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Nasal absorption of procyc1idine, a synthetic anticholinergic compourd, was investigated in Wistar rats and Beagle dogs. The dosing solution was Prepared by dissolving 14< /sup>C-procyclidine in 50% ethanolic saline. The dosing Solution was administered intravenously and intranasally to rats at dose of 0.6mg/kg(I.e., 60mcl/kg in the form of a 1% w/v solution), and intravenously orally and intranasally to dogs at a dose of 0.3mg/kg (I.e.,6mcl/kg in the form of a 5% w/v solution). Blood samples were taken from an arfery of the animals through the catheter for periods of 1200 (thor rats) aud 1440 min (for dogs), and the radioactiviy in the samples was determined by liquld scintillation counting. The nasal bioavailabilitivity of procyclldine in rats and dogs, based on the radioactivity was calculated to be 81.1 and 98.6%, respectively. In both rats and dogs, the plasma profiles oi procyclidlne following nasal admin istratlon were very close to those following intravenous administration, leading to nearly superlmposable profiles between the two Protocols. In dogs, nasal administration resulted in significantly higher plasma concentrations during the first 30 min period compared to oral administration, suggesting the superiority of the nasal route over the oral route in terms of a prompt expression of the phaymacologyical effect of the drug. The result obtained in this study indicate that procyclldine is rapidly and nearly completely absorbed via the nasal route. If conclusion, nasal administration represents a viable alternative to intravenous administration in the case of procyclidine.
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