Nicotine enemas for treatment of ulcerative colitis: a study of the pharmacokinetics and adverse events associated with three doses of nicotine.

BACKGROUND

Transdermal nicotine is of value in active ulcerative colitis but causes adverse events because of systemic absorption. Nicotine enemas may give rise to fewer adverse events.

AIM: To assess the pharmacokinetics of nicotine enemas in three doses.

METHODS

Thirteen volunteers, all non-smokers but three ex-smokers, were given enemas on separate occasions containing 3, 6 and 9 mg of nicotine, in ascending dose order. Adverse events were recorded and blood samples taken over 8 h for measurement of serum nicotine and cotinine.

RESULTS

Enemas were retained by most subjects. Eleven of 14 adverse events were 'early'--30-105 min after the enema, corresponding to maximum plasma nicotine concentrations; three events were later, 4-8 h after the enema and unrelated to the tmax. 'Early' adverse events occurred in eight subjects--six with 9 mg. The three highest plasma nicotine concentrations were with 9 mg and associated with headache, nausea and sweating. Only one had adverse events with 3 mg and withdrew from the study. Nicotine Cmax with 6 and 9 mg doses were respectively two and three times the value with 3 mg. Peak nicotine concentrations occurred 44-50 min after the enema.

CONCLUSION

The 6 mg dose of nicotine probably represents the dose to use in clinical practice - for the highest therapeutic dose with a low risk of adverse events.