Anti-asthmatic activity of BB-1502 by inhalation.

The anti-asthmatic activity, pulmonary mechanics and cardiovascular effects of BB-1502 (9-cyclohexyl-2-n-propoxy-9H-adenine) administered by aerosol were evaluated in guinea pigs and dogs and compared with the effects of salbutamol. BB-1502 protected guinea pigs from allergic asthma induced by aerosolized egg albumin antigen. The potency of BB-1502 was approx. 1/7 that of salbutamol when the test drugs and antigen were aerosolized simultaneously, whereas the two drugs were equipotent when administered 60 min prior to the antigen challenge. The duration of the anti-asthmatic action of BB-1502 appeared to be much longer than that of salbutamol. In dogs, BB-1502 and salbutamol showed comparable activity in preventing ascaris antigen-induced asthmatic symptoms. Disodium cromoglycate showed anti-asthmatic activity at high doses while aminophylline was inactive by inhalation. No cardiopulmonary side effects were observed in guinea pigs or dogs following the inhalation of BB-1502. The doses were 800-5,000 times higher than those needed to produce the anti-asthmatic activity. Salbutamol caused significant tachycardia, hypotension and tachypnea at doses 100-300 times its anti-asthmatic dose.