Chlorothiazide / Methyldopa Dosage

Applies to the following strengths: 150 mg-250 mg; 250 mg-250 mg

Usual Adult Dose for:

Hypertension

Additional dosage information:

Renal Dose Adjustments
Liver Dose Adjustments
Dose Adjustments
Precautions
Dialysis
Other Comments

Usual Adult Dose for Hypertension

Initial dose: 1 tablet of (chlorothiazide-methyldopa 150 mg/250 mg) 2-3 times a day or
1 tablet of (chlorothiazide-methyldopa 250 mg/250 mg) 2-3 times a day.
Determine dosage by individual titration.
Maintenance dose: May increase to 4 tablets of (chlorothiazide-methyldopa 250 mg/250 mg)/day in divided doses.

Renal Dose Adjustments

Chlorothiazide is not recommended in patients with severe renal insufficiency since it is not expected to be filtered into the renal tubule (its site of action) when the glomerular filtration rate is less than 25 mL/min.

Liver Dose Adjustments

Methyldopa is not recommended in patients with liver cirrhosis or acute hepatitis, due to the risk of additional hepatotoxicity associated with methyldopa

Dose Adjustments

Methyldopa is largely excreted by the kidney, patients with impaired renal function may respond to smaller doses. Syncope in older patients may be related to an increased sensitivity and advanced arteriosclerotic vascular disease. This may be avoided by lower doses.

Precautions

Thiazides should be used with caution in severe renal disease and/or impaired hepatic function.

Dialysis

Methyldopa is slightly dialyzable (5% to 20%). Data regarding the disposition of chlorothiazide in patients undergoing hemodialysis is not available. Chlorothiazide is not efficacious in patients with end-stage renal disease as it is not secreted into the renal tubule (its site of action) in renal patients with failure.

Other Comments

If (chlorothiazide-methyldopa) does not adequately control blood pressure, additional doses of other agents may be given. When (chlorothiazide-methyldopa) is given with antihypertensives other than thiazides, the initial dosage of methyldopa should be limited to 500 mg daily in divided doses and the dose of these other agents may need to be adjusted to effect a smooth transition.