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P L Whyatt

Publications and source records attributed to P L Whyatt.

14 recordsLinked to original sources
PubMed1977

Bioavailability evaluation of an enteric-coated phenylbutazone formulation, and cross-over comparison with a sugar-coated product.

The relative bioavailability of enteric-coated, and commercially available sugar-coated tablets of phenylbutazone (PBZ) was studied in eight healthy volunteers. Each subject received a single oral dose of 400 mg of each preparation in a cross-over sequence. Blood samples were taken for assay of unchanged drug at intervals up to 360 hours. In an attempt fully to characterize the absorption and elimination profiles, three bioavailability parameters were evaluated; peak plasma level of PBZ, time taken to achieve peak level, and area under the plasma level-time curve. Peak plasma levels of PBZ, and area under the plasma level-time curves were not significantly different for the two products, which indicated their bioequivalence. A statistically significant (P is less than 0.001) difference in the rate of absorption of the two products was apparent, since the mean time of occurrence of the peak plasma level of PBZ for the enteric-coated tablets was 9.0 hours compared with 3.9 hours for the sugar-coated formulation. No subjective effects from the two products were noted by any of the subjects, nor were there any alterations in haematological or biochemical parameters.

Adult↗
PubMed1976

Bioavailability of 17 ampicillin products.

The bioavailability of single lots of 250-mg ampicillin capsules, available from 17 distributors and/or manufactures, was determined. Each product was evaluated in terms of the serum ampicillin levels achieved at 1, 2, 3, 4, 6, and 8 hr postadministration, the peak serum levels, the time of peak serum level, and the area under the serum level-time curve. There was no statistically significant difference (p is greater than 0.05) between any of the 17 products tested.

Adult↗
PubMed1976

Bioavailability of 11 sulfisoxazole products in humans.

Single lots of 11 commercially available 500-mg sulfisoxazole tablets were evaluated in vitro and in vivo. All products tested met USP XVIII specifications for weight variation and product assay. However, three products failed to meet the USP XVIII dissolution requirement. The only statistically significant difference observed between the 11 products was a lower peak plasma level exhibited by one product. No useful correlation was observed between the in vivo and in vitro studies for the dosage forms tested.

Adult↗
PubMed1976

Hydrochlorothiazide.

Explore the source record for details and available documents.

Biological Availability↗
PubMed1974

Rapid, precise, turbidometric assay for low levels of ampicillin in serum after single-dose oral administration.

A turbidometric assay is described for the quantitative measurement of ampicillin in serum. Standard curves prepared with known concentrations of ampicillin in serum exhibited acceptable linearity over a concentration range of approximately 0.2 to 1.8 mug/ml. Data are presented to show the excellent precision of the assay and the application of the assay to clinical studies. The advantages of this method over other procedures are discussed. Because of the questionable stability of ampicillin, samples containing known concentrations of ampicillin in serum were assayed after storage for various lengths of time. Serum samples maintained in the frozen state until the time of assay exhibited approximately 12% degradation after 7 days, whereas those samples which were subjected to repeated thawing and refreezing exhibited approximately 25% degradation after the same time interval.

Administration, Oral↗
PubMedDate not supplied

Propoxyphene bioavailability: an evaluation of ten products.

Ten commercial products containing 65 mg propoxyphene hydrochloride have been evaluated for their relative bioavailability in human subjects in a complete crossover study. No statistically significant (P greater than 0.05) differences were observed between the products in terms of plasma levels 1, 2, 3, 4, 6, 8, and 12 hours after administration; peak plasma levels; time to achieve peak plasma level; and area under the plasma level-time curve. Individual subjects exhibited considerable differences in the propoxyphene plasma levels, which were similar to the variability observed by others. The average estimated half-life of 3.61 hours was consistent with previously reported values, although it may have underestimated the true value because the low plasma levels remaining after 12 hours were not quantitated.

Adult↗