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Comparative bioavailability of three commercial acetaminophen tablets
International Journal of Clinical Pharmacology, Therapy, and Toxicology
|February 1, 1987
Summary
Three acetaminophen tablet brands in Turkey showed comparable in vivo bioavailability despite varying in vitro properties. This suggests that in vitro tests may not always predict in vivo drug absorption for acetaminophen.
Area of Science:
- Pharmaceutical Sciences
- Pharmacokinetics
- Drug Product Quality
Background:
- Acetaminophen is a widely used analgesic and antipyretic.
- Evaluating the quality and bioavailability of generic drug products is crucial for ensuring therapeutic equivalence.
- In vitro dissolution and disintegration tests are commonly used to predict in vivo drug performance.
Purpose of the Study:
- To assess the in vitro properties and in vivo bioavailability of three acetaminophen tablet brands marketed in Turkey.
- To compare the performance of these brands against a standard acetaminophen solution.
- To investigate the correlation between in vitro drug release and in vivo absorption.
Main Methods:
- In vitro evaluation of tablet properties including assay, hardness, diameter, thickness, disintegration, and dissolution.
- In vivo bioavailability study using a single-dose, cross-over design in six healthy volunteers.
- Quantification of urinary acetaminophen excretion using the Welch and Conney colorimetric method.
Main Results:
- No significant differences in manufacturing parameters were found, except for higher variability in Brand A.
- Brand A exhibited slower disintegration and dissolution, failing USP XX standards.
- Relative in vivo bioavailabilities were high and statistically similar across all brands (A: 97.87%, B: 95.41%, C: 98.78%).
Conclusions:
- All three acetaminophen tablet brands demonstrated rapid and near-complete absorption in vivo.
- There is not always a direct correlation between in vitro disintegration/dissolution profiles and in vivo drug bioavailability.
- The study highlights the importance of in vivo bioavailability data for confirming therapeutic equivalence, especially when in vitro results are variable.