Pharmacodynamics<unk>  interacts with serotonin, adrenergic, and dopamine receptors. It is an agonist of serotonin receptors including the 5-HT1 and 5-HT2 subtypes.<unk>  is an agonist of the serotonin 5-HT2B receptor and has been associated with cardiac valvulopathy. Despite acting as a potent 5-HT2A receptor agonist,<unk>  is said to be non-hallucinogenic similarly to lisuride. This is thought to be due to functional selectivity at the 5-HT2A receptor. + Site Affinity (Ki/IC50 nM) Efficacy (Emax %) Action 5-HT1A 0.17–0.3 ? Full agonist 5-HT1B 0.3–4.7 ? Agonist 5-HT1D 0.3–6.0 ? Agonist 5-HT1E 19–840 ? ? 5-HT1F 170–171 ? ? 5-HT2A 0.64–0.97 ? Full agonist 5-HT2B 1.3–45 ? Partial agonist 5-HT2C 1.9–9.8 ? Partial agonist 5-HT3 >10,000 – – 5-HT4 65 ? ? 5-HT5A 14 ? Agonist 5-HT5B 3.2–16 ? ? 5-HT6 12 ? ? 5-HT7 1,291 ? Agonist α1A 15–>10,000 – – α1B 12–>10,000 – – α1D ? ? ? α2A 106 ? ? α2B 88 ? ? α2C >10,000 – – β1 >10,000 – – β2 >10,000 – – D1 >10,000 – – D2 4.0–>10,000 – Agonist D3 3.2–>10,000 – – D4 12–>10,000 – – D5 170 ? ? H1 >10,000 – – H2 >10,000 – – M1 862 ? ? M2 911 ? ? M3 >10,000 – – M4 >10,000 – – M5 >10,000 – – Notes: All receptors are human except 5-HT5A (mouse/rat) and 5-HT5B (mouse/rat—no human counterpart). No affinity for histamine H1 or H2, cannabinoid CB1, GABA, glutamate, or nicotinic acetylcholine receptors, nor the monoamine transporters (all >10,000 nM). Pharmacokinetics The bioavailability of<unk>  is around 2% orally, 6% rectally, and 100% by intramuscular or intravenous injection. The low oral and rectal bioavailability is due to low gastrointestinal absorption and high first-pass metabolism.
Ergotamine
Dihydroergotamine
Metergoline
Altretamine
Sodium nitroprusside
Phentolamine
Papaverine
Nicergoline