Hot Melt Extrusion Technology in Taste Masking

Abstract

Hot melt extrusion (HME) is a widely used method of taste masking in medication formulations, notably for bitter Active Pharmaceutical Ingredients (APIs). This continuous, solvent-free technique successfully wraps APIs within a polymer matrix, forming a barrier that considerably decreases bitterness perception. These advantageous properties of HME in taste masking are especially important for pediatric, geriatric, and veterinary formulations, where palatability is critical. The technique entails melting a polymer matrix and combining it with the medicine, followed by extrusion to make granules or dosage forms. The efficacy of taste masking is dependent on selecting acceptable excipients and ensuring their compatibility with the medicine. Temperature, screw speed, and drug-to-polymer ratio are critical process parameters that must be tuned. Various screw configurations can influence the physical condition of the API during extrusion, increasing taste-masking efficacy. Future advances in HME technology are expected, with a focus on enhancing taste masking for a broader range of APIs. Innovations in the study of polymers and the combination of process analytical technology (PAT) will significantly enhance the effectiveness and reliability of flavor-masked formulations, resolving the important need for patient-friendly drugs that are taken orally.

Introduction

Drug delivery through the oral route is the simplest and most widely used method across all age ranges. Oral dosages are used due to their convenience of administration, non-invasiveness, and do not require specialized training, unlike the parenteral route, and enhance patient compliance. Patient compliance is heavily influenced by the perceived taste or palatability of pharmaceutical dosage forms [1,2,3,4]. Developing taste-masked formulations for oral dosage forms poses a significant challenge, especially for the elderly, children, and animal populations with distinct taste preferences. The majority of APIs have a bitter taste, which is a major challenge in developing palatable oral medications [5,6,7,8]. Pharmacologically blocking taste receptors is difficult and unpleasant due to the numerous bitter receptors present on the tongue. The mechanism of action of API at the molecular level makes it a difficult task to eliminate the molecular entities that create a bitter taste from the formulation. Pharmaceutical companies dedicate time and resources to developing palatable and pleasing-tasting products. They also use taste-masking procedures to generate appropriate taste-masked oral dosage forms. Currently, there are several taste-masking technologies available. Microencapsulation, freeze-drying, high shear mixing, fluidized bed coating, supercritical fluids, and spray drying have all been asserted as effective methods for disguising the taste of diverse bitter active compounds [6, 8, 9]. An affordable flavor-masking method is necessary to prevent the API from coming into direct touch with the taste buds present in the mouth.

One emerging and promising approach for taste masking is hot-melt extrusion (HME) technology, which involves developing solid dispersions where in drug is embedded in a carrier medium for the development of pharmaceutical dosage forms. It is a cost-effective, solvent-free,’green’technique that is used for multiple formulations with reduced investment costs compared to traditional technologies [10,11,12,13,14]. The solvent-free nature of HME technology makes it an appealing choice for simple scaling up, which substantially lowers potential safety concerns and environmental impact when compared to solvent-based methods [8, 15,16,17,18,19,20,21,22]. It is a continuous process, making it incredibly inexpensive and efficient for pharma product manufacture. It often involves fewer stages of processing than other techniques, such as spray drying [15, 16] It facilitates for the customization of formulations and dosage forms by varying parameters such as drug-to-polymer ratio, screw arrangement, and processing conditions. It is also a mature, robust technology that can easily grow to meet customer demands [1, 2, 4, 23,24,25].

HME converts poorly water-soluble active pharmaceutical ingredients into an amorphous solid dispersion, which improves their solubility and dissolution significantly by breaking the drug’s crystal lattice, resulting in increased bioavailability [1, 15, 16, 26]. HME can be utilized for the production of tablets [which include immediate release, sustained release, and orally disintegrating tablets (ODTs)], capsules, granules (effervescent granules and granules for immediate release formulation), films, pellets, implants, and patches [4, 11, 27,28,29]. The various solutions provided by HME are illustrated in Fig. 1.

The process by which HME masks the taste includes melting the drug and carrier polymer together at a high temperature, along with mixing them and extruding the molten mass through the die to produce a solid dispersion. Various bitter API whose taste is masked using HME technology are discussed in Table I. Frequently used polymers in masking the taste include Eudragit^® E PO, Eudragit^® RL PO, Kollicoat® Smartseal 30 D, Eudragit^® E100,  Kollidon^® VA 64 and Soluplus® [30,31,32,33]. These polymers limit the release of the bitter medicine in the saliva by producing a coating around the API, so as to avoid interaction with taste receptors on the tongue. Several researchers have used both in vitro and in vivo methodologies to assess HME’s taste masking efficacy. Taste sensor technologies, such as electronic tongues, have been utilized to compare in vitro data to in vivo taste ratings by human panels. These experiments have established the efficiency of HME in enhancing the taste of bitter APIs. The strongest masking effect was obtained for certain polymer-API combinations at specified drug loadings.

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Table I Bitter Drugs Which Have Been Successfully Taste-masked Using HME Technology

Following excipients are mentioned in the study besides other: polyvinyl caprolactam (Soluplus®), polyethylene glycol (PEG), citric acid, glycerol, triethyl citrate, polyvinylpyrrolidone (PVP), stearic acid, and glyceryl behenate

Nayak, G., Nayak, U.Y. Hot Melt Extrusion Technology in Taste Masking. AAPS PharmSciTech 26, 196 (2025). https://doi.org/10.1208/s12249-025-03174-9