The plasma levels of testosterone (T) were measured after oral administration of 25 mg T and 40 mg testosterone-undecanoate (TU) in a group of young women by a specific radioimmunoassay. Plasma levels were compared to those after intravenous administration of 1.5 micrograms testosterone/kg to another group of young women for determination of absolute bioavailability. Due to the high metabolic clearance rate of 24.5 ml/min/kg absolute systemic availability of free testosterone was calculated to 3.56 +/- 2.45%. Oral administration of testosterone undecanoate leads only to an absolute testosterone bioavailability of 6.83 +/- 3.32%.
Six healthy male volunteers received a single topical treatment with 5 g of an anti-acne cream containing 20% azelaic acid (AzA) onto the face, the chest and the upper back. One week later 1 g of AzA was given orally to the same subjects as aqueous microcrystalline suspension. Following the two treatments the renal excretion of the unchanged compound was measured. Analysis included ether extraction of the urine, derivatization of extract and HPLC with UV detection. After topical application 2.2 +/- 0.7%, and after oral administration 61.2 +/- 8.8% of the dose had been excreted unchanged with the urine. By comparing both amounts, the percutaneous absorption of AzA from the cream was assessed to 3.6% of the dermally applied dose.
1. The pharmacokinetics of rolipram were studied in healthy male volunteers using 3H-rolipram and a radioimmunoassay for measurement of unchanged drug. 2. Rolipram was rapidly and completely absorbed after an oral dose of 1 mg. Bioavailability was 73%. 3. Plasma levels of the unchanged drug declined with a terminal half-life of 2 h. The total clearance of rolipram was 2 ml/min per kg. 4. Labelled rolipram was excreted rapidly and completely. The main route of elimination was via the urine.
The percutaneous absorption of diflucortolone-21-valerate (DFV) and its effect on the pituitary adrenal system were investigated during large skin area treatment (20 g ointment twice a day for 8 days) of two groups of healthy volunteers with Nerisona® and Nerisalic® ointment, respectively. Plasma levels of diflucortolone, cortisol and dehydroepiandrosterone (DHEA) were measured in both groups whereas plasma levels of salicylic acid were measured additionally in volunteers treated with Nerisalic. No differences, neither in percutaneous absorption of DFV nor in effects on cortisol and DHEA were found between the two treatment groups. There was a slight reduction in cortisol levels under both treatments, but the circadian rhythm was not disturbed. Mean salicylic acid plasma levels under high-dose topical Nerisalic treatment were about 50-fold below levels where toxicity may be expected.
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