To Maintain Formulation Composition Similarity of Coated Tablets of Different Strengths: Should Coating be Based on Core Tablet Weight or Surface Area?

PURPOSE: As per the Japanese or SUPAC guidance to maintain formulation composition similarity across tablet strengths, the coating should be applied based on the core tablet surface area or weight, respectively. These two coating approaches were compared by evaluating protective effects of coating on the light stability of three model compounds. METHODS: Core tablets of three light sensitive drugs, nifedipine, rosuvastatin calcium, and montelukast sodium were coated either with PVA-based Opadry® II white or Opadry® II beige. The coated tablets were exposed to light up to three ICH cycles. RESULTS: For Opadry® II white, the surface area based coating provided consistent light protection across tablet strengths when the coating amount was more than 0.1 mg/mm2 compared to that based on core tablet weights. For Opadry® II beige, both approaches gave comparable and better light protection due to presence of iron oxides. The light protection by Opadry® II white could be because of physical barrier of coating, which was uniform across the strengths when it was based on core tablet surface area. CONCLUSION: For a routine tablet formulation development with Opadry color coating, it does not matter whether the coating is applied based on the core tablet surface area or weight.

In vitro release test (IVRT): Principles and applications.

In vitro drug release test has become one of the most important tools for drug development and approval process of semisolid dosage forms. In vitro release test (IVRT) has the ability to reflect the combined effects of several physicochemical characteristics, particle or droplet size, viscosity, microstructure arrangement of the matter and state of aggregation of dosage form. Genesis of IVRT, its principles and rank order relationship with pharmacodynamic response such as vasoconstriction or dermatopharmacokinetic (skin stripping) results and the evolution of test requirements for regulatory approval is discussed. IVRT reflects various parameters and is an essential part of the stepwise approach to compare topical formulation and its ability to release active in similar quantity at similar rate. Therefore, it is an essential tool, in addition to similar qualitative and quantitative composition (Q1 Q2), to assess the similarity of microstructural arrangement (Q3) as proposed in the Topical drug Classification System (TCS) approach of classes 1 and 3. The TCS system along with evolving concept for topical dermatological drug products from Q1, Q2, Q3 sameness to Q1, Q2, Q3 similar allowing greater permissiveness in formulation changes is discussed.

A Validated IVRT Method to Assess Topical Creams Containing Metronidazole Using a Novel Approach.

An IVRT method was developed and validated to confirm its reproducibility, precision, sensitivity, selectivity, accuracy, robustness, and reliability. A novel approach was used to demonstrate the appropriateness of the IVRT method to accurately assess "sameness" between topical products and to confirm that the methodology applied also possesses the requisite discriminatory power to detect differences should such differences exist between products. In the first instance, the reference product (Metrocreme®) containing 0.75% metronidazole (MTZ) was tested against itself as a positive control, to accurately demonstrate "sameness", where the results met the relevant acceptance criteria falling within the limits of 75-133.33% in accordance with the FDA's SUPAC-SS guidance. In addition, two specially prepared creams containing 25% less and 26% more MTZ, i.e., 0.563% and 0.945%, served as negative controls and were compared against the reference product. Neither of these creams fell within the "sameness" acceptance criteria, thereby confirming the discriminatory ability of the IVRT method to detect differences between MTZ products. Furthermore, another cream containing 0.75% MTZ tested against the reference product was shown to be pharmaceutically equivalent to the reference product. These results confirm the appropriateness of the IVRT method as a valuable tool for use in the development of topical MTZ products intended for local action and indicate the potential for general use with other topical products.

Approaches for Establishing Clinically Relevant Dissolution Specifications for Immediate Release Solid Oral Dosage Forms.

This manuscript represents the perspective of the Dissolution Analytical Working Group of the IQ Consortium. The intent of this manuscript is to highlight the challenges of, and to provide a recommendation on, the development of clinically relevant dissolution specifications (CRS) for immediate release (IR) solid oral dosage forms. A roadmap toward the development of CRS for IR products containing active ingredients with a non-narrow therapeutic window is discussed, within the context of mechanistic dissolution understanding, supported by in-human pharmacokinetic (PK) data. Two case studies present potential outcomes of following the CRS roadmap and setting dissolution specifications. These cases reveal some benefits and challenges of pursuing CRS with additional PK data, in light of current regulatory positions, including that of the US Food and Drug Administration (FDA), who generally favor this approach, but with the understanding that both industry and regulatory agency perspectives are still evolving in this relatively new field. The CRS roadmap discussed in this manuscript also describes a way to develop clinically relevant dissolution specifications based primarily on dissolution data for batches used in pivotal clinical studies, acknowledging that not all IR product development efforts need to be supported by additional PK studies, albeit with the associated risk of potentially unnecessarily tight manufacturing controls. Recommendations are provided on what stages during the life cycle investment into in vivo studies may be valuable. Finally, the opportunities for CRS within the context of post-approval changes, Modeling and Simulation (M&S), and the application of biowaivers, are briefly discussed.

Understanding peroral absorption: regulatory aspects and contemporary approaches to tackling solubility and permeability hurdles.

Oral drug absorption is a process influenced by the physicochemical and biopharmaceutical properties of the drug and its inter-relationship with the gastrointestinal tract. Drug solubility, dissolution and permeability across intestinal barrier are the key parameters controlling absorption. This review provides an overview of the factors that affect drug absorption and the classification of a drug on the basis of solubility and permeability. The biopharmaceutical classification system (BCS) was introduced in early 90׳s and is a regulatory tool used to predict bioavailability problems associated with a new entity, thereby helping in the development of a drug product. Strategies to combat solubility and permeability issues are also discussed.

The Gradually Expanding Scope for Biowaivers of Oral Products: An Overview.

The regulatory paradigm is relaxing gradually without compromising the safety, efficacy and the quality of the drug product and, most importantly, a perceptible scientific consensus is maturing towards the need of affordable medicines. The establishment of bioequivalence (BE) is no longer being considered to be accomplished only by in vivo studies in oral drug products. The potential use of in vitro dissolution testing in lieu of BE studies has now been regulatory adopted and is commonly referred to as "biowaiver". Further, the advent of biopharmaceutics classification system (BCS) and in vitro-in vivo correlation (IVIVC) proves to be sound milestones and signifies that we are incessantly forwarding towards a scenario that would reduce regulatory burden, save time and make the drug products more affordable while ensuring their quality. This review outlines, the current and pertinent regulatory environment for biowaiver based on in vitro drug dissolution, primarily as per the FDA perspective. The rationale used for qualification of biowaiver for different strengths, post-approval changes and multi-source products are discussed along with the role of BCS and IVIVC.

Pharmaceutical excipients - quality, regulatory and biopharmaceutical considerations.

Practically all medications contain excipients, which are added for the purpose of production enhancement, patient acceptability, improving stability, controlling release etc. Typically excipients are the major components of a drug product, with the active molecule only present in relatively small amounts. Historically, excipients were termed inactive components. However, as highlighted in the present paper; excipients can have an impact on the absorption, distribution, metabolism and elimination (ADME) processes of the co-administered drug, which is important information when selecting excipients for any new formulation. Further, this review also provides a description of the regulatory processes to get new excipients approved in different regions and a discussion of the recent regulatory initiatives, e.g. excipients for paediatric formulations, thereby providing points to consider for the pharmaceutical scientist when selecting excipients for a new drug formulation.

A science based approach to topical drug classification system (TCS).

The Biopharmaceutics Classification System (BCS) for oral immediate release solid drug products has been very successful; its implementation in drug industry and regulatory approval has shown significant progress. This has been the case primarily because BCS was developed using sound scientific judgment. Following the success of BCS, we have considered the topical drug products for similar classification system based on sound scientific principles. In USA, most of the generic topical drug products have qualitatively (Q1) and quantitatively (Q2) same excipients as the reference listed drug (RLD). The applications of in vitro release (IVR) and in vitro characterization are considered for a range of dosage forms (suspensions, creams, ointments and gels) of differing strengths. We advance a Topical Drug Classification System (TCS) based on a consideration of Q1, Q2 as well as the arrangement of matter and microstructure of topical formulations (Q3). Four distinct classes are presented for the various scenarios that may arise and depending on whether biowaiver can be granted or not.