Antidepressant drugs are extensively metabolized. Consequently, the biotransformation pattern of antidepressants has an important influence on their clinical properties, i.e., pharmacokinetics, toxicity, drug-drug interactions, side-effect profile and last but not least therapeutic efficacy. It was against this background that a multidisciplinary group of experts discussed the clinical relevance of the rapidly increasing body of knowledge of antidepressant-metabolizing enzymes. The variability of the response of a given individual to an antidepressant is determined genetically and by the environment. Genetic polymorphism of drug-metabolizing enzymes and inhibition by other substrates may affect the enzymatic biotransformation of antidepressants. In vitro assay techniques allow an estimation of the potential variability in clinical response to antidepressants and a reasonable prediction of the drug-drug interaction patterns. The results of in vitro tests should therefore be considered early in the development of an antidepressant as a background for designing clinical studies (treatment schedules and dosing). Physicians should have an understanding of the relevance of genetic polymorphism for clinical practice. Education is needed in order to fill the existing gaps in knowledge about antidepressant-enzyme interactions and their application in daily treatment practice. The information on potential drug interactions determined by genetic polymorphism and based on studies with enzymes should be increasingly contained in drug compendia.

Moclobemide is an effective and well-tolerated antidepressant for the treatment of elderly depressed patients.

In this double-blind study forty-seven patients with hay fever were treated for 8 days with either terfenadine 60 mg twice a day, astemizole 10 mg once a day or placebo. On the second day of treatment terfenadine was statistically significantly superior to astemizole and placebo according to the ratings of symptomatology, efficacy and individual symptoms. The median onset of symptom alleviation was 3 hours for terfenadine and 2 days for astemizole. On the eighth day both astemizole and terfenadine were statistically significantly more efficacious than placebo, but no significant differences were found between the two drugs. Both drugs were well tolerated.

The effects of terfenadine and pseudoephedrine, alone and in combination, have been assessed in a nasal provocation test and in perennial rhinitis. In a double-blind, placebo-controlled cross-over nasal provocation test, twelve men allergic to grass pollen were treated with two daily doses of placebo, terfenadine 60 mg, pseudoephedrine 120 mg, or the combination of the two, for 2 days preceding each test. The allergic reaction threshold, based on rhinorrhoea, sneezing and nasal inspiratory peak flow rate, was raised significantly both by terfenadine and pseudoephedrine, and their effects appeared additive (repeated measures analysis of variance). In a double-blind, randomized clinical study of perennial rhinitis two parallel groups, the efficacy and tolerability of terfenadine and terfenadine-pseudoephedrine were compared in 50 patients. Symptoms and signs in both groups were improved after 14 days of treatment. Differences between groups showed a trend in favour of terfenadine-pseudoephedrine, for swelling of the nasal mucosa (rhinoscopy) they were statistically significant. Both medications were well tolerated overall, although adverse events and reactions were more frequent in the terfenadine-pseudoephedrine group. In conclusion, terfenadine-pseudoephedrine and its constituents taken alone were effective. The combination performed better, but adverse events were somewhat more frequent with the combination than with terfenadine alone.

Eight healthy men received an oral dose of 0.25 mg/kg diazepam followed 40 min later by an intravenous infusion of 100 ml physiological sodium chloride solution, with or without 4.4 mg/kg theophylline. Psychomotor function was assessed after each blood sampling up to 5 h post-infusion. Thirty min after diazepam psychomotor performance measured by Card Sorting test and Digit Symbol Substitution test was impaired and subjects felt sleepy and could think less clearly (two factors of the Clyde Mood Scale). Theophylline antagonized the diazepam-induced impairment statistically significantly for up to 5 h and subjects felt less tense and less apprehensive (State Anxiety Inventory). Since pharmacokinetic parameters of diazepam seemed not to be different after theophylline, interaction at receptor level can be assumed.