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Vinod P Shah

Publications and source records attributed to Vinod P Shah.

14 recordsLinked to original sources
PubMed2007

Conference report: Bio-International 2005.

This is a summary report of the International Pharmaceutical Federation/Board of Pharmaceutical Sciences (FIP/BPS) international conference, Bio-International 2005, which was held October 24-26, 2005 at the Royal Pharmaceutical Society, in London, UK. Bioequivalence (BE) issues related to multisource locally delivered topical dosage forms, oral inhalation drug products, highly variable drug products (HVDP), and endogenously occurring drugs were discussed. The conference also focused on alternate approaches to assess BE for some of these drug products. Pharmacokinetic (PK) approaches like, dermatopharmacokinetics (DPK) for dermatological topical dosage forms, scaled average BE (s-ABE) where within-subject variability is considered for estimation of 90% confidence intervals to document BE for highly variable drugs (HVD) were recommended. In addition, issues and difficulties related to the BE assessment of oral inhalation products, role, and appropriateness of metabolites in BE assessment, importance of base line correction in BE assessment of endogenously occurring drugs, and waiver of BE study requirements for certain drugs based on a Biopharmaceutics Classification System (BCS), were also discussed.

Administration, Inhalation↗
PubMed2006

Bioequivalence of topical formulations in humans: evaluation by dermal microdialysis sampling and the dermatopharmacokinetic method.

The aim of this study was to evaluate the relationship between dermal microdialysis (DMD) sampling and the dermatopharmacokinetic method when employed simultaneously for bioequivalence (BE) investigations of topical formulations. Topical lidocaine cream and ointment (both 5%) was investigated in eight healthy human volunteers (four male, four female). On one forearm, four microdialysis probes in two penetration areas sampled for 5 hours, and on the other arm, tape stripping was performed 30 and 120 minutes after product application. Lidocaine content in samples was analyzed by HPLC-mass spectrometry. The two methods were in agreement showing 3- to 5-fold higher lidocaine penetration from cream formulation than from ointment. A rank-order correlation between the two methods was demonstrated for lidocaine contents in microdialysates versus tape strip at 120 minutes, significant for the ointment formulation and for both formulations analyzed together. Analysis of variance demonstrated reproducible lidocaine concentrations in microdialysates with an intrasubject variability of 19% between probes and 20% between the two penetration areas. Thus, intersubject variability accounted for 61% of the variance. DMD sampling proved effective and variability analyses demonstrated the feasibility of BE studies in as little as 18 subjects.

Administration, Topical↗
PubMed2005

IV-IVC for topically applied preparations--a critical evaluation.

In vitro-in vivo correlation (IV-IVC) is the relationship between an in vitro parameter (drug release or other rheological properties/measurement such as viscosity and spreadability) and an in vivo parameter (pharmacodynamic (PD) or dermatopharmacokinetic (DPK) or other measurement). In a true sense of correlation, in vitro measurement should predict in vivo performance of the product. For topically applied preparations, one of the in vitro measurements is the drug release from the formulation and in vivo measurement is the drug concentration in the stratum corneum, DPK or the PD measurements. The in vitro release of the drug is the property of the dosage form and is a measure of product quality and 'sameness', especially after certain Scale-UP and Post Approval Changes after initial drug approval. To obtain an IV-IVC for a topically applied drug product is a difficult challenge. However, some success has been achieved in showing a relationship between the drug release and PD and/or DPK measurement. Interestingly, one of the in vitro rheological properties was found to relate to the observed PD and DPK response for Clobetasol dipropionate products. Different rheological properties of the two formulation products explained the difference in DPK results obtained by two laboratories for the same tretinoin gel products. In the scientific arena, it is difficult to obtain a classical IV-IVC even for orally administered products and is more so difficult for topically administered drug products.

Administration, Topical↗
PubMed2004

Molecular properties of WHO essential drugs and provisional biopharmaceutical classification.

The purpose of this study is to provisionally classify, based on the Biopharmaceutics Classification System (BCS), drugs in immediate-release dosage forms that appear on the World Health Organization (WHO) Essential Drug List. The classification in this report is based on the aqueous solubility of the drugs reported in commonly available reference literature and a correlation of human intestinal membrane permeability for a set of 29 reference drugs with their calculated partition coefficients. The WHO Essential Drug List consists of a total of 325 medicines and 260 drugs, of which 123 are oral drugs in immediate-release (IR) products. Drugs with dose numbers less than or equal to unity [Do = (maximum dose strength/250 mL)/solubility < or = 1] are defined as high-solubility drugs. Drug solubility for the uncharged, lowest-solubility form reported in the Merck Index or USP was used. Of the 123 WHO oral drugs in immediate-release dosage forms, 67% (82) were determined to be high-solubility drugs. The classification of permeability is based on correlations of human intestinal permeability of 29 reference drugs with the estimated log P or CLogP lipophilicity values. Metoprolol was chosen as the reference compound for permeability and log P or CLogP. Log P and CLogP were linearly correlated (r2 = 0.78) for 104 drugs. A total of 53 (43.1%) and 62 (50.4%) drugs on the WHO list exhibited log P and CLogP estimates, respectively, that were greater than or equal to the corresponding metoprolol value and are classified as high-permeability drugs. The percentages of the drugs in immediate-release dosage forms that were classified as BCS Class 1, Class 2, Class 3, and Class 4 drugs using dose number and log Pwere as follows: 23.6% in Class 1, 17.1% in Class 2, 31.7% in Class 3, and 10.6% in Class 4. The remaining 17.1% of the drugs could not be classified because of the inability to calculate log P values because of missing fragments. The corresponding percentages in the various BCS classes with dose number and CLogP criteria were similar: 28.5% in Class 1, 19.5% in Class 2, 35.0% in Class 3, and 9.8% in Class 4. The remaining 7.3% of the drugs could not be classified since CLogP could not be calculated. These results suggest that a satisfactory bioequivalence (BE) test for more than 55% of the high-solubility Class 1 and Class 3 drug products on the WHO Essential Drug List may be based on an in vitro dissolution test. The use of more easily implemented, routinely monitored, and reliable in vitro dissolution tests can ensure the clinical performance of drug products that appear on the WHO Essential Medicines List.

Administration, Oral↗
PubMed2004

Determination of the formation of the stratum corneum reservoir for two different corticosteroid formulations using tape stripping combined with UV/VIS spectroscopy.

BACKGROUND: The stratum corneum, the outermost layer of the skin, not only represents a barrier, but also a reservoir for topically applied substances. Both properties influence the penetration process, as does the vehicle. It determines the penetration pathway and the retention time of the topically applied substances. METHODS: Two commercial products (Temovate Cream and Temovate Emollient), both containing 0.05% clobetasol propionate, were applied on the inner forearms of healthy volunteers. 20 tape strips were removed from each treated skin area. The horny layer profile was determined measuring the absorption of the corneocytes at 430 nm. The concentration of clobetasol propionate on the individual tapes was then analyzed. RESULTS: We found differences in the reservoir formation depending on the formulation applied, which correlated to the biological response in the form of a blanching effect. CONCLUSIONS: The method applied is well-suited to determine the reservoir formation in the stratum corneum for topically applied substances.

Administration, Topical↗
PubMed2004

Three-stage sequential statistical dissolution testing rules.

The U.S. Pharmacopoeia (USP) general monograph provides a standard for dissolution compliance with the requirements as stated in the individual USP monograph for a tablet or capsule dosage form. The USP monograph sets performance limit on dissolution in terms of a specific percentage Q that the drug product is required to be dissolved at a specified time. Japan Pharmacopoeia provides acceptance rules different from USP. However the objective of the acceptance rules was not defined in terms of the inference of the whole lot by either USP, European Pharmacopoeia (EP) or Japan Pharmacopoeia (JP). The operating characteristics' curves of these rules are all shown to be sensitive to the true mean dissolution and do not reject a lot which has a large percentage of tablets that dissolve with less than the specified limit Q. This is especially true when the mean dissolution is close to the specification value. We proposed that the goal of the dissolution test sampling plan is to accept a lot at least 90% of the tablets dissolved more than a pre-specified amount Q at the specific time. The group sequential procedure derived accordingly is shown to outperform both USP and JP in controlling the type I error rate under normality assumption.

Algorithms↗
PubMed2003

Assessment of dermatopharmacokinetic approach in the bioequivalence determination of topical tretinoin gel products.

BACKGROUND: A new dermatopharmacokinetic (DPK) approach has been proposed for bioequivalence determination of topical drug products by comparing the drug content kinetics in stratum corneum. OBJECTIVE: We sought to establish any correlation between clinical safety/efficacy and DPK approach in bioequivalence determination of tretinoin gel 0.025%. METHODS: Tretinoin and isotretinoin were quantified in human volar forearm stratum corneum as a function of time with 3 tretinoin gel 0.025% products in 49 patients. Stratum corneum layers were harvested using multiple adhesive disks, which were subsequently extracted and quantified for both isomers by high-performance liquid chromatography. RESULTS: Products with similar composition and therapeutic equivalence were found bioequivalent, and products with different composition and clinical profiles were found bioinequivalent by DPK methodology. CONCLUSIONS: There is a direct correlation between DPK parameters in healthy patients and clinical safety/efficacy of tretinoin gel products in patients with acne. Data support the use of DPK parameters and methodology in the bioequivalence assessment of topical tretinoin gel products.

Administration, Topical↗
PubMed2003

In vitro release: comparative evaluation of vertical diffusion cell system and automated procedure.

In vitro release for topical drug products is carried out using a vertical diffusion cell system and a synthetic support membrane. The improvements in vertical diffusion cell design and automated procedures have been carefully studied and evaluated to establish their reproducibility and ruggedness of the experimental procedure. The data were analyzed using 90% confidence interval procedure developed and published by the US Food and Drug Administration in SUPAC-SS (Start Up and Post Approval Changes-Semi Solid) guidance.

Diffusion Chambers, Culture↗
PubMed2002

Comparison of skin stripping, in vitro release, and skin blanching response methods to measure dose response and similarity of triamcinolone acetonide cream strengths from two manufactured sources.

The collective studies compare in vitro drug release, in vivo skin stripping, and skin blanching response methods for dose responsiveness and bioequivalence assessment of triamcinolone acetonide cream products, as a function of application duration, drug concentration, and manufacturer source. Commercially available triamcinolone acetonide creams (0.025%, 0.1%, and 0.5%) from two manufacturers were evaluated in vitro for rate and extent of drug release across synthetic membranes and in vivo for rate, extent, and variability of drug uptake into human stratum corneum and skin blanching response in human forearm skin. Data demonstrate that increasing triamcinolone acetonide cream concentration applied increased the rate and extent of drug released in vitro as well as the extent of drug uptake and skin blanching response in human skin in vivo. No difference (p < 0.05) between the two sources of 0.1% or 0.5% creams was measured by the skin stripping or skin blanching response methods. Dermatopharmacokinetic analysis of triamcinonide acetonide in vivo is therefore dose responsive to drug concentration applied and application duration and agrees with in vivo skin blanching results. Data support the use of dermatopharmacokinetic methods for bioequivalence and bioavailability assessment of topical drug products.

Administration, Topical↗
PubMed2002

Variability in cimetidine absorption and plasma double peaks following oral administration in the fasted state in humans: correlation with antral gastric motility.

The role of gastrointestinal motility and pH in determining cimetidine bioavailability as well as double peaks in plasma profiles following oral administration, in the quiescent or active phase of antral motility, to humans in the fasted state was examined. Plasma cimetidine-time curves did not show the presence of double peaks in any subject following intravenous administration. The incidence of double peaks was 73% following oral administration and was independent of antral migrating motility complex phase. Further, it was found that oral administration of cimetidine in the quiescent phase resulted in significantly higher bioavailability and in other pharmacokinetic parameters compared to that obtained following administration in the active phase. Excellent linearity in plots of motility peaks vs. plasma peaks with slopes close to unity were evident for both quiescent (r(2)=0.93) and active phase (r(2)=0.97) administration. A total of 14 peaks out of 22 (10 subjects, 64%) and 20 out of 27 peaks (11 subjects, 74%), were accounted for in quiescent and active phase oral administration, respectively. The proximal occurrence of plasma peaks to antral motility peaks typical of phase III contractions strongly implies that motility patterns may be responsible for secondary maxima following oral cimetidine administration in the fasted state.

Administration, Oral↗
PubMed2002

Biopharmaceutics classification system: the scientific basis for biowaiver extensions.

The current BSC guidance issued by the FDA allows for biowaivers based on conservative criteria. Possible new criteria and class boundaries are proposed for additional biowaivers based on the underlying physiology of the gastrointestinal tract. The proposed changes in new class boundaries for solubility and permeability are as follows: 1. Narrow the required solubility pH range from 1.0-7.5 to 1.0-6.8. 2. Reduce the high permeability requirement from 90% to 85%. The following new criterion and potential biowaiver extension require more research: 1. Define a new intermediate permeability class boundary. 2. Allow biowaivers for highly soluble and intermediately permeable drugs in IR solid oral dosage forms with no less than 85% dissolved in 15 min in all physiologically relevant dissolution media, provided these IR products contain only known excipients that do not affect the oral drug absorption. The following areas require more extensive research: 1. Increase the dose volume for solubility classification to 500 mL. 2. Include bile salt in the solubility measurement. 3. Use the intrinsic dissolution method for solubility classification. 4. Define an intermediate solubility class for BCS Class II drugs. 5. Include surfactants in in vitro dissolution testing.

Biopharmaceutics↗
PubMed2002

Novel metrics to compare dissolution profiles.

PURPOSE: To evaluate four novel metrics that compare dissolution profiles and assess their performance characteristics by comparing dissolution profiles of FAST and SLOW immediate release metoprolol tartrate tablets. METHODS: The four novel metrics (rho, rho m, delta a, and delta s), along with f2, were applied to dissolution data from FAST and SLOW metoprolol tartrate tablets. For example, rho m is defined as: [formula: see text] where Rt is the percent dissolved of the reference product at time t, Tt the percent dissolved of the test product at time t, and RATIOt the larger of either Rt/Tt or Tt/Rt. The mean metric values, upper (or lower) confidence limits, and skewness values were calculated, in order to characterize the performance of each metric. RESULTS: The mean values of rho, rho m, delta a, delta s, and f2 were 1.80, 0.80, 0.47, 0.36, and 19.6, respectively. The novel metrics indicate that greater than a 50% relative difference exists between the FAST and SLOW profiles. The upper 95% confidence limits for rho, rho m, delta a, and delta s were 1.84, 0.83, 0.48, and 0.38, respectively, with f2 having a lower limit of 19.1. Skewness values for ln-transformed rho, rho m, delta a, delta s, and f2 were 0.81, 0.71, 0.86, 0.47, and -0.94, respectively, suggesting favorable metric distribution properties. CONCLUSIONS: The direct curve comparison metrics rho, rho m, delta a, and delta s appear to be viable methods to compare dissolution profiles, particularly rho m.

Mathematics↗