Drug/Small Molecule:

clonidine

An alpha-2 adrenergic agonist that crosses the blood-brain barrier. Clonidine acts centrally by reducing sympathetic tone, resulting in a fall in diastolic and systolic blood pressure and a reduction in heart rate. It also acts peripherally, and this peripheral activity may be responsible for the transient increase in blood pressure seen during rapid intravenous administration. (From Martindale, the Extra Pharmacopoeia, 30th ed, p350) (source: Drug Bank)

For the treatment of hypertension and maybe used in prophylaxis of migraine or recurrent vascular headache; Menopausal flushing (source: Drug Bank)

Clonidine acts as an agonist at presynaptic alpha(2)-receptors in the nucleus tractus solitarius of the medulla oblongata. Stimulation of these receptors results in the supression of efferent sympathetic pathways and the subsequent decrease in blood pressure and vascular tone in the heart, kidneys, and peripheral vasculature. Clonidine is also a partial agonist at presynaptic alpha(2)-adrenergic receptors of peripheral nerves in vascular smooth muscle. (source: Drug Bank)

Clonidine is an antihypertensive agent and an epidural agent for refractory cancer pain. Similar to guanabenz in mechanism of action, clonidine is used in the treatment of hypertension, opiate and nicotine withdrawal, vascular headaches, diabetic diarrhea, glaucoma, ulcerative colitis, Gilles de la Tourette's syndrome, menopause symptoms, severe pain in cancer patients refractory to opiate agonists, and neuropathic pain and in the diagnosis of pheochromocytoma. (source: Drug Bank)

Avoid alcohol.
Take without regard to meals. (source: Drug Bank)

Hepatic. Metabolized through minor pathways. The major metabolite, p-hydroxyclonidine, is present in concentrations less than 10% of those of unchanged clonidine in urine. (source: Drug Bank)

20-40% (source: Drug Bank)

Well absorbed following oral administration. Bioavailability following chronic administration is approximately 65%. (source: Drug Bank)

Oral LD50 is 150 mg/kg in rat and 30 mg/kg in dog. Symptoms of overdose include constriction of pupils of the eye, drowsiness, high blood pressure followed by a drop in pressure, irritability, low body temperature, slowed breathing, slowed heartbeat, slowed reflexes, and weakness. (source: Drug Bank)

c1cc(c(c(c1)Cl)N=C2NCCN2)Cl (source: Drug Bank)