Appetite Stimulants (Orexiants)

Appetite Stimulants (Orexiants)

Appetite Stimulants (Orexiants) are drugs that increase hunger and food intake by acting on central appetite-regulating pathways.

Indications

• Anorexia
• Cancer cachexia
• HIV/AIDS-associated wasting
• Depression-related weight loss
• Geriatric undernutrition

Classes of Appetite Stimulants

1. Antihistamines (H1 blockers)

   • Examples: Cyproheptadine
   • Mechanism: H1 receptor antagonism + 5-HT2 receptor blockade → ↑ appetite
   • Use: Pediatric and geriatric anorexia, failure to thrive

2. Corticosteroids

   • Examples: Prednisolone, Dexamethasone
   • Mechanism: Anti-inflammatory + central effect on appetite centers
   • Use: Short-term in cancer cachexia, terminal illness
   • Note: Long-term use → side effects (Cushingoid features, hyperglycemia)

3. Cannabinoids

   • Examples: Dronabinol (synthetic THC)
   • Mechanism: CB1 receptor agonist → ↑ appetite, mood elevation
   • Use: AIDS-related anorexia, chemotherapy-induced nausea

4. Anabolic Steroids

   • Examples: Oxandrolone
   • Mechanism: Promote protein synthesis and stimulate appetite
   • Use: Wasting syndromes, malnutrition

5. Tricyclic Antidepressants (TCAs)

   • Examples: Mirtazapine
   • Mechanism: Enhances noradrenaline and serotonin → increased appetite
   • Use: Depression with weight loss

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