VA Class:CV701
Methyclothiazide is a thiazide diuretic and antihypertensive agent.
Methyclothiazide is administered orally.
Dosage of methyclothiazide should be individualized according to the patient's requirements and response. If methyclothiazide is added to a regimen of a patient stabilized on a potent hypotensive agent, the dosage of the hypotensive agent should initially be reduced to avoid the possibility of severe hypotension.
For the management of edema, the usual initial adult dosage of methyclothiazide is 2.5-10 mg daily in a single dose in the morning. The maximum effective single dose is 10 mg, and this dose should not be exceeded. In edematous patients, a maintenance dosage of 2.5-5 mg daily in a single dose is usually adequate after several days or when nonedematous weight is attained.
For the management of hypertension, the manufacturer recommends a methyclothiazide dosage of 2.5-5 mg once daily in adults.600 Dosages exceeding 5 mg once daily usually will not result in additional blood pressure reduction.600
Monitoring and Blood Pressure Treatment Goals
The patient's renal function and electrolytes should be assessed 2-4 weeks after initiation of diuretic therapy.1200 Blood pressure should be monitored regularly (i.e., monthly) during therapy and dosage of the antihypertensive drug adjusted until blood pressure is controlled.1200 The manufacturer states that if an adequate blood pressure response is not achieved within 8-12 weeks with a methyclothiazide dosage of 5 mg daily, another antihypertensive agent should be added;600 some experts state that the second antihypertensive agent should be one with demonstrated benefit and preferably with a complementary mechanism of action (e.g., angiotensin-converting enzyme [ACE] inhibitor, angiotensin II receptor antagonist, calcium-channel blocker).1200 If goal blood pressure is still not achieved, a third drug may be added.1200 (See Uses: Hypertension in Adults, in the Thiazides General Statement 40:28.20.) In patients who develop unacceptable adverse effects, the drug should be discontinued and another antihypertensive agent from a different pharmacologic class should be initiated.1200, 1216
The goal of hypertension management and prevention is to achieve and maintain optimal control of blood pressure.1200 However, the optimum blood pressure threshold for initiating antihypertensive drug therapy and specific treatment goals remain controversial.1201, 1207, 1209, 1222 A 2017 multidisciplinary hypertension guideline from the American College of Cardiology (ACC), American Heart Association (AHA), and a number of other professional organizations generally recommends a blood pressure goal of less than 130/80 mm Hg in all adults, regardless of comorbidities or atherosclerotic cardiovascular disease (ASCVD) risk.1200 Many patients will require at least 2 drugs from different pharmacologic classes to achieve this blood pressure goal; the potential benefits of hypertension management and drug cost, adverse effects, and risks associated with the use of multiple antihypertensive drugs also should be considered when deciding a patient's blood pressure treatment goal.1200, 1220
For additional information on target levels of blood pressure and on monitoring therapy in the management of hypertension, see Blood Pressure Monitoring and Treatment Goals under Dosage: Hypertension, in Dosage and Administration in the Thiazides General Statement 40:28.20.
Methyclothiazide shares the pharmacologic actions, uses, and toxic potentials of the thiazides, and the usual precautions of thiazide administration should be observed. (See Cautions in the Thiazides General Statement 40:28.20.)
Methyclothiazide is absorbed from the GI tract. Little information is available on the extent of absorption and the distribution of methyclothiazide in the body. Methyclothiazide is excreted unchanged in urine.
Methyclothiazide is a thiazide diuretic. Methyclothiazide occurs as a white or practically white, crystalline powder and may have a slight odor. The drug is very slightly soluble in water and slightly soluble in alcohol and has a pKa of 9.4.
Commercially available methyclothiazide tablets have an expiration date of 5 years following the date of manufacture.
For further information on chemistry and stability, pharmacology, pharmacokinetics, uses, cautions, acute toxicity, drug interactions, laboratory test interferences, and dosage and administration of methyclothiazide, see the Thiazides General Statement 40:28.20.
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
Oral | Tablets | 5 mg* | Methyclothiazide Tablets |
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
AHFS® Drug Information. © Copyright, 1959-2022, Selected Revisions January 21, 2019. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, MD 20814.
Only references cited for selected revisions after 1984 are available electronically.
104. Appel LJ. The verdict from ALLHAT—thiazide diuretics are the preferred initial therapy for hypertension. JAMA . 2002; 288:3039-42. [PubMed 12479770]
105. The ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). JAMA . 2002; 288:2981-97. [PubMed 12479763]
106. Izzo JL, Levy D, Black HR. Importance of systolic blood pressure in older Americans. Hypertension . 2000; 35:1021-4. [PubMed 10818056]
107. Frohlich ED. Recognition of systolic hypertension for hypertension. Hypertension . 2000; 35:1019-20. [PubMed 10818055]
108. Bakris GL, Williams M, Dworkin L et al. Preserving renal function in adults with hypertension and diabetes: a consensus approach. Am J Kidney Dis . 2000; 36:646-61. [PubMed 10977801]
1200. Whelton PK, Carey RM, Aronow WS et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol . 2017; [PubMed 29146535]
1201. Bakris G, Sorrentino M. Redefining hypertension - assessing the new blood-pressure guidelines. N Engl J Med . 2018; 378:497-499. [PubMed 29341841]
1207. Burnier M, Oparil S, Narkiewicz K et al. New 2017 American Heart Association and American College of Cardiology guideline for hypertension in the adults: major paradigm shifts, but will they help to fight against the hypertension disease burden?. Blood Press . 2018; 27:62-65. [PubMed 29447001]
1209. Qaseem A, Wilt TJ, Rich R et al. Pharmacologic treatment of hypertension in adults aged 60 years or older to higher versus lower blood pressure targets: a clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians. Ann Intern Med . 2017; 166:430-437. [PubMed 28135725]
1216. Taler SJ. Initial treatment of hypertension. N Engl J Med . 2018; 378:636-644. [PubMed 29443671]
1220. Cifu AS, Davis AM. Prevention, detection, evaluation, and management of high blood pressure in adults. JAMA . 2017; 318:2132-2134. [PubMed 29159416]
1222. Bell KJL, Doust J, Glasziou P. Incremental benefits and harms of the 2017 American College of Cardiology/American Heart Association high blood pressure guideline. JAMA Intern Med . 2018; 178:755-7. [PubMed 29710197]
600. Mylan Pharmaceuticals. Methyclothiazide tablets prescribing information. Morgantown, WV; 2012 Apr.