Headache receptors

Combined Hj /H2 receptor stimulation by histamine is responsible for vasodilation-related symptoms, such as hypotension, flushing, and headache, as well as for tachycardia stimulated indirecdy through vasodilation and catecholamine secretion. 

Antidepressants are used in the treatment of neuropathic pain and headache. They include the classic tricyclic compounds and are divided into nonselective nor-adrenaline/5-HT reuptake inhibitors (e.g., amitriptyline, imipramine, clomipramine, venlafaxine), preferential noradrenaline reuptake inhibitors (e.g., desipramine, nortriptyline) and selective 5-HT reuptake inhibitors (e.g., citalopram, paroxetine, fluoxetine). The reuptake block leads to a stimulation of endogenous monoaminer-gic pain inhibition in the spinal cord and brain. In addition, tricyclics have NMDA receptor antagonist, endogenous opioid enhancing, Na+ channel blocking, and K+ channel opening effects which can suppress peripheral and central sensitization. Block of cardiac ion channels by tricyclics can lead to life-threatening arrhythmias. The selective 5-HT transporter inhibitors have a different side effect profile and are safer in cases of overdose [3]. 

Several nonpeptidic, orally active vasopressin receptor antagonists have been developed. The dual V1A/V2R antagonist conivaptan is used in the treatment of hyponatraemia and could also become useful for diseases such as congestive heart failure, in which increased peripheral resistance and dilutional hyponatremia both are present [4]. Side effects of conivaptan include headache, injection site reactions, vomiting, diarrhoea, constipation and thirst. 

Antihistamines are commonly used to prevent and treat nausea and vomiting due to motion sickness, vertigo, or migraine headache.1,17 Their efficacy is presumably due to the high concentration of histamine (Hx) and muscarinic cholinergic receptors within the vestibular system. Similarly to scopolamine, antihistamines such as diphenhydramine and... 

Tegaserod maleate (Zelnorm) is a partial serotonin (5-HT4) receptor agonist that causes an increase in peristaltic activity and intestinal secretion and moderation of visceral sensitivity. It increases the frequency of bowel movements and reduces abdominal discomfort, bloating, and straining. It is indicated for the treatment of patients younger than 65 years of age who experience chronic idiopathic constipation. The most common adverse effects include headache, abdominal pain, diarrhea, and nausea. 

Yohimbine is an indole alkaloid produced in the bark of yohimbe trees. It selectively inhibits a2-adrenergic receptors in the brain that are associated with libido and penile erection. Since there is only limited data supporting its efficacy, yohimbine is not a recommended treatment for any form of ED.22 Adverse effects of the drug include nausea, irritability, headaches, anxiety, tachycardia, and hypertension. 

Rituximab is a monoclonal antibody to the CD20 receptor expressed on the surface of B lymphocytes the presence of the antibody is determined during flow cytometry of the tumor cells. Cell death results from antibody-dependent cellular cytotoxicity. The pharmacokinetics of rituximab are best described by a two-compartment model, with a terminal half-life of 76 hours after the first infusion and a terminal half-life of 205 hours after the fourth dose.36 Rituximab has shown clinical activity in the treatment of B-cell lymphomas that are CD20+. Side effects include hypersensitivity reactions, hypotension, fevers, chills, rash, headache, and mild nausea and vomiting. 

The often severe headaches, common in caffeine withdrawal, appear to be caused by vasodilation of cerebral blood vessels. This action is probably mediated by the action of the methylxanthines on adenosine receptors. 

Trastuzumab (Herceptin) -humanized mouse monoclonal antibody directed against HER-2/new receptor -fevers, chills, nausea, vomiting, headache during administration -cardiotoxicity (the FDA has not approved concurrent use with doxorubicin)... 

Ramelteon is a melatonin receptor agonist selective for the MTj and MT2 receptors. The dose is 8 mg at bedtime. It is well tolerated, but side effects include headache, dizziness, and somnolence. It is not a controlled substance. 

Zolpidem, chemically unrelated to benzodiazepines or barbiturates, acts selectively at the y-aminobutyric acidA (GABAA)-receptor and has minimal anxiolytic and no muscle relaxant or anticonvulsant effects. It is comparable in effectiveness to benzodiazepine hypnotics, and it has little effect on sleep stages. Its duration is approximately 6 to 8 hours, and it is metabolized to inactive metabolites. Common side effects are drowsiness, amnesia, dizziness, headache, and GI complaints. Rebound effects when discontinued and tolerance with prolonged use are minimal, but theoretical concerns about abuse exist. It appears to have minimal effects on next-day psychomotor performance. The usual dose is 10 mg (5 mg in the elderly or those with liver impairment), which can be increased up to 20 mg nightly. Cases of psychotic reactions and sleep-eating have been reported. 

Zaleplon also binds to the GABAa receptor. It has a rapid onset, a half-life of about 1 hour, and no active metabolites. It does not reduce nighttime awakenings or increase the total sleep time. It may be best used for middle-of-the-night awakenings. It does not appear to cause significant rebound insomnia or next-day psychomotor impairment. The most common side effects are dizziness, headache, and somnolence. The recommended dose is 10 mg (5 mg in the elderly). 

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