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At least 235 records · Page 13Linked to original sources
PubMed1975

Biopharmaceutic factors in parenteral administration of vitamin E.

When properly formulated, micellar-type aqueous dispersions of tocopheryl acetate are administered intravenously or intramuscularly to dogs, the rate-limiting step in the bioavailability of the physiologically active free tocopherol is the rate of hydrolysis of the acetate ester. A similar dispersion of free tocopherol yields blood levels of tocopherol many fold higher than those obtained with the acetate ester after intravenous injection and also yields much greater increases in blood levels of free tocopherol after intramuscular injection than the acetate ester formulation, particularly in the early period after the dose.

Acetates↗
PubMed1977

Biopharmaceutic factors that influence effects of anticholinergic drugs: comparison of propantheline, hexocyclium, and isopropamide.

The antisecretory (determined from salivary flow rates) and antimotility (determined from riboflavin absorption) effects of usually recommended doses of propantheline, hexocyclium, and isopropamide were compared in four adult volunteers. Both propantheline and hexocyclium significantly decreased salivary flow and increased riboflavin absorption. Although the usual dose of propantheline was about twice as effective as the usual dose of hexocyclium in suppressing salivary flow, these doses produced comparable effects on riboflavin absorption. Isopropamide had little or no effect on either the salivary flow rate or riboflavin absorption. Propantheline and hexocyclium elicited little effect on salivary flow when administered after a meal. Prolonged-release dosage forms of these drugs produced effects comparable to those produced by much smaller doses in conventional tablets and gave no indication of providing prolonged anticholinergic effects.

Adult↗
PubMed1983

Use of isosorbide dinitrate saliva concentrations for biopharmaceutical investigations.

The concentration of isosorbide dinitrate in paired samples of plasma and mixed saliva was monitored for up to 24 hr after oral administration of 60 mg of sustained-release isosorbide dinitrate to eight healthy volunteers. Measured isosorbide dinitrate plasma concentrations were mainly in the range of 0.1-10 ng/ml. Isosorbide dinitrate was excreted into saliva resulting in a mean (+/- SD) saliva-plasma concentration ratio of 0.68 +/- 0.37. A significant correlation between concentrations of isosorbide dinitrate in saliva and plasma was found (p less than 0.01). The sustained-release properties of the administered formulation were confirmed from the concentrations of isosorbide dinitrate found in both saliva and plasma. Saliva-plasma ratios were independent of the absolute concentrations of isosorbide dinitrate but showed a slight tendency to decrease with time. The principal factor relating saliva and plasma isosorbide dinitrate concentrations appeared to be the degree of plasma protein binding of the drug.

Adolescent↗
PubMedDate not supplied

In vitro/in vivo correlations in biopharmaceutics: scientific and regulatory implications.

This paper explains the regulatory and scientific reasons for the regulatory authorities employing dissolution as a key variable for regulatory approval of batch to batch bioequivalence assurance, site of manufacture change, formulation changes, and batch size scale-up for immediate release dosage forms. It also explains the scientific and regulatory reasons why either an in vivo/in vitro correlation using USP's Level 'A', 'B' or 'C', or a newly proposed 'mapping' approach will be required for allowing such changes for controlled-release dosage forms.

Biopharmaceutics↗
PubMed1997

A case study and use of sedimentation equilibrium analytical ultracentrifugation as a tool for biopharmaceutical development.

Analytical ultracentrifugation (AUC) has reemerged as a powerful technique for protein characterisation. We report the pivotal role sedimentation equilibrium AUC has played in the development of macrophage inflammatory protein-1 alpha (MIP-1 alpha) as a protein therapeutic. MIP-1 alpha has potential clinical applications in cancer but its clinical use is limited, since it associates to form large insoluble aggregates in physiological buffers. Using AUC as a screening technique, we have produced a biologically active variant of MIP-1 alpha, BB-10010, which has a reduced tendency to aggregate in physiological buffers. The aggregation of protein based pharmaceuticals is routinely monitored by size exclusion chromatography (SEC). Comparison of the data acquired by SEC and AUC, demonstrates that owing to the complexity of BB-10010, AUC analysis is required in addition to SEC to provide a rigorous characterisation of molecular association. This work has been extended to include the use of AUC as an analytical tool to monitor the quality of BB-10010 during formulation and stability studies.

Biopharmaceutics↗