Effect of codeine on rat and guinea pig tracheal ciliary beat frequency

Codeine, the basic antitussive drug, has generally been thought to impair mucociliary function. Using the photodetection method the effect of codeine on mucociliary function was studied in rat after local and systemic administration and in guinea pig after systemic administration. In vitro rat tracheal ciliary beat frequency (CBF) was measured up to 40 min. There was 24.6 +/- 2.5% and 26.6 +/- 1.6% decrease in CBF after 1 mg/ml and after 10 mg/ml codeine solutions, respectively. In vivo codeine was administered in single i.v. doses of 10 and 15 mg/kg. No statistically significant differences were found in CBF responses, although there was a CBF decreasing tendency after the 15 mg/kg dose. The total follow-up time was 120 min. In guinea pig, 10 days s.c. codeine administration in daily doses of 3, 10 and 30 mg/kg had no effect on CBF. Although codeine was used in much higher concentrations than tissues concentrations after therapeutic doses of codeine, the effects on CBF were minimal. So it can be concluded that the generally accepted ciliostatic effect of codeine is overestimated.