Orexigenic

An orexigenic, or appetite stimulant, is a drug, hormone, or compound that increases appetite. This can be a naturally occurring neuropeptide hormone such as ghrelin, orexin or neuropeptide Y,^[1][2] or a medication which increases hunger and therefore enhances food consumption. Usually appetite enhancement is considered an undesirable side effect of certain drugs as it leads to unwanted weight gain,^[3][4][5] but sometimes it can be beneficial and a drug may be prescribed solely for this purpose, especially when the patient is suffering from severe appetite loss or muscle wasting due to cystic fibrosis, anorexia, old age, cancer or AIDS.^{[6][7][8][9][10]} There are several widely used drugs which can cause a boost in appetite, including tricyclic antidepressants (TCAs), tetracyclic antidepressants, natural or synthetic cannabinoids, first-generation antihistamines, most antipsychotics and many steroid hormones.

Agents with orexigenic effects include the following:

• 5-HT_2C receptor antagonists/inverse agonists — mirtazapine, olanzapine, quetiapine, amitriptyline, cyproheptadine, lurasidone
• H₁ receptor antagonists/inverse agonists — mirtazapine, olanzapine, quetiapine, amitriptyline, cyproheptadine
• Dopamine antagonists — haloperidol, chlorpromazine, olanzapine, risperidone, quetiapine
• Adrenergic antagonists:
  • β blockers — propranolol, etc.
  • α₂ adrenergic antagonists — mirtazapine, mianserin
  • Mixed α₁/β blockers — carvedilol
• α2 Adrenergic agonists — clonidine
• CB₁ receptor agonists (cannabinoids — THC/dronabinol (a component of Cannabis), nabilone
• Corticosteroids — dexamethasone, prednisone, hydrocortisone
• Certain pregnene steroids — megestrol acetate, medroxyprogesterone acetate
• Anabolic steroids — oxandrolone, nandrolone, testosterone
• Sulfonylurea antidiabetic drugs such as glibenclamide, chlorpropamide and tolbutamide
• Mood stabilizers such as lithium
• Some anti-epileptic drugs such as valproate, carbamazepine and gabapentin^[11]
• α₂δ VDCC ligands — gabapentin, pregabalin^[12]
• Ghrelin receptor agonists such as anamorelin, GHRP-6, ibutamoren, ipamorelin, and pralmorelin
• MC₄ receptor antagonists
• Insulin
• Sugars such as fructose^[13]

See also

• Anorectic
• Anorexia
• Eating disorder
• Obesity
• Obesogen
• Organic feeding disorder
• Polydipsia
• Polyphagia (or hyperphagia)

References

Further reading

• Archer, Melissa; Steinvoort, Carin; Larson, Bryan; Oderda, Gary (2014). "Agents Used as Appetite Stimulants: Drug Class Review" (PDF). University of Utah College of Pharmacy.  Page 3: "Executive Summary".