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The pharmacokinetics of single and combined doses of pentazocine HCl (40 and 80 mg) and tripelennamine HCl (50 and 100 mg) were studied in six healthy drug abusers. After intramuscular administration of 40 or 80 mg pentazocine alone, mean peak plasma concentrations at 15 minutes were 102 and 227 ng/ml, respectively, and mean plasma t½values were 4.6 and 5.3 hours, respectively. After intramuscular administration of 50 or 100 mg tripelennamine, mean plasma concentrations at 30 minutes were 105 and 194 ng/ml, respectively, and mean plasma t½values were 2.9 and 4.4 hours, respectively. After concurrent administration of pentazocine with tripelennamine, plasma pentazocine and tripelennamine concentrations at all time points were not significantly different from those when pentazocine or tripelennamine was administered alone. Coadministration of pentazocine and tripelennamine had no effect on the distribution, elimination, and clearance of either pentazocine or tripelennamine. In conclusion, there did not appear to be a clinically significant metabolic interaction between pentazocine and tripelennamine. Clinical Pharmacology and Therapeutics (1986) 39, 669–676; doi:10.1038/clpt.1986.117

The autoradiographic identification of chemically-induced, unscheduled DNA synthesis in primary cultures of adult rat hepatocytes is currently being validated as a predictive test for mutagens/carcinogens. Of 8 antihistaminic drugs tested, 2, pyrilamine maleate and tripelennamine HCl, were positive for unscheduled DNA synthesis. Further investigation of the mutagenic/carcinogenic potential of these compounds in alternate test systems is suggested.

INTRODUCTION Plimasin * is a new antiallergic preparation, combining 25 mg. of tripelennamine HCl (Pyribenzamine, Ciba) and 5 mg. of methyl-phenidylacetate (Ritalin, Ciba). The combination was originally used to determine whether it eliminated antihistaminic side-effects, such as drowsiness, which bother some patients. Preliminary European trials seemed to indicate that smaller doses of the antihistamine were effective when administered in Plimasin. This study is a preliminary evaluation of its effectiveness in skin conditions with special reference to its therapeutic indications. Methyl-phenidylacetate (methyl phenyl-2piperidineacetate hydrochloride), a new synthetic compound, has a marked psychomotor stimulating effect, similar to the effect known for some phenylisopropylamines. Subcutaneous injection of 1 to 2 mg/kg. in experimental animals stimulates respiration and increases motility considerably. Its clinical effect suggests in part amphetamine, but differs from it and must be classified between it and caffeine. STUDY This survey covers 193 successive cases