Kleine–Levin syndrome (KLS) is a rare disorder characterized by persistent episodic hypersomnia and cognitive or mood changes. Many patients also experience hyperphagia, hypersexuality and other symptoms. Patients generally experience recurrent episodes of the condition for more than a decade and may return at a later age. Individual episodes generally last more than a week, sometimes lasting for months. The condition greatly affects the personal, professional, and social lives of those with KLS. The severity of symptoms and the course of the syndrome vary between those with KLS. Patients commonly have about 20 episodes over about a decade. Several months generally elapse between episodes. The onset of the condition usually follows a viral infection; several different viruses have been observed to trigger KLS. It is generally only diagnosed after similar conditions have been excluded; MRI, CT scans, lumbar puncture, and toxicology tests are used to rule out other possibilities. The syndromes mechanism is not known, but the thalamus is thought to possibly play a role. SPECT has shown thalamic hypoperfusion of patients during episodes. KLS is very rare, occurring at a rate of 1 in 1 million, which limits research into genetic factors. The condition primarily affects adolescent males, though females can also be affected and the age of onset varies. There is no known cure, and there is little evidence supporting drug treatment. Lithium has been reported to have limited effects in case reports, decreasing the length of episodes and duration between them in some patients.
Shortage or excess of dopamine can prevent proper function and signaling of these receptors leading to disease states.Apomorphine improves motor function by activating dopamine receptors in the nigrostriatal pathway, the limbic system, the hypothalamus, and the pituitary gland. It also increases blood flow to the supplementary motor area and to the dorsolateral prefrontal cortex (stimulation of which has been found to reduce the tardive dyskinesia effects of L-DOPA). Parkinsons has also been found to have excess iron at the sites of neurodegeneration; both the (R)- and (S)-enantiomers of apomorphine are potent iron chelators and radical scavengers.Apomorphine also decreases the breakdown of dopamine in the brain (though it inhibits its synthesis as well). It is an upregulator of certain neural growth factors, in particular NGF but not BDNF, epigenetic downregulation of which has been associated with addictive behaviour in rats.Apomorphine causes vomiting by acting on dopamine receptors in the chemoreceptor trigger zone of the medulla; this activates the nearby vomiting center. Pharmacokinetics
While apomorphine has lower bioavailability when taken orally, due to not being absorbed well in the GI tract and undergoing heavy first-pass metabolism, it has a bioavailability of 100% when given subcutaneously. It reaches peak plasma concentration in 10–60 minutes. Ten to twenty minutes after that, it reaches its peak concentration in the cerebrospinal fluid.