Structural and in vitro in vivo evaluation for taste masking

ABSTRACT

Introduction: Although many techniques, such as complexation and microencapsulation, are used to mask the unpleasant taste of drugs, the success of all masking processes is evaluated in the same way. To evaluate the success of a masking process, a masked formulation must pass two tests: a structural test and an in vitro in vivo test.

Areas covered: This review article highlights structural evaluation and in vitro in vivo evaluation of a taste-masking process. The structural evaluation has two criteria: the absence of any chemical interaction between the drug and the masking agent and the molecular distribution of drug in the network of masking agent. The in vitro in vivo section can be verified by electronic tongues, dissolution test, and volunteers and it should confirm that the final product, after applying the masking process, will have a lower rank in terms of taste.

Expert opinion: This critical review helps researchers and industrial partners to evaluate a taste-masking process in a systematic way, leading to better understanding of taste-masking process and consequently improving the efficiency of masked dosage forms while hindering the unpleasant taste of drugs. This will ultimately improve the quality of life of many patients.

KEYWORDS:

• Taste masking
• solid dispersion
• dissolution test
• in vivo in vitro evaluation and e-tongues

Article highlights

• Although many methods can be used in taste masking, solid dispersion, where an active pharmaceutical ingredient with unpleasant taste is distributed within the network of a masking agent, is the most common method.

• Taste-masking evaluation process can be divided into two main parts: a structural evaluation and an in vitro in vivo evaluation.

• The first part of taste-masking evaluation process is the structural evaluation. This evaluation can be carried out by many analytical techniques such as FT-IR, DSC, and PXRD to ensure that the final masked product is a solid dispersion of API in masking agent. FT-IR ensures that no chemical interaction has occurred between API and masking agent while DSC and PXRD ensure that API has distributed homogenously within the network of masking agent.

• The in vitro in vivo evaluation can be subdivided into in vitro evaluation and in vivo evaluation. The in vitro evaluation includes carrying out a dissolution test in different mediums to ensure that API is not soluble in saliva but it is soluble in the place of maximum absorption. It also includes testing the final masked formulation using e-Tongues to ensure that the undesirable taste has been hidden.

• The in vivo evaluation is the definitive way of confirming that the unpleasant taste has been hidden as e-Tongues can only give an indication that the unpleasant taste has been hidden. The in vivo evaluation involves using healthy volunteers to calculate bitter taste threshold.

This box summarizes key points contained in the article.

Acknowledgments

Authors would like to thank Ultra Medica (Pharmaceutical Industries) for general support.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper is not funded.