The exact relationship between dopamine and erection is very complex. Experiments have confirmed that dopamine plays an important role in the initiation of sexual stimulation in rats, which indicates that the treatment of impotence with dopaminergic drugs may act on the central control site of erection.
Apomorphine is a dopamine D2 receptor agonist acting on the paraventricular nucleus and supraoptic nucleus of the hypothalamus. Its chemical structure is similar to morphine, but it has no anesthetic effect and addiction. It can increase the content of dopamine in the brain, enhance sexual desire and induce penis erection. At present, it is believed that apomorphine induces erections by expanding the cavernous artery of the penis through the sacral parasympathetic plexus. Apomorphine is almost effective for patients with different degrees of impotence. Oral or subcutaneous injection of 70% of apomorphine can induce erection within 20 minutes, and the curative effect is positive. At the same time, more than 90% of patients can maintain their desire for 18 months after taking apomorphine, indicating that apomorphine has the advantages of rapid onset, spontaneity and predictability. The main adverse reactions are nausea, vomiting, sweating, lethargy and dizziness, but they only occur at high doses. Their side effects are small, and the curative effect is good, which has a potential market.
Bromocriptine is an oral dopaminergic receptor activator, which acts on the pituitary and can inhibit the secretion of prolactin. Bromocriptine has a narrow scope of application in the treatment of impotence. It is only used for erectile dysfunction in patients with hyperprolactinemia and maintenance hemodialysis. It is not used routinely in clinical practice. The treatment condition is that the patient's serum testosterone should be within the normal range. Because of its many side effects, such as nausea, vomiting, headache, dizziness, and occasional hypotension, the use of this drug is limited.