Ageing and free radical formation. A biochemical approach to evaluate the efficacy of cosmetic preparations.

Synopsis A new method is described for studying the in vivo formation of oxygen reactive species (free radicals) in humans after exposure to UV radiation. The procedure is based on the quantitative determination in urine of (i) metabolic products of pentane, a hydrocarbon formed during lipid peroxidation, and (ii) thymine hydroxylated bases and deoxyribonucleosides as indices of DNA repair that has taken place. Creams containing UV filters protect the organism against free radical formation.

Metabolism of caffeine to 6-amino-5-[N-methylformylamino]-1,3-dimethyluracil in the isolated, perfused liver from control or phenobarbital-, beta-naphthoflavone- and 3-methylcholanthrene-pretreated rats.

Caffeine metabolism to 6-amino-5-[N-methylformylamino]-1,3-dimethyluracil was studied in the isolated, perfused rat liver. The [2-14C]-labelled drug and metabolites were separated by thin-layer chromatography or high-pressure liquid chromatography. The chemical structure of 6-amino-5-[N-methylformylamino]-1,3-dimethyluracil was confirmed by mass spectrometry and it was quantitatively determined by liquid scintillation counting.

Indenolol kinetics versus pharmacodynamics in hypertension.

A kinetic model has been employed to compare the duration of the antihypertensive activity of indenolol to its plasma half-life both after single administration and at steady-state. After a 14 day run-in period with placebo, 60 or 120 mg indenolol were given to hypertensive patients I or II grade, according to W.H.

Different sensitivity of two Walker 256 carcinoma lines to cyclophosphamide: correlation with drug distribution, biotransformation and macromolecule binding.

Two closely related lines of the same Walker 256 carcinoma in Crl-CD/COBS rats, described as behaving differently as regards tumor growth and host reaction, show different chemotherapeutic sensitivity to cyclophosphamide (CPA). Line B, which induces early cachexia with marked anorexia, is only moderately sensitive to CPA, while line A, which causes mild anorexia and only terminal cachexia, shows marked responsiveness to CPA, cure being attained in 75% of animals treated with a single dose of 120 mg/kg and in 90-100% of those given 20 mg/kg every other day. Comparative studies in both tumor lines on the distribution of CPA in vivo and on its metabolism by the liver perfusion technique showed no appreciable differences between the two lines in the pharmacokinetics of the compound, but indicate a much greater metabolizing capacity of CPA in the Walker 256/A animals.

Indenolol pharmacokinetics and pharmacodynamics after single and repeated daily doses.

The relationship between indenolol (an investigational agent) plasma levels and the drug's effect on blood pressure and heart rate was investigated after single and repeated once daily administration at two dosage levels (60 mg and 120 mg) in two different groups of patients with first or second stage hypertension, according to the World Health Organization classification. The pharmacokinetic data were indicative of a first order absorption-elimination curve; time of maximum plasma levels was 1.5 to two hours, and elimination half-life was four hours.