Influence of gastric pH changes on pharmacokinetic of a sustained-release formulation of theophylline.
The effect of magnesium-aluminum-hydroxide antacid (Maalox) on the oral absorption of theophylline anhydrous time-release capsules Somophyllin CRT was studied in eight healthy volunteers. The subjects were given 500 mg of theophylline alone or with 30 ml of antacid in a complete crossover design. Drug serum concentrations were determined by an immunoenzymatic method within 24 hours at frequent intervals. Antacid induced a significant reduction of theophylline serum levels and of the fraction absorbed at 1 and 1.5 hours of the monitoring period (less than 0.05), but no significant differences were found at later sampling time. Maalox did not influence the area under the curve from 0 to 24 hours and the peak concentrations; the time to peak was slightly but significantly longer with antacid (p less than 0.05). Our results indicate that physicochemical factors such as gastrointestinal fluid pH do not influence substantially absorption of the slow-release formulation Somophyllin.
Ferrari
M
M
Centro Ospedaliero Clinicizzato Valeggio s/M, University of Verona.
Olivieri
M
M
Romito
D
D
Biasin
C
C
Barozzi
E
E
Bassetti
S
S
D000328:Adult; D003692:Delayed-Action Preparations; D005744:Gastric Acid / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D013806:Theophylline / Q000008:administration & dosage / Q000493:pharmacokinetics*
D003692:Delayed-Action Preparations; D013806:Theophylline