Papaverine belongs to the active substance group of vasodilatative antispasmodics. As a cAMP phosphodiesterase inhibitor (PDE inhibitor), it has an antispasmodic effect on smooth muscles.
Papaverine is a natural compound found in the milky sap of opium poppies. The active ingredient is mainly used in heart surgery. Papaverine prevents blood vessel spasms when removing arteries, which is required for bypass operations, for example. It also promotes arterial blood flow to erectile tissue in the penis. For this purpose, papaverine is injected directly into the erectile dysfunction as a so-called “cavernous body auto-injection therapy.”
Mechanism of Action
Papaverine belongs to the active substance group of vasodilatative antispasmodics. As a cAMP phosphodiesterase inhibitor (PDE inhibitor), it has an antispasmodic effect on smooth muscles. Phosphodiesterases (PDE) are enzymes that split so-called “second messengers” and thus render them ineffective. These messenger substances include cAMP and cGMP neurotransmitters, which are responsible for transmitting external changes (stimuli) into the cell interior. By inhibiting the PDE, signal transmission is promoted and the effect of a particular stimulus can be enhanced.
There are three different types of PDE inhibitors:
- PDE3: increases the heart’s ability to beat and dilates blood vessels in the body.
- PDE4: suppresses numerous endogenous pro-inflammatory substances.
- PDE5: promotes signal transmission during sexual arousal and ensures higher blood flow to the penis.
It is very likely that papaverine also inhibits transmembrane calcium influx. This supports the relaxation of the smooth muscles and increases the blood flow in the corresponding vessels.
Side effects of papaverine are rare when taken as directed. Severe drops in blood pressure, cardiac arrhythmias, or increases in intracranial pressure are rare. Hemiplegia, epileptic seizures, blurred vision, and reduced consciousness are other serious side effects of papaverine. Mild papaverine side effects include fatigue, dizziness, gastrointestinal upset, skin rashes, and excessive sweating.
Papaverine injections for erectile dysfunction come with a high risk of serious side effects that require immediate medical attention. These side effects include permanent erections (priapism), severe allergic reactions with hives (urticaria), cardiac arrhythmia, or liver damage.
The benefit of papaverine is undisputed, especially when used in bypass therapy or coronary revascularization. However, it is increasingly regarded as a second-line drug. Propiverine has now established itself for vasodilatation during these interventions.
Active Ingredient Information
Molar mass: 339.38 g mol-1
Mean half-life: approx. 1.8 h
Q0 value: 1.0
Child fabric(s): papaverine hydrochloride