Captopril dosage

Heart failure - Usual initial dosage is 25 mg 3 times daily. After 50 mg 3 times daily is reached, delay further dosage increases, where possible, for at least 2 weeks to determine if a satisfactory response occurs. Most patients have had a satisfactory clinical improvement at 50 or 100 mg 3 times daily. Do not exceed a daily dose of 450 mg. Captopril should generally be used in conjunction with a diuretic and digitalis. 

Because indomethacin may increase serum potassium concentrations, indomethacin and spironolactone should be administered concomitantly with caution. Potassium-sparing diuretics should be used with caution, and serum potassium should be determined frequently in patients receiving an angiotensin-converting enzyme (ACE) inhibitor (e.g., captopril). Concomitant administration with an ACE inhibitor may increase the risk of hyperkalemia. The dosage of spironolactone should be reduced, or the drug discontinued, as necessary. Patients with renal impairment may be at increased risk of hyperkalemia [65]. 

Numerous other ACE inhibitors have been synthesized and evaluated since captopril was announced in 1977. As of 1996, 16 were in use worldwide (157), all of which are variations of the designs exemplified in Table IX. Reviews are available that describe dosage, pharmacokinetics, metabolism, and routes of elimination of many of them (111,156-159). 

The doctor is sympathetic cough is sometimes a problem for patients taking captopril she prescribes an alpha-adrenoceptor (a-adrenoceptor) antagonist, prazosin, instead. Sam has problems initially with orthostatic hypotension however, after dosage reduction, prazosin is well tolerated and Sam s BP settles at 143/87 mmHg. 

Seta, Y. Higuchi, E. Otsuka, T. Kawahara, Y. Nishimura, K. Okada, R. Koike, H. Preparation and pharmacological evaluation of captopril sustained-release dosage forms using oily semisolid matrix. Int. J. Pharm. 1988, 41 (3), 255-262. 

There have been numerous reports of different rashes in association with ACE inhibitors. The most common skin reaction is a pruritic maculopapular eruption, which is reportedly more common with captopril (2-7%) than with enalapril (about 1.5%). This rash occurs in the usual dosage range and is more common in patients with renal insufficiency (70). Lichenoid reactions, bullous pemphigoid, exfoliative dermatitis, flushing and erythroderma, vasculitis/purpura, subcutaneous lupus erythematosus, and reversible alopecia have aU been reported (70-72). 

The end result of these differences, although apparent rather than real, may be why the recommended dose of captopril (an ACE Inhibitor, antihypertensive drug) is 75—450 mg per day in the United States and 37.5-122.5 mg per day in Japan (with overall adverse events of 39% and 3.8% respectively). With a nonsteroidal antiinflammatory agent, overall adverse events were 45-51 % in the United States and 24% in Japan at the same dosage however, efficacy was the same (Dziewanowska, 1992). In general, the British, Dutch and Scandinavian data are closer to those observed in the United States, with the German and Swiss data least reactive and French, Italian and Spanish in between. As mentioned previously, severe ADRs in clinical studies tend to be the same the major difference was in minor adverse events, such as nausea, headache and so on. Thus, national temperament also may play a part in the expectation of efficacy and ADR. This finding was reflected in a study of attitudes of 4000 nurses from 13 countries to ethnic tolerance of pain... 

Nahata, M.C. Morosco, R.S. Hippie, T.F. Stability of captopril in three liquid dosage forms. Am.J.Hosp.Pharm., 1994, 51, 95—96... 

Skin Rash ACE inhibitors occasionally cause a maculopapular rash that may be pruritic. The rash may resolve spontaneously or may respond to a reduced dosage or a brief course of antihistamines. Although initially attributed to the presence of the sulfhydryl group in captopril, a rash also may occur with other ACE inhibitors, albeit less frequently. 

The sulfhydryl group of captopril proved to be responsible not only for the excelleht ihhibitory activity of the compound but also for the two most common side effects, skin rashes and taste disturbances (e.g., metallic taste and loss of taste). These side effects usually subsided on dosage reduction or discontinuation of captopril. They were attributed to the presehce of the sulfhydryl group, because similar effects had beeh observed with penicillamine, a sulfhydryl containing agent used to treat Wilson s disease and rheumatoid arthritis (22,23). 

Low-dose aspirin (less than or equal to 100 mg daily) does not alter the antihypertensive efficacy of captopril and enalapril. No special precautions would therefore seem to be required with ACE inhibitors and these low doses of aspirin. A high dose of aspirin (2.4 g daily) has been reported to interact in 50% of patients in a single study. Aspirin 300 mg daily has been reported to interact in about 50% of patients in another study, whereas 325 mg daily did not interact in further study. Thus, at present, it appears that if an ACE inhibitor is used with aspirin in doses higher than 300 mg daily, blood pressure should be monitored more closely, and the ACE inhibitor dosage raised if necessary. Intermittent use of aspirin should be eonsidered as a possible cause of erratic control of blood pressure in patients on ACE inhibitors. 

---