Table 2.

Pharmacokinetic properties of hydrochlorothiazide

Pharmacokinetics	Effect	References
Bioavailability	Oral administration of the drug ranges from 25 to 75 mg/day, and has a bioavailability of 60–80%.	[34, 35]
Absorption	Gastrointestinal absorption of the drug is rapid and peak plasma concentration is achieved at ~ 2 h. With the majority of the drug is absorbed in the duodenum and the upper jejunum.	[34, 36]
Distribution	The drug is transported ~ 40% bound to plasma proteins and it can also accumulate in erythrocytes. The ratio between the drug in erythrocytes and plasma averages 3.5. Another report showed the concentration of the drug in erythrocytes could be as high nine-fold to that of plasma.	[36, 37]
Metabolism	Limited evidence exists related to the metabolism of this drug. However, 2-amino-4-chloro-1,3-benzenedisulfonamide and chlorothiazide are some of the metabolites that have been detected in urine after administration of this drug.	[36–39]
Elimination	The half-life of HCTZ is estimated to be 5 to 14 h. The main excretion route for this drug is the kidneys, with the mean renal clearance of ~ 300 mL/min and greater than 95% of the absorbed drug shown to be excreted unchanged in urine.	[33, 36]