Captopril, sold under the brand name Capoten among others, is an angiotensin-converting enzyme (ACE) inhibitor used for the treatment of hypertension and some types of congestive heart failure. Captopril was the first oral ACE inhibitor found for the treatment of hypertension. It does not cause fatigue as associated with beta-blockers. Due to the adverse drug event of causing hyperkalemia, as seen with most ACE Inhibitors, the medication is usually paired with a diuretic. Captopril was patented in 1976 and approved for medical use in 1980. Structure–activity relationship
Captopril has an L-proline group which allows for it to be more bioavailable within oral formulations. The thiol moiety within the molecule has been associated with two significance adverse effects: the hapten or immune response. This immune response, also known as agranulocytosis, can explain the adverse drug events which may be seen in captopril with the allergic response, which would be: hives, severe stomach pain, difficulty breathing, swelling of the face, lips, tongue or throat.In terms of interaction with the enzyme, the molecules thiol moiety will attach to the binding site of the ACE enzyme. This will inhibit the port at which the angiotensin-1 molecule would normally bind, therefore inhibiting the downstream effects within the renin-angiotensin system. Medical uses
Captoprils main uses are based on its vasodilation and inhibition of some renal function activities. These benefits are most clearly seen in:

Hypertension
Cardiac conditions such as congestive heart failure and after myocardial infarction
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 one study has been negative. Formal clinical trials in depressed patients have not been reported.It has also been investigated for use in the treatment of cancer. Captopril stereoisomers were also reported to inhibit some metallo-β-lactamases. Adverse effects
Adverse effects of captopril include cough due to increase in the plasma levels of bradykinin, angioedema, agranulocytosis, proteinuria, hyperkalemia, taste alteration, teratogenicity, postural hypotension, acute renal failure, and leukopenia. Except for postural hypotension, which occurs due to the short and fast mode of action of captopril, most of the side effects mentioned are common for all ACE inhibitors. Among these, cough is the most common adverse effect. Hyperkalemia can occur, especially if used with other drugs which elevate potassium level in blood, such as potassium-sparing diuretics. Other side effects are:

Itching
Headache
Tachycardia
Chest pain
Palpitations
Dysgeusia
WeaknessThe adverse drug reaction (ADR) profile of captopril is similar to other ACE inhibitors, with cough being the most common ADR. However, captopril is also commonly associated with rash and taste disturbances (metallic or loss of taste), which are attributed to the unique thiol moiety. Overdose
ACE inhibitor overdose can be treated with naloxone. History
In the late 1960s, John Vane of the Royal College of Surgeons of England was working on mechanisms by which the body regulates blood pressure. He was joined by Sérgio Henrique Ferreira of Brazil, who had been studying the venom of a Brazilian pit viper, the jararaca (Bothrops jararaca), and brought a sample of the vipers venom.