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Ismelin: Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Ismelin - General Information

An antihypertensive agent that acts by inhibiting selectively transmission in post-ganglionic adrenergic nerves. It is believed to act mainly by preventing the release of norepinephrine at nerve endings and causes depletion of norepinephrine in peripheral sympathetic nerve terminals as well as in tissues. [PubChem]

 

Pharmacology of Ismelin

High blood pressure can cause the heart and arteries to not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled. Ismelin works by decreasing the heart rate and relaxing the blood vessels so that blood can flow more easily through the body, thereby reducing these risks. It is a postganglionic sympathetic nerve terminal blocker that prevents the release of norepinephrine from nerve terminals.

 

Ismelin for patients

 

Ismelin Interactions

https://www.rxlist.com/cgi/generic3/guanethidine_od.htm

 

Ismelin Contraindications

Known or suspected pheochromocytoma; hypersensitivity; frank congestive heart failure not due to hypertension; use of monoamine oxidase (MAO) inhibitors.

 

Additional information about Ismelin

Ismelin Indication

For the treatment of moderate and severe hypertension, either alone or as an adjunct, and for the treatment of renal hypertension.

Mechanism Of Action
Ismelin acts at the sympathetic neuroeffector junction by inhibiting or interfering with the release and/or distribution of norepinephrine, rather than acting at the effector cell by inhibiting the association of norepinephrine with its receptors. In contrast to ganglionic blocking agents, Ismelin suppresses equally the responses mediated by alpha-and beta-adrenergic receptors but does not produce parasympathetic blockade. Since sympathetic blockade results in modest decreases in peripheral resistance and cardiac output, Ismelin lowers blood pressure in the supine position. It further reduces blood pressure by decreasing the degree of vasoconstriction that normally results from reflex sympathetic nervous activity upon assumption of the upright posture, thus reducing venous return and cardiac output more.
Drug Interactions
Acetophenazine The agent decreases the effect of guanethidine
Food Interactions
Take without regard to meals.
Generic Name
Guanethidine
Synonyms
Guanethidine Monosulfate; Guanethidine Sulphae
Drug Category
Adrenergic Agents; Antihypertensive Agents; Sympatholytics
Drug Type
Small Molecule; Approved
Other Brand Names containing Guanethidine
Apo-Guanethidine; Ismelin; Eutensol; Abapresin; Oktadin;
Absorption
3-30% of oral dose (poor and highly variable)
Toxicity (Overdose)
Side effects include drowsiness, dizziness, tiredness or confusion. LD50=1000 mg/kg (mouse, oral)
Biotransformation
Guanethidine is converted by the liver to three metabolites, which are excreted in the urine. The metabolites are pharmacologically less active than the parent compound.
Half Life
1.5 days
Dosage Forms of Ismelin
Tablet Oral
Chemical IUPAC Name
2-[2-(azocan-1-yl)ethyl]guanidine
Chemical Formula
C10H22N4
Organisms Affected
Humans and other mammals