Nicotine carbomer enemas - pharmacokinetics of a revised formulation

Green, John, Rhodes, J., Thomas, Gareth A. O., Evans, B. K., Feyerabend, C., Russell, M. A. H. and Sandborn, W. J. 1998. Nicotine carbomer enemas - pharmacokinetics of a revised formulation. Italian Journal of Gastroenterology and Hepatology 30 (3) , pp. 260-265.

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Abstract

Abstract: AIMS Ulcerative colitis is predominantly a disease of non-smokers, and transdermal nicotine has therapeutic benefit but causes frequent side-effects. We have previously developed a topical enema combining nicotine with a polyacrylic carbomer; pharmacokinetic parameters were similar in healthy volunteers and patients with active ulcerative colitis. This enema was reformulated to reduce and delay nicotine absorption, thereby improving tolerance. METHOD Pharmacokinetic observations and side-effects with both formulations are compared in the same 8 healthy volunteers--all non-smokers, 3 male, mean age 33 years. Six milligrams of nicotine were complexed with 400 mg of carbomer in a 100 ml liquid enema. The original formulation was buffered with potassium/phosphate to pH 5.5, kinematic viscosity was 3 mNm; the revised preparation incorporated trometamol 1% solution to buffer to pH 4.2, viscosity 5 mNm. All subjects had the two formulations on separate occasions at least a month apart, with serial blood measurements and side-effect profile recorded for 8 hours. RESULTS The revised enema formulation significantly reduced Cmax for nicotine from 8.3 +/- 2.7 to 6.6 +/- 2.1, p = 0.03 with some reduction in nicotine absorption and improved tolerance. Although there was considerable intersubject variation in profiles for nicotine and cotinine, they were similar for each subject on both occasions. CONCLUSIONS The lower pH and greater viscosity reduced the amount of free nicotine in its unionised form available for absorption, but made it possible to expose colonic mucosa to the same nicotine dose. In other drug formulations where side-effects are a limiting factor these modifications may also be relevant.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Medicine
ISSN:	1125-8055
Last Modified:	11 Aug 2026 11:00
URI:	https://orca.cardiff.ac.uk/id/eprint/188882

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