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Biomedical subjects

P Kahela

Publications and source records attributed to P Kahela.

10 recordsLinked to original sources
PubMed1990

The influence of ageing on the release of hydrocortisone from o/w creams.

The influence of ageing on the release of hydrocortisone from o/w creams containing ionic and nonionic emulgators and different amounts of water was investigated over a period of 48 weeks. The influence of ageing was dependent on the type of emulgator and the amount of water in the cream. Up to 12 weeks of storage, ageing affected the creams containing ionic emulgators by retarding the release of hydrocortisone; after that, hydrocortisone release was enhanced and the release profile also changed. For the creams containing 60% water, the effects of ageing differed slightly from the creams containing 40% or 80% water. These findings can be explained by particle growth and agglomeration but changes in the microstructure of the creams may also be important. Creams containing nonionic emulgators were only slightly affected by ageing.

Animals↗
PubMed1989

Effect of water content and type of emulgator on the release of hydrocortisone from o/w creams.

The release of hydrocortisone was determined in vitro from o/w-creams containing an anionic (sodium lauryl sulphate), a cationic (cetrimide) or a nonionic (cetomacrogol 1000) surfactant as emulgator and different amounts of water. The solubility of hydrocortisone in water-emulgator systems and the solubilizing capacity of these emulgators for hydrocortisone were also determined. The release of hydrocortisone from creams containing emulgators increased in the same order as the solubilizing capacity of these emulgators for hydrocortisone, which indicates how important the concentration of dissolved hydrocortisone in the cream is for release. The effect of water content on the release of hydrocortisone was also dependent on the emulgator used. With a nonionic emulgator, release was enhanced slightly as the water content in the cream increased. In the case of ionic emulgators, release of hydrocortisone was retarded as the amounts of water in the cream increased up to 60% water content; above this, the release was enhanced, probably owing to changes in the liquid crystalline microstructure of the cream.

Emulsions↗
PubMed1988

The absorption of acetylsalicylic acid from an enteric-coated formulation and the inhibition of thromboxane formation.

To compare conventional (CT) and enteric-coated (ECT) tablets of acetylsalicylic acid (ASA) six healthy adult subjects ingested one 0.5-g tablet of these formulations daily for fifteen days in a cross-over study. Significant amount of ASA was detected in peripheral blood of every subject after the ingestion of CT or ECT. The rate of absorption of ASA was faster and its peak plasma concentration was higher after the ingestion of CT. The formation of thromboxane B2 (TXB2) decreased during blood clotting concomitantly with the absorption of ASA from both formulations. The formation of TXB2 was equally and completely inhibited by CT and ECT as it decreased to 1% of the control value one day after the first dose. During treatment with a single daily dose of 0.5 g of CT or ECT, the serum level of TXB2 remained at this low level and returned to the control level gradually in two weeks after the last dose. The present study indicates that significant amount of unchanged ASA is absorbed also from ECT and that the formation of TXB2 is equally and completely inhibited with a 0.5-g daily dose of both formulations.

Adult↗
PubMed1983

Comparison of three slow-release acetylsalicylic acid preparations in rheumatoid arthritis.

Nine patients suffering from chronic rheumatoid arthritis were each given single doses of 1 g acetylsalicylic acid, in the form of each of the preparations studied: an enteric-coated tablet, a microcrystalline tablet, and a capsule containing enterosoluble granules. Absorption from each preparation was good in all patients. Onset of absorption varied to some degree, but similar salicylate levels were reached within 5 hours with all preparations. In the case of enteric-coated tablets, relatively high salicylate levels persisted 12 hours after dosing, which would seem to permit twice daily dosage, regardless of the total daily dose.

Adult↗
PubMed1981

Antacids and sotalol absorption.

The effect of concurrent administration of antacids on the relative bioavailability of sotalol has been examined in five healthy volunteers. Each subject received an oral 160 mg dose after an overnight fast in four different experimental schedules. Venous blood samples were drawn 1, 2, 3, 4, 5, 6, 7, 8, 12, 24, and 32 hours after the drug administration, and sotalol concentrations were determined fluorometrically. The results show that concurrent administration of calcium carbonate or aluminum hydroxide with sotalol has negligible pharmacokinetic consequences. The adsorption of sotalol onto magnesium hydroxide leads to somewhat decreased bioavailability but in long term use the phenomenon is not likely to be of clinical importance.

Adsorption↗
PubMed1979

Comparative bioavailability of two commercial preparations of carbamazepine tablets.

A comparative bioavailability study was performed using two commercially available types of carbamazepine tablets, by statistical analysis of serum levels and other bioavailability parameters. After single oral dose the extent of absorption from the two preparations was similar, although a statistically significant difference in absorption rates was observed. In a multiple-dose study no significant difference in serum carbamazepine levels was found, so the tablets could be considered as bioequivalent drug products.

Adult↗
PubMed1979

Effect of food, food constituents and fluid volume on the bioavailability of sotalol.

The effect of food, some food constituents, and large volumes of fluid taken with the drug on the relative bioavailability of sotalol has been examined in five healthy volunteers. Each subject received an oral 160 mg dose in six different experimental schedules. Venous blood samples were drawn 1, 2, 3, 4, 6 and 8 hrs after the dosing, and sotalol concentrations in serum were determined fluorometrically. The results indicate that large volumes of fluid delay but do not affect the extent of sotalol absorption. Food, especially milk, decreases the bioavailability of the drug and an interaction with calcium seems to be the major reason for the reduced absorption.

Administration, Oral↗