title: Risedronate gastrointestinal absorption is independent of site and rate of administration.
abstract: OBJECTIVE
  Two studies were conducted to compare the absorption of risedronate administered as a solution to three different gastrointestinal sites (study A) and to determine the extent of absorption of risedronate solution administered by rapid and slow infusion to the second part of the duodenum (study B).
  
  
  METHODS
  Each study was designed as a single-dose, crossover (three periods, study A; two periods, study B) trial in healthy male subjects, with a 14-day washout period between dosing. Subjects fasted overnight before drug administration and for 4 hours after drug administration. In study A, a risedronate solution of 40 mg in 30 mL of water was administered directly into the stomach, the second part of the duodenum, or the terminal ileum over 1 minute via a nasoenteral tube in a three-period crossover design. In study B, a risedronate solution of 40 mg in 30 mL of water was administered directly into the second part of the duodenum over 1 minute and over 1 hour in a randomized, two-period crossover design. Serum and urine samples were obtained for 48 hours after dosing for risedronate analysis.
  
  
  RESULTS
  Eight subjects completed each study. No statistically significant site-specific differences in any pharmacokinetic parameter were observed (study A). Based on the area under the serum concentration-time profile and the amount of drug excreted in the urine unchanged, the extent of risedronate absorption did not differ significantly following a rapid or a slow infusion (study B). Only minor symptomatic complaints were reported by subjects, such as headaches and body aches.
  
  
  CONCLUSIONS
  These studies indicate that the rate and extent of risedronate absorption are independent of the site of administration along the gastrointestinal tract, and that the extent of absorption is not affected by the rate of administration.
authors.affiliation: Clinical Pharmacology & Pharmacokinetics Department, Procter & Gamble Pharmaceuticals, Cincinnati, Ohio 45242-1434, USA. mitchell.dy@pg.com
authors.forename: D Y
authors.initials: DY
authors.lastname: Mitchell
authors.forename: R A
authors.initials: RA
authors.lastname: Eusebio
authors.forename: L E
authors.initials: LE
authors.lastname: Dunlap
authors.forename: K A
authors.initials: KA
authors.lastname: Pallone
authors.forename: J D
authors.initials: JD
authors.lastname: Nesbitt
authors.forename: D A
authors.initials: DA
authors.lastname: Russell
authors.forename: M E
authors.initials: ME
authors.lastname: Clay
authors.forename: P J
authors.initials: PJ
authors.lastname: Bekker
mesh_terms: D019540:Area Under Curve; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*; D004304:Dosage Forms; D004386:Duodenum / Q000378:metabolism; D012968:Etidronic Acid / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D005753:Gastric Mucosa / Q000378:metabolism; D006801:Humans; D007082:Ileum / Q000378:metabolism; D007408:Intestinal Absorption; D008297:Male; D000068296:Risedronic Acid
chemical_list: D002121:Calcium Channel Blockers; D004304:Dosage Forms; D000068296:Risedronic Acid; D012968:Etidronic Acid