What is the dosage for captopril and hydrochlorothiazide?

The starting dose is 25/15 mg once daily. The dose may be increased every 6 weeks.

Which drugs or supplements interact with captopril and hydrochlorothiazide?

Captopril may increase potassium levels (hyperkalemia) in blood. Therefore, there is an increased risk of hyperkalemia when captopril is given with potassium supplements or drugs that increase potassium levels (for example, spironolactone [Aldactone]).

There have been reports of increased lithium (Eskalith, Lithobid) levels when lithium is used in combination with ACE inhibitors. The reason for this interaction is not known, but the increased levels may lead to toxicity from lithium.

There have been reports that aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Children’s Advil/Motrin, Medipren, Motrin, Nuprin, PediaCare Fever, etc.), indomethacin (Indocin, Indocin-SR), and naproxen (Anaprox, Naprelan, Naprosyn, Aleve) may reduce the effects of ACE inhibitors.

Combining captopril or other ACE inhibitors with nonsteroidal anti-inflammatory drugs (NSAIDs) in patients who are elderly, volume-depleted (including those on diuretic therapy), or with poor kidney function may result in reduced kidney function, including kidney failure. These effects usually are reversible.

Nitritoid reactions (symptoms include facial flushing, nausea, vomiting and hypotension or low blood pressure) may occur when injectable gold (sodium aurothiomalate), used in the treatment of rheumatoid arthritis, is combined with ACE inhibitors, including captopril. 

Hydrochlorothiazide reduces the elimination of lithium (Lithobid) by the kidneys and can lead to lithium toxicity. Nonsteroidal antiinflammatory drugs, for example, ibuprofen, may reduce the blood pressure lowering effects of hydrochlorothiazide. Blood sugar levels can be elevated by HCTZ, necessitating adjustment in the doses of medications that are used for treating diabetes. Combining HCTZ with corticosteroids may increase the risk for low levels of blood potassium and other electrolytes. Low blood potassium can increase the toxicity of digoxin (Lanoxin). Cholestyramine (Questran, Questran Light) and colestipol (Colestid) bind to hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by 43%-85%.