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, 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,  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. 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-HT2C receptor antagonists/inverse agonists – mirtazapine, olanzapine, quetiapine, amitriptyline, cyproheptadine
 * H1 receptor antagonists/inverse agonists – mirtazapine, olanzapine, quetiapine, amitriptyline, cyproheptadine
 * Dopamine antagonists – haloperidol, chlorpromazine, olanzapine, risperidone, quetiapine
 * Adrenergic antagonists – carvedilol, propranolol; 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 – glibenclamide and chlorpropamide