Amrinone is a drug that was used to treat severe heart failure that did not respond to other medications. It is now discontinued both in Germany and most other German-speaking countries, partly because of its frequent side effects, and has been replaced by more effective agents.
What is amrinone?
Amrinon is no longer offered in Germany as well as most other German-speaking countries in the meantime also due to the frequent side effects and was replaced by more effective means. Chemically, amrinone is an inhibitor that interferes with phosphodiesterase. In the body, it prevents the breakdown of cyclic adenosine monophosphate, which is a signaling substance in the areas of metabolism and hormone action. It was used during the availability of the drug mainly as an acute drug for heart failure, because it often causes a rapid reduction in blood pressure.
Pharmacological action
After administration of amrinone, the drug acts on two organs in particular. The heart muscle is provided with an increased supply of calcium ions, so that the strength of the contractions of the heart muscle is increased. This is achieved in the medical sense by a release of larger amounts of cyclic adenosine monophosphate. Furthermore, amrinone acts on the blood vessels. The mentioned concentration of calcium ions decreases in the so-called smooth muscle cells of the blood vessels. As a result, the state of tension (tone) within the vessel walls decreases, causing blood pressure to decrease as a result of the drug. The effects on the heart muscle and blood vessels together produce a clearly measurable and noticeable decrease in blood pressure in the patient’s body. However, the effects of amrinone can also have a negative impact, so the contraindications of the drug include severe cardiac arrhythmias, which must be treated separately by antiarrhythmic drugs. Severe renal insufficiency is also among the contraindications, as well as pregnancy during the administration of amrinone is not advisable. It should therefore be replaced by another agent if the drug must be taken for a prolonged period.
Medicinal use and application
Amrinone is administered either as an injection or in tablet form; both variants were common during the availability of the drug. The normal administration form comes in ampoules of 20 milliliters each. Amrinone is used exclusively for the treatment of the aforementioned heart failure; there are no other off-label uses. It is generally a short-term drug that can produce a rapid effect and is also very rarely administered long-term due to the frequent side effects. The simultaneous administration of dobutamine can enhance the effect of PDE-5 inhibitors. Various studies attest the drug an average effect, among doctors the drug is not uncontroversial. In a smaller study with 15 patients, no effect on the contractility of the heart muscle was detected in two-thirds of the test candidates, although this should be one of the main areas of application of Amrinon. None of the studies conducted reported any long-term benefits caused by amrinone. However, it is suitable as a drug to be administered to patients who do not respond to known preparations (such as digitalis or certain ACE inhibitors). Another use case is during heart-lung transplantation, but here, too, medicine has now found more effective drugs.
Risks and side effects
Amrinone may cause various gastrointestinal symptoms, which include (usually together) nausea and, as a consequence, vomiting. Furthermore, amrinone may cause mild abdominal pain and also irritation of the sense of taste. Rare side effects include fever and possible swelling of the spleen. The liver may be disturbed in its functioning. Amrinone also has the decrease of blood pressure as a goal, but at the same time too high a drop in blood pressure is an undesirable side effect of the drug. The heart may also be affected by tachycardia and persistent ventricular fibrillation, in these cases immediate notification of the doctor is necessary.Myalgias, pain originating from certain muscles, are also among the very rare side effects of Amrinon. Decrease in platelets in the blood has also been observed, but it can be reversed.