COMPARATIVE PHARMACOKINETICS OF ORAL VERSUS SUBLINGUAL CLONIDINE

Study Objective: To compare the pharmacokinetic and pharmacodynamic pr ofile of orally versus sublingually administered clonidine. Design: Ra ndomized, crossover, nonblinded, open-label study. Setting: University tertiary-care center. Patients: 10 healthy male and female volunteers aged 20 to 42 years. Interventions: A heparinized catheter was placed intravenously for blood-sampling purposes. An automatic sphygmomanome ter was placed on the volunteers' left upper arm to obtain systolic an d diastolic blood pressure, and a pulse oximeter was placed on the rig ht index finger to measure heart rate (HR). Measurements and Main Resu lts: Serial blood samples were collected throughout the 24-hour study period to determine clonidine Concentrations. The effect of clonidine on blood pressure (BP) and HR also was measured. The half-life, area u nder the curve, maximum concentration, and time to reach maximum conce ntration were similar for both the sublingual and oral routes. BP and HR changes were similar for both sublingual and oral clonidine. Conclu sion: Both routes of administration resulted in similar pharmacokineti c and pharmacodynamic profiles. Attempts to shorten clonidine's latenc y with sublingual administration were unsuccessful. Our study shows th at a single dose of clonidine 0.3 mg has the same pharmacokinetic and dynamic profile when administered orally or sublingually. Therefore, t he sublingual route can be predictably used in fasting patients, those having difficulty swallowing or those who are unable to absorb drugs through the gastrointestinal tract; the sublingual dose is the same as the oral dose.