Pharmacokinetics of cisapride in horses after intravenous and rectal administration.
OBJECTIVE
To determine the i.v. pharmacokinetics of cisapride and measure systemic absorption after rectal administration.


METHODS
5 healthy adult mares (380 to 610 kg).


METHODS
Cisapride was administered, i.v., at a dosage of 0.1 mg/kg of body weight. In the same horses, after a 1-week washout period, cisapride was administered rectally at a dosage of 1 mg/kg by mixing crushed tablets with propylene glycol and administering the mixture into the rectum. After each drug administration, a series of blood samples were collected. Plasma was obtained and analyzed by high-performance liquid chromatography to determine cisapride concentration profiles after each drug administration.


RESULTS
After i.v. administration, peak plasma concentration was 221.4 ng/ml and harmonic mean half-life was 1.9 hours. Rectal absorption of cisapride was negligible. Cisapride was detected in plasma from only 3 of 5 horses for which mean systemic availability was 1.23%. Mean maximal plasma concentration after rectal administration of cisapride was 13.5 ng/ml.


CONCLUSIONS
After i.v. administration of cisapride, plasma concentration is high for approximately 2 hours. Cisapride mixed with propylene glycol and administered rectally at a dosage of 1 mg/kg is poorly and incompletely absorbed. Thus, cisapride is not clinically useful for rectal administration in horses.
Cook
G
G
Department of Food Animal and Equine Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA.
Papich
M G
MG
Roberts
M C
MC
Bowman
K F
KF
D000042:Absorption; D000285:Administration, Rectal; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002851:Chromatography, High Pressure Liquid / Q000379:methods / Q000662:veterinary; D020117:Cisapride; D005260:Female; D006736:Horses / Q000097:blood / Q000378:metabolism* / Q000502:physiology; D007275:Injections, Intravenous / Q000662:veterinary; D010277:Parasympathomimetics / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D010880:Piperidines / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019946:Propylene Glycol
D010277:Parasympathomimetics; D010880:Piperidines; D019946:Propylene Glycol; D020117:Cisapride