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  • 1
    Electronic Resource
    Electronic Resource
    The Effect of Gelatin Cross-Linking on the Bioequivalence of Hard and Soft Gelatin Acetaminophen Capsules (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 962-966 
    Details
    ISSN: 1573-904X
    Keywords: Gelatin capsules ; acetaminophen ; crosslinking ; dissolution ; human bioequivalence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To determine if changes in the in vitrodissolution of hard and soft gelatin acetaminophen capsules, which resultfrom gelatin crosslinking, are predictive of changes in the bioavailabilityof the capsules in humans. Methods. Both hard and soft gelatin capsules were“stressed” by a controlled exposure to formaldehyde, resultingin unstressed, moderately stressed and highly stressed capsules. invitro dissolution studies were conducted using water or SGF with andwithout pepsin as the media. Separate 24-subject, 3-way crossover humanbioequivalence studies were performed on the unstressed and stressedacetaminophen capsules. Plasma acetaminophen was determined by highperformance liquid chromatography (HPLC) for 12 hr after each dose. Results. The in vitro rate of dissolution of hardand soft gelatin capsules was decreased by crosslinking. The bioequivalencestudies showed that both hard and soft gelatin capsules, which failed tomeet the USP dissolution specification in water, but complied when tested inSGF containing pepsin, were bioequivalent to the unstressed controlcapsules. The capsules that were cross-linked to the greatest extent werenot bioequivalent to the unstressed control capsules, based on Cmax. Atrend toward an increase in Cmax with increased level of cross-linking wasobserved, but this was only significant for the severely stressedcapsules. Conclusions. On the basis of this study a two-tier invitro dissolution test was developed using enzymes to distinguishbetween bioequivalent and bioinequivalent gelatin capsules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007579221726
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  • 2
    Electronic Resource
    Electronic Resource
    Lack of In Vivo/In Vitro Correlations for 50 mg and 250 mg Primidone Tablets (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1085-1089 
    Details
    ISSN: 1573-904X
    Keywords: primidone ; bioavailability ; human ; pharmacokinetics ; in vitro dissolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To determine if large differences in the in vitro dissolution profiles for primidone tablets would result in significant bioavailability differences. Methods. Two separate bioavailability studies were conducted. The first study used 18 healthy subjects and compared the bioavailability of an old 50 mg tablet formulation, a new 50 mg tablet formulation, and a suspension containing 50 mg/ml of primidone. The second study enrolled 24 subjects who were to receive a new 250 mg tablet formulation, two lots of an old 250 mg tablet formulation and a 250 mg tablet from a second manufacturer. In vitro dissolution was conducted over 90 minutes, using USP 23 Apparatus 2 at 50 rpm, with 900 ml of water. Results. Dissolution at 90 minutes for the old and new 50 mg tablets was approximately 20% and 100%, respectively. The dissolution of the four 250 mg tablets ranged from approximately 30% to 100%. The 50 mg tablet that dissolved slower had a longer Tmax and a 14% lower Cmax than the more rapidly dissolving tablet, but the AUC(0−∞) values differed by only 3%. Only nine subjects completed the 250 mg study because of side effects. The differences in Cmax and AUC(0−∞) among the four 250 mg tablets were less than 7%. Conclusions. Even though there were large differences in the in vitro dissolution of the 50 mg and the 250 mg primidone tablets, the two 50 mg tablets were shown to be bioequivalent, as were the four 250 mg tablets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011942530288
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  • 3
    Electronic Resource
    Electronic Resource
    The Relative Bioavailability and In Vivo-In Vitro Correlations for Four Marketed Carbamazepine Tablets (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1787-1791 
    Details
    ISSN: 1573-904X
    Keywords: carbamazepine ; human ; bioavailability: gender, dissolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To determine if three marketed generic carbamazepine tablets were bioequivalent to the innovator formulation, as well as to each other. In addition, to examine in vivo-in vitro relationships among the four formulations. Methods. Each formulation was given as a single dose to 18 healthy male and female subjects using a crossover design. Blood samples were collected for 169 hr. Carbamazepine was assayed by HPLC with UV detection. Results.In vivo fraction absorbed plots indicated that the three generic formulations were absorbed more rapidly than the innovator product, and the mean time of maximum plasma concentration was 6−7 hr sooner for the generic formulations. The mean maximum plasma concentration ranged from 17−19 percent higher for the generic products compared to the innovator, and the 90% confidence limits for Cmax data ranged from 111% to 126%. The mean AUC(0−∞) for the generic products ranged from 101−104% compared to the innovator, and the confidence limits for AUC ranged from 97−108%. Conclusions. The generic products were all more rapidly absorbed than the innovator, but simulations of steady-state concentrations indicated that it would be unlikely that these differences would have any significant clinical effect. An excellent association was seen between the Cmax and the percent of drug dissolved in vitro. The correlation was used to accurately predict the Cmax of four other 200 mg tablets evaluated in an earlier study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011929300613
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