THE POTENTIATING EFFECT OF ANTIHISTAMINIC DRUGS UPON THE SEDATIVE ACTION OF BARBITURATES

¹ Merck Institute for Therapeutic Research, Rahway, N. J.

The antihistaminic drugs Pyribenzamine, Neo-Antergan, Benadryl, and 3277 R.P. prolong the sleep-producing effects of Evipal in mice. This potentiating effect was observed when an antihistaminic drug 10 or 20 mgm./kgm. was injected subcutaneously, followed one-half hour later by Evipal 40 to 100 mgm./kgm. intraperitoneally.

All the mice receiving Evipal 100 mgm./kgm. went to sleep, and, on the average, 50 per cent of the animals awakened in about 37 minutes. The mean waking time was prolonged about 10 per cent by Pyribenzamine and Neo-Antergan, and about 40 per cent by Benadryl and 3277 R.P.

Comparable results were obtained by a combination of Benadryl and Nembutal in mice, and Benadryl and Evipal in guinea pigs.

These results appear to correlate with the reported incidence of sedation as a side effect in patients receiving antihistaminic drugs.