitrate | Antimicrobial preservative | 62,384 | Ophthalmic | Solution |
Phenylmercuric nitrate | Antimicrobial preservative | 55,685 | Ophthalmic | Ointment |
Phosphoric acid | Acidifying agent/buffer | 55,685 | Ophthalmic | Solution |
Polidronium chloride | Antimicrobial preservative | 7,664,382 | Ophthalmic | Solution |
Potassium sorbate | Antimicrobial preservative (enhances ocular bioavailability of timolol) | 24,634,615 | Ophthalmic | Emulsion |
Propylparaben | Antimicrobial preservative | 623,847 | Ophthalmic | Solution/ drops |
Propylparaben | Antimicrobial preservative | 94,133 | Ophthalmic | Drops |
Propylparaben | Antimicrobial preservative | 94,133 | Ophthalmic | Ointment |
Propylparaben | Antimicrobial preservative | 94,133 | Ophthalmic | Solution |
Propylparaben | Antimicrobial preservative | 94,133 | Ophthalmic | Solution/ drops |
Sodium bisulfite | Preservative, antioxidant, pH adjuster | 144,558 | Intravitreal | Injection |
Sodium bisulfite | Preservative, antioxidant, pH adjuster | 7,631,905 | Ophthalmic | Drops |
Sodium bisulfite | Preservative, antioxidant, pH adjuster | 7,631,905 | Ophthalmic | Solution |
Sodium bisulfite | Preservative, antioxidant, pH adjuster | 7,631,905 | Ophthalmic | Solution/ drops |
Sodium nitrate | Buffering agent | 7,681,574 | Ophthalmic | Suspension/ drops |
Sodium thiosulfate | Antioxidant/antimicrobial (fungi) | 10,102,177 | Ophthalmic | Solution |
Sodium thiosulfate | Antioxidant/antimicrobial (fungi) | 10,102,177 | Ophthalmic | Solution/ drops |
Sodium thiosulfate | Antioxidant/antimicrobial (fungi) | 10,102,177 | Ophthalmic | Suspension |
Sorbic acid | Antimicrobial preservative | 10,102,177 | Ophthalmic | Suspension/ drops |
Sorbic acid | Antimicrobial preservative | 110,441 | Ophthalmic | Emulsion |
Sorbic acid | Antimicrobial preservative | 110,441 | Ophthalmic | Solution |
Thimerosal | Antimicrobial preservative (bacteriostatic and fungistatic) | 7,664,939 | Ophthalmic | Suspension |
Thimerosal | Antimicrobial preservative (bacteriostatic and fungistatic) | 54,648 | Ophthalmic | Solution |
Thimerosal | Antimicrobial preservative (bacteriostatic and fungistatic) | 54,648 | Ophthalmic | Solution/ drops |
Thimerosal | Antimicrobial preservative (bacteriostatic and fungistatic) | 54,648 | Ophthalmic | Suspension |
Zinc chloride | Antimicrobial preservative, astringent | 11,138,662 | Ophthalmic | Suspension |
Zinc chloride | Antimicrobial preservative, astringent | 7,646,857 | Ophthalmic | Solution |
See a broad list of Inactive ingredients currently approved for ocular human use.
Excipients mentioned in the article beside others: crospovidone, cyclodextrin, mannitol, methylcellulose, polysorbates, MCC, PEG, Propylene glycol, sorbitol, titanium dioxide, xanthan gum, carbomer, HPMC, poloxamer, povidone
Raquel Arribada, Daniela Rodrigues-Braz, Armando Silva-Cunha, Francine Behar-Cohen, Excipients in drug delivery systems: A comprehensive review of approved inactive ingredients for human ophthalmic formulations, European Journal of Pharmaceutics and Biopharmaceutics, 2025, 114637, ISSN 0939-6411, https://doi.org/10.1016/j.ejpb.2025.114637.