Understanding Apomorphine and Its Emerging Role in Sexual Function

Apomorphine is a medication typically used for treating “off” episodes of Parkinson’s disease. It works by activating dopamine receptors in the brain, helping to replace or mimic the effects of natural dopamine. Since dopamine plays a role in sexual arousal, apomorphine could potentially influence one’s desire and libido, as well as help with stimulating erections.

This medication used to be approved by the U.S. Food and Drug Administration (FDA) for use with erectile dysfunction treatment (ED), but has since only been approved for use with Parkinson’s. However, recent clinical trials have sparked interest in reconsidering the drug for ED.

Does Apomorphine Work?

Between 2000-now, studies have shown small-dose (2-4 mg) apomorphine tablets placed under the tongue (sublingually) or doses administered by injection can be effective at helping with successful erections within 20 minutes for around half of the men studied. This is considerably faster than traditional PDE5 inhibitors such as Viagra or Cialis, which typically take around an hour to be effective. There has also been at least one study about a nasal spray version, but this proved to be less effective.

Research has also explored apomorphine’s effects beyond erectile function. In female patients experiencing hyposexual desire disorder (HSDD), which causes low levels of sexual desire, apomorphine appeared to help improve symptoms. This effect is thought to be related to dopamine stimulation in the brain, which is known to influence motivation and sexual interest. Interestingly, this likely links to the warnings found on Parkinson’s disease-related drugs detailing certain impulse control issues associated. According to this study, there were the same side-effects for women as there were for men.

Nevertheless, there has been very limited evidence to support an increase in libido or desire in male patients. While dopamine stimulation may influence impulse control, the mechanism may be ineffective in some ED patients, which is consistent with many clinical trials.

Specifically, apomorphine may be less effective for men with diabetes, men who have had a radical prostatectomy (a surgery to treat prostate cancer by removing the prostate), or older men with heart problems.

How Safe is Apomorphine?

An older review of apomorphine for use with ED stated that it can be considered as a treatment when the “gold standard” (PDE5 inhibitors) treatments have not been working for the patient. 

Additionally, apomorphine may be offered for men being treated for cardiovascular issues, such as chest pain. This is because the nitrates in these heart medications do not interact well with traditional PDE5 inhibitors, and apomorphine has been proven to be safe with certain heart medications.

Side effects include:

• Dry mouth/irritation or skin tears near mouth
• Runny nose
• Chest tightness/fast heartbeat
• Dizziness, general weakness, or falling
• Fever, itchiness/hives, joint pain
• Redness or swelling near mouth
• Hoarse speech
• Trouble breathing or swallowing

Key Takeaways

• Apomorphine is traditionally used to treat Parkinson’s disease but has been used for erectile dysfunction in the past.
• Typically, it is taken as a tablet which dissolves under the tongue and has been provided as an injection or nasal spray.
• Though potentially less effective, apomorphine could be considered as a second option to PDE5 inhibitors like Viagra or Cialis. They should not be taken together.
• More research is needed to confirm if apomorphine should be prescribed for ED as well as Parkinson’s.

Resources

Altwein, J. E., & Keuler, F. U. (2001). Oral treatment of erectile dysfunction with apomorphine SL. Urologia Internationalis, 67(4), 257–263. https://doi.org/10.1159/000051001

Briganti, A., Chun, F. K., Salonia, A., Zanni, G., Deh??, F., Barbieri, L., Karakiewicz, P. I., Rigatti, P., & Montorsi, F. (2006). A comparative review of apomorphine formulations for erectile dysfunction. Drugs & Aging, 23(4), 309–319. https://doi.org/10.2165/00002512-200623040-00004

Caruso, S., Agnello, C., Intelisano, G., Farina, M., Di Mari, L., & Cianci, A. (2004). Placebo-controlled study on efficacy and safety of daily apomorphine SL intake in premenopausal women affected by hypoactive sexual desire disorder and sexual arousal disorder. Urology, 63(5), 955–959. https://doi.org/10.1016/j.urology.2003.12.018

Guillén, V., Rueda, J.-R., Lopez-Argumedo, M., Solà, I., & Ballesteros, J. (2020). Apomorphine for the treatment of erectile dysfunction: Systematic review and meta-analysis. Archives of Sexual Behavior, 49(8), 2963–2979. https://doi.org/10.1007/s10508-020-01817-5

Mohee, A., Bretsztajn, L., & Eardley, I. (2012). The evaluation of apomorphine for the treatment of erectile dysfunction. Expert Opinion on Drug Metabolism & Toxicology, 8(11), 1447–1453. https://doi.org/10.1517/17425255.2012.727797

Montorsi, F. (2002). The role of Apomorphine SL in the treatment of erectile dysfunction. European Urology Supplements, 1(3), 4–11. https://doi.org/10.1016/s1569-9056(02)00008-8

Mulhall, J. P., Bukofzer, S., Edmonds, A. L., & George, M. (2001). An open-label, uncontrolled dose-optimization study of sublingual apomorphine in erectile dysfunction. Clinical Therapeutics, 23(8), 1260–1271. https://doi.org/10.1016/s0149-2918(01)80105-3

 National Institutes of Health. (n.d.). DailyMed - apomorphine hydrocloride- apomorphine hydrochloride injection. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=aedf70e4-1949-44bc-bf1b-0f282c4f0705

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U.S. National Library of Medicine. (n.d.). Apomorphine sublingual: Medlineplus Drug Information. MedlinePlus. https://medlineplus.gov/druginfo/meds/a620044.html