Effects of magnesium oxide on trichlormethiazide bioavailability

Area of Science:

• Pharmacokinetics
• Drug Interactions
• Gastroenterology

Background:

• Thiazide diuretics are commonly prescribed for hypertension.
• Antacids are frequently used to manage gastrointestinal discomfort.
• Understanding drug interactions is crucial for optimizing therapeutic outcomes.

Purpose of the Study:

• To investigate the effect of magnesium oxide (MgO) on the bioavailability of trichlormethiazide.
• To determine if MgO alters the extent or rate of trichlormethiazide absorption.

Main Methods:

• A randomized, two-way crossover study in 10 healthy subjects.
• Administration of trichlormethiazide alone and with MgO.
• Quantification of urinary trichlormethiazide excretion using HPLC.

Main Results:

• No significant difference in the overall 24-hour recovery or cumulative excretion of trichlormethiazide.
• MgO significantly increased the early excretion rate and absorption rate constant of trichlormethiazide.
• Solubility of trichlormethiazide increased with pH, but dissolution rate was unaffected in larger volumes.

Conclusions:

• Magnesium oxide does not impact the extent of trichlormethiazide bioavailability.
• MgO enhances the rate of trichlormethiazide absorption, potentially leading to faster onset of action.
• This interaction may be relevant for patients requiring rapid diuretic effects.