Alteration of pharmacokinetics after halving a slow-release theophylline tablet

A study was carried out in 10 healthy volunteers to determine the effects on the bioavailability of theophylline from a biconvex-shaped, slow-release 400 mg theophylline tablet formulation when the tablet was taken whole or as two separate halves in a single dose. The subjects took one or other dosage regimen on different occasions separated by a 7-day washout period. The results showed that absorption was faster and plasma levels were higher when the 400 mg tablet was taken as 2 halves.