An experimental study on nasal absorption of gentamycin in dogs.

Drug absorptive function of the nasal mucosa has been a new and interesting subject of research in bridging rhinology and pharmacology. The authors applied a solution of gentamycin at a concentration of 40 mg/ml to 15 dogs at a dosage of 5 mg/kg for each through three routes of administration, ie, the intravenous, intramuscular and intranasal. The serum levels of gentamycin from 0 to 180 minutes after receiving the drug were determined with thin-layer scanning chromatographic method. It was found that if the bioavailability of the intravenous route was considered as 100%, the bioavailability of the intranasal route was 80.5%, and that of the intramuscular route was 42%. After giving drops of the drug into nasal cavity in above-mentioned dosage, the serum drug level reached a peak in 10 to 30 min ranging in 3.7 to 6.6 micrograms/ml. The half-life period of the drug given through this route was about three hours, indicating that the nasal mucosa is apt to be penetrated by gentamycin and allows the drug to be absorbed into the blood stream soon and maintained a long-acting level.