Parkinson’s disease is treated with an assortment of drugs that are dopamine agonists or increase dopamine levels in the brain. Although we are learning more about our neurotransmitters at a rapid rate, we are still often taken by surprise by side effects of these medications.

A friend of mine takes Mirapex, a dopamine agonist, which is fairly affective in controlling Parkinson’s symptoms, but when put into the marketplace odd side effects were reported. People on Mirapex (pramipexole) were experiencing various “impulse control disorders.” You may have seen reports of folks that gambled away their savings, their cars, even their homes. I recall one report of a priest that used church collection money to gamble in Atlantic City. I asked my friend if he had any of these gambling urges and he said no, but did admit to a new love for internet shopping.

This class of drug has been associated with side effects like gambling, shopping, eating, hyper-sexuality, and other impulse control issues. These are in addition to the more commonly noted dizziness, drowsiness, edema, and cognitive problems.

Another Parkinson’s drug recently made the news when a 42-year-old woman checked herself into a Turkish hospital with a chief complaint of random, uncontrolled orgasms. She had started taking rasagiline, Azilect in the US, seven days earlier and began experiencing hyper-arousal, increased libido, and then orgasms that occurred 3 to 5 times a day and lasted about 20 seconds. There are previous reports of spontaneous ejaculation in a man that was taking rasagiline. Both patients returned to normal after discontinuing the medication. The Turkish woman opted to resume treatment after 15 days and her symptoms returned. Her case study is slated to appear in the journal Parkinsonism and Related Disorders.

Dopamine is a well known neurotransmitter associated with pleasure. It is strongly associated with addictive behaviors from tobacco smoking to heroin addiction. It has different effects depending on what area of the brain it is in, from alertness and motivation to lust and milk production. I think it is important for patients to know that drugs that alter brain chemistry can produce many beneficial outcomes, but many unusual side effects are possible. We simple do not know enough about the brain to accurately predict exactly what a drug will do in a particular patient.

What is fascinating to me, is that when these surprise side effects occur it is often a catalyst for new studies that explore how to take advantage of the side effect in a positive way. This is how we got Viagra, studied for blood pressure, making billions as a erection aid; Zyban, being used as the antidepressant Wellbutrin and patients were spontaneously quitting smoking; the SSRIs help with PMS and have been studied and tinkered with in attempts to use them for menopausal symptoms and premature ejaculation. There are many other example but I think you get the idea. Pharmacy can be so much fun!