A comprehensively validated IVRT method reliably discriminates sameness and differences between several topical clotrimazole creams

In vitro release testing (IVRT) has gained increasing acceptance for use as a biowaiver for topical products intended for local action. Whereas the United States Food and Drug Administration (US FDA) has issued product specific guidances (PSGs) recommending IVRT for several products, the PSG for clotrimazole cream does not include an IVRT option. However, an important requirement to include supplemental selectivity in the validation process as described in the recent FDA draft guidance on IVRT studies for topical drug products has generally been conspicuously absent in the published literature describing the application of IVRT as a biowaiver. Supplemental selectivity involves the comparison of a reference product and altered formulations containing the same strength of the active pharmaceutical ingredient (API). In order to demonstrate supplemental selectivity, cream formulation containing the same API (clotrimazole), at the same strength (1 %) and in the same dosage form (cream) but manufactured using different excipients were used. This will help assess the impact that excipients may have on the release rate of clotrimazole and whether the method is capable of identifying differences in the microstructure and arrangement of matter (Q3) as an important performance parameter. In addition, products containing <30 % or >40 % clotrimazole to serve as negative controls were also included for the discriminatory power assessment. Hence, the primary objective was to develop and validate a simple, reliable, reproducible, and cost-effective in vitro technique in accordance with the recent draft FDA guidance to assess the "sameness" of topical creams containing 1 % clotrimazole. An in vitro release testing (IVRT) system was used and an IVRT method was developed and accordingly validated. The validated IVRT method showed the potential to accurately measure the release from 1 % clotrimazole creams and demonstrated supplemental selectivity and appropriate discriminatory power to identify "sameness" and/ or differences.

A leap towards enforcing medicines prescribing by generic names in low- and middle-income countries (LMICs): pitfalls, limitations, and recommendations for local drug regulatory agencies

The Drug Regulatory Authority of Pakistan (DRAP) in response to the public outcry on increasing medicines prices in the country issued notifications to direct healthcare professionals to prescribe medicines with their generic names. Like DRAP, many regulators in the low- and middle-income countries (LMICs) are also inspiring from the west to legally enforce generic prescribing in a bid to reduce the out-of-pocket public expenditures. However, there are pitfalls in the LMICs drug regulatory framework, which if left unaddressed can severely jeopardise the foreseen benefits of medicines prescribing by generic names. This article critically appraises the impact of prescribing by generic names regulations in LMICs and highlights the key considerations that are vital to address before legally enforcing generic prescribing. The ethics, regulatory compliance, and good governance are the key to success; better generics for a better tomorrow.

BCS-based biowaivers: Extension to paediatrics

A BCS-based biowaiver allows extrapolation of drug product bioequivalence (when applicable) based on the BCS class of the drug and in vitro dissolution testing. Drug permeability and solubility considerations for adult BCS might not apply directly to paediatric subpopulations and bridging of adult and paediatric formulations should be undertaken with caution. The aims of this study were to: (i.) identify compounds which would change drug solubility classification in the paediatric population, and (ii.) to assess the risk of extending BCS-based biowaiver criteria into paediatric products of these compounds. Amoxicillin, prednisolone, and amlodipine were selected as the model compounds. Dissolution studies of IR formulations of these compounds were conducted with USP II (paddle) and mini-paddle apparatus, in media of three pHs (pH 1.2, 4.5 and 6.8). Three dissolution setups were tested: (1) 'typical' BCS-based biowaiver conditions, (2) "BE" setup derived from BE study protocols (volume: 250 mL), and (3) "paediatric" setup based on representative volume for the paediatric population (50 mL). Results revealed that extension of regulated BCS-based biowaiver criteria for paediatric application is not as simple as scaling down volumes. It was further shown that BCS-based biowaiver criteria should not be applied when there is the risk of change of the drug solubility class, from the adult to paediatric populations. A deeper knowledge of the paediatric gastrointestinal environment is still lacking and would assist in refining the biopharmaceutical tools needed to appropriately evaluate formulation performance across age groups. This would potentially reduce the number of clinical studies required and speed up formulation development.

Potential for pharmaceutical excipients to impact absorption: A mechanistic review for BCS Class 1 and 3 drugs

The potential for certain excipients to impact drug absorption is the subject of numerous publications. Reflecting this, current Biopharmaceutics Classification System (BCS) guidelines place restrictions on the level of change in excipients to be eligible for a BCS biowaiver. The degree of change permitted between test and reference formulations varies between BCS Class 1 and 3, and also across different regulatory authorities. This article reviews the literature evidence for excipients to impact drug absorption, with a particular focus on identifying effects which may be important for BCS Class 1 and 3 compounds and formulations. Literature examples were categorised according to the mechanism by which the excipient was believed to impact drug absorption, and the relevance of these mechanisms for compounds within BCS Class 1 and 3 was assessed. The likelihood of using the excipient in solid oral immediate release formulations (i.e. formulation types which would be eligible for BCS biowaivers) was also considered. Using this mechanistic and risk-based approach, potential critical excipients for BCS Class 1 and 3 compounds were identified. Based on the literature data, there are only a limited number of mechanisms by which excipients could affect the absorption of a BCS Class 3 drug. For BCS1, absorption is very unlikely to be affected by excipient changes. For many of these excipients, there is no in vivo evidence of such an effect having occurred. The risk can be mitigated to a large extent by applying some compound-specific understanding of the absorption site, rate and mechanism of the particular API under consideration.