Captopril (rINN) is an angiotensin-converting enzyme inhibitor  used for the treatment of hypertension and some types of congestive heart failure. Captopril was the first ACE inhibitor developed and was considered a breakthrough both because of its novel mechanism of action and also because of the revolutionary development process. Captopril is commonly marketed by Bristol-Myers Squibb under the trade name Capoten.

Captopril was developed in 1975 by three researchers at the U.S. drug company Squibb : Miguel Ondetti, Bernard Rubin and David Cushman. Squibb filed for U.S. patent protection on the drug in February 1976 and U.S. Patent 4,046,889 was granted in September 1977.
The development of captopril was amongst the earliest successes of the revolutionary concept of structure-based drug design. The renin-angiontensin-aldosterone system had been extensively studied in the mid-20th century and it had been decided that this system presented several opportune targets in the development of novel treatments for hypertension. The first two targets that were attempted were renin and ACE. Captopril was the culmination of efforts by Squibb's laboratories to develop an ACE inhibitor.
Ondetti, Cushman and colleagues built on work that had been done in the 1960s by a team of researchers led by John Vane at the Royal College of Surgeons of England. The first breakthrough was made by Kevin K.F.Ng in 1967 when he found that the conversion of angiotensin I to angiotensin II took place in the pulmonary circulation instead of in the plasma. In contrast, Sergio Ferreira found that bradykinin disappeared in its passage through the pulmonary circulation. The conversion of angiotensin I to angiotensin II and the inactivation of bradykinin was thought to be mediated by the same enzyme.

In 1970, using bradykinin potentiating factor provided by Sergio Ferreira, Ng and Vane found that the conversion of angiotensin I to angiotensin II was inhibited during its passage through the pulmonary circulation. BPF was later found to be a peptide in the pit viper  venom which was a “collected-product inhibitor” of the converting enzyme. Captopril was developed from this peptide after it was found via QSAR-based modification that the terminal sulfhydryl moiety of the peptide provided a high potency of ACE inhibition.
Captopril gained FDA approval in June 1981. The drug went generic in the U.S. in February 1996 as a result of the end of market exclusivity for Bristol-Myers Squibb.
 

1) Hypertension
2) Cardiac conditions such as post myocardial infarction and congestive heart failure
3) Preservation of kidney function in diabetic nephropathy
Additionally, it has shown mood-elevating properties in some patients. This is consistent with the observation that animal screening models indicate putative antidepressant activity for this compound, although there has been one negative study. Formal clinical trials in depressed patients have not been reported.
It has also been investigated for use in the treatment of cancer.

Formula :C₉H₁₅NO₃S 
Mol. mass: 217.29
Bioavailability :70–75%
Metabolism: hepatic
Half life: 1.9 hours
Excretion :renal