Apomorphine hydrochloride is a non-ergoline dopamine agonist. Apomorphine hydrochloride is chemically designated as 6ab-Aporphine-10,11-diol hydrochloride hemihydrate with a molecular formula of C17H17NO2 • HCl • 1/2H2O. Apomorphine hydrochloride appears as minute, white or grayish-white glistening crystals or as white powder that is soluble in water at 80°C.
Apomorphine is a dopamine agonist administered as an intermittent or continuous subcutaneous infusion. It is reserved for troublesome dyskinesias in advanced PD as well as improving akinesia and rigidity. Because apomorphine is a dopamine agonist that acts on areas of the central nervous system believed to mediate penile erection, its use in erectile dysfunction (ED) has been investigated. However, it also produces nausea by dopamine-receptor stimulation of the chemotrigger zone in the brain. Therefore, a low plasma concentration, achieved rapidly, would be selective for the desired erectile response but would be below the dopamine threshold for nausea.
Apomorphine pills have been available in Europe for treating erectile dysfunction (ED) for two years, but the British firm Vectura is now trying to raise cash to develop an inhaled version of the drug. In clinical trials, inhaled apomorphine helped 60% of men get erections. Best of all, the drug took effect on average just eight minutes after use. "This is what people want, something that acts quickly," says Chris Blackwell, of Vectura. Because the drug is inhaled, and the lungs have a rich blood supply and a surface area as big as two tennis courts, the drug gets into the blood, and into the brain where it gets to work, faster than if taken as a pill.