Surface Solid Dispersion Review

Oral route is mostly preferred route for administering drugs to patient. But due to the poor solubility many drug has limited used in oral administration. Enhancement of water solubility of poor water soluble drug is a main target in a pharmaceutical field. Surface solid dispersion is aneffective method to enhance the solubility of poorly water soluble drugs, however due to ease of method of formation of surface solid dispersion,it is a novel method that is cost effective, in which surface area for absorption of drug can increased which increases dissolution of drug. The review article focuses on the methods of preparation, advantages, disadvantages and characterization of the surface solid dispersions.

I. Introduction

The substance ability to dissolve in a specific solvent is known as solubility. It is a measure of the concentration of dissolved solute in a saturated solution at a particular temperature. In terms of quality, it denotes the spontaneous interaction of two or more components to produce a single, distinct phase homogenous dispersion of molecules [1]. Since the dissolution rate is the mechanism that limits the rate with which a drug is absorbed from a solid dosage form, the pharmaceutical industry has long struggled with the poor solubility characteristics of relatively insoluble compounds. While summarizing the physicochemical elements influencing the dissolution rate in this instance, the Noyes-Whitney and formulas for Nernst. Surface area directly affects the dissolution rate, which can be raised by aiming to reduce the drug’s particle size[2]. Numerous methods, involving salt formation, turning drugs into prodrugs, and micronization, were used to increase the solubility of poorly soluble drugs besides this, complexation, micelle formation, and nanonization emulsions, solid-lipid nanoparticles, and solid-liquid dispersions. A typical way to improve a drug’s aqueous solubility is solid dispersion, in which one more active ingredient(s) is distributed evenly in a water-soluble inert carrier matrix[1]. Drug amorphization promotes wettability which is the principal mechanism in which there is decrease in particle size which can greatly facilitate disintegration. Despite the fact that solid dispersions have a range of benefits, the water soluble carriers employed in their production result in a soft, sticky mass that is challenging to handle. Particularly in tablet compression [3].Another method for dispersion of one or more active substances on a water-insoluble-hydrophilic carrier of exceptionally large surface area to achieve increased dissolution rates and bioavailability of insoluble drugs is Surface Solid Dispersion (SSD). SSD uses carrier which spreads when it comes into touch with water, enabling the drug’s quick release right away. [5]. Moreover, at high concentrations of such carriers might reduce solvation due to the high viscosity surface boundary [4]. Surface solid dispersion technology is likely to significantly increase the solubility and bioavailability of poorly water soluble drugs. This when combined with product development, technique Orodispersible tablets are anticipated to improve the drug’s ability to dissolve [6].

Carrier selection
1st Generation: Crystalline carriers; Urea, sugar and organic acid
2nd Generation: Amorphous carriers; PEG, PVA, Povidone and Cellulose derivatives
3rd Generation: Surface active self-emulsifying carriers; Poloxamer 407, tween 80, Gelucire 44/14, compritol 888 ATO +/- polymer

Ideal properties of a carrier for surface solid dispersions
1. High water solubility, promotes wettability and increases dissolution
2. High glass transition point (Tg) and improve stability
3. Minimal water uptake (reduces Tg)
4. Soluble in common solvent with drug (solvent evaporation technique)
5. Relatively low melting point (melting process)
6. Capable of forming a solid solution with the drug
7. Good compressibility index and flow index
8. Ability to protect drug from moisture

Examples of different polymers used in surface solid dispersions:

drug	polymer	method of preparation	Results observed	reference
Ebastine	Croscarmellosesodium, Avicel®pH101, Avicel®pH102, SodiumStarch Glycolate (SSG)	Solvent Evaporation Method	(EBS: CCS 1:15) showed high percentage yield (98.5%), high drug content (98.39%) and 8.2 fold increase in solubility compared to solubility of pure drug with improved dissolution rate	1
Felodipine	Porous Silicon Dioxide kg 100, Sodium Chloride	Physical Mixture, Solvent Deposition	the dissolution rate of felodipine from solvent deposit as well as vacuumprepared surface solid dispersions increased markedly as compared to the dissolution rate of felodipine alone, and also increased in comparison to the dissolution rate of ambienttemperature-prep & physical mixture	2
Meloxicam	Crospovidone	Co-grinding and Solvent Evaporation Method	Tablet formulation F3 made with SSD3 with a disintegration time of 11 secs, by wetting time= 6 sec, high water absorption of 78% by wt and cumulative drug release of 97% proved to be superior than the tablet made with SD3	3
Nifedipine	Sodium Starch Glycolate (SSG) and Croscarmellose sodium (CCS)	Co-precipitation technique	Tablets prepared from SD of nifedipine with Poloxamer and PEG 6000 were found to have better drug release profile than the marketed products.	4
Glimepiride	Crospovidone, Pregelatinised Starch, Croscarmellose Sodium and Avicel pH 101	Solvent Evaporation Method.	The surface solid dispersion on crospovidone with drug to carrier ratio of 1:19 showed highest dissolution rate with the dissolution efficiency of 81.89% in comparison to pure drug (22.88%) and physical mixture (35.96%	7
Clopidogrelb isulfate	PEG 4000, PEG 6000, Poloxomer 188	Solvent Evaporation and Hot melt Method.	The Clopidogrelbisulfate containing an optimized formulation of surface solid dispersion showed 85.69% drug release in 30 min.	13
Piroxicam	Microcrystalline Cellulose (Avicel pH101) and Potato Starch	Coevaporation Method.	The dissolution rate of the drug in potato starch based surface solid dispersion was significantly higher than that in the microcrystalline cellulose based SSD.	14
Irbesartan	Crospovidone (CP), Sodium Starch Glycolate (SSG), Potato Starch (PS), Croscarmellose (CC), Microcrystalline Cellulose (MC)	Solvent Coevaporation Method	The in vitro dissolution studies of surface solid dispersion of crospovidone with drug to carrier ratio of 1:10 showed highest dissolution rate with the dissolution efficiency of 98.18% (10 min)	15
Meclizine hydrochloride	Gelucire 50/13 and Gelucire 44/14, Polyethylene Glycol 8000	Melt Method	The presence of Gelucire 44/14 in the formulation showed significant enhancement in solubility (152 folds) and dissolution rate (7.23 folds).	16
Telmisartan	Avicel pH101,Alginic Acid, Aerosil 200, PEG 4000, PEG 6000, poloxamer 407, Poloxamer 188,	Solvent Evaporation Method	The hydrophilic polymers, such as Avicel PH101, Alginic acid, and Aerosil200 were found to be effective in increasing the aqueous solubility and dissolution rate of Telmisartan in surface solid dispersions when compared to the pure drug	17,18
Ketoprofen	Aerosil 200	Solvent Evaporation Method	Surface adsorption on inert carriers such as aerosil 200 was very successful tool for enhancement the dissolution rate of ketoprofen.	19
Simvastatin	1. polyethylene glycol 6000, Pluronic f68, Myrj 52 and Polyvinyl PyrrolidoneK-30 2. Sodium Starch Glycolate (SSG) and Croscarmellose sodium (CCS)	Solvent Deposition Technique, Coevaporation and Cogrinding	1. PVP K-30 showing better dissolution parameters that was comparable to that of marketed product. 2. Bioavailability is improved due to enhancement in rate and extent of drug release when drug was administered as an SSD using CCS as a carrier.	6,20
Carvedilol	Avicel pH 101, Pluronic f68	Solvent Evaporation Method	Water insoluble, hydrophilic carrier accompanied by Pluronic F68, as a wetting agent, largely improved drug dissolution that was comparable to the marketed product of CRV	21
Olmesartan Medoxomil	Avicel pH 102,Ac-diSol,Kyron t-314, crospovidone, Lycatab, Starlac,	Solvent evaporation method	SSD18 consisting of drug: SSG at 1:9 ratio and SSD20 consisting of drug:Kyron T-314 at 1:5 ratio showed the highest enhancement in the dissolution rate and efficiency of olmesartan medoxomil compared to the plain drug and the physical mixtures.	22

Download the full review as PDF here: Surface Solid Dispersion Review

Miss.Namrata Nitin Haladkar, Miss Rajshree A. Kabade,Prof.Y.N.Gavhane, Surface Solid Dispersion Review, International Journal of Pharmaceutical Research and Applications
Volume 8, Issue 2 Mar-Apr 2023, ISSN: 2249-7781,
DOI: 10.35629/7781-0802720729