Nmda Receptor Antagonists – Analgesics, Case Reports and Obstetrical Pain

00:00 N-Methyl-D-aspartate receptor antagonist, MD and nMDA receptor antagonist can reduce central sensitization due to increased nMDA which is a central nervous system neurotransmitter. So ketamine is a general anesthetic which we have mentioned but in small doses it's an effective analgesic. It's also currently become drug of abuse and it has become street drug and the name on the street is special cake. Ketamine is also occasionally used for labor analgesia and analgesia prior to surgery but only in very small doses. When used as an anesthetic or with analgesic in higher doses, it can produce the recovery phenomena that I mentioned in a previous lecture. Other side effects include nausea and vomiting, increased heart rate and blood pressure, and occasionally agitation and hallucinations. Carrying on more drugs alpha-2 agonist, the classic of this is clonidine. These are receptor drugs that work on the alpha-2 receptor which is a central nervous system receptor. They can be given either orally or they can be given along with spinal anesthesia in a dilute concentration. They produce sedation and can produce severe postural hypotension. So in other words, when you stand up your blood pressure drops and that can lead to fainting or even loss of consciousness and seizure so that's not a good thing. They produce a very dry mouth and patients complain about that.

01:44 The newer drug Dexmedetomidine is an IV formulation that can be used for ICU sedation, procedural sedation and to decrease the use of opioids and generally anesthesia.

01:53 For migraine headache, there have been great problems finding substances that are useful and one of the agents of drugs that has been found to be useful in some people with migraine are the 5 hydroxytryptamine 1 agonist and the classic drug in this group is sumatriptan, but there's a series of drugs. They are used for treatment of migraine headaches. They can be self-administered by syringe, preloaded syringe. They can be even taken as tablets or you can actually use a nasal spray, which is quite quick because it's rapidly absorbed by the nasal mucosa and you're right near the brain when you administer it so it can actually be quite effective. They cause vasoconstriction, tightening of blood vessels, and reduction of inflammation of the cranial arteries. So the arteries that come on the outer surface of the skull primarily some of them perforate the skull and these are the arteries that become dilated and throbbing in migraine headache. This vasoconstriction can increase the risk in vascular bed such as a cardiac bed where if you get vasoconstriction you can get cardiac ischemia and myocardial infarction and it can also increase the possibility of stroke if it causes intracranial vessels also to constrict.