Guanfacine hydrochloride

Guanethidine monosulfate is a pharmacological agent that is primarily used in the management of hypertension. It is classified as an adrenergic neuron blocking drug, and it works by inhibiting the release of norepinephrine from nerve endings, thereby reducing the activity of the sympathetic nervous system.

Pharmacology

Guanethidine monosulfate is a potent sympatholytic drug that acts by depleting the storage of norepinephrine in the presynaptic nerve endings. It is transported into the nerve endings by the same mechanism that transports norepinephrine. Once inside the nerve endings, guanethidine replaces norepinephrine in the storage vesicles. This results in a reduction of the release of norepinephrine upon nerve stimulation.

Clinical Use

Guanethidine monosulfate is used in the treatment of hypertension. It is particularly effective in severe forms of hypertension where other treatments have failed. However, due to its side effects, it is usually considered a last-resort treatment.

Side Effects

The most common side effects of guanethidine monosulfate include orthostatic hypotension, sexual dysfunction, and diarrhea. Less common side effects include bradycardia, nasal congestion, and hyperglycemia.

Contraindications

Guanethidine monosulfate is contraindicated in patients with pheochromocytoma, a rare tumor of the adrenal gland, because it can cause a severe increase in blood pressure. It is also contraindicated in patients with heart block or other severe cardiac conditions.

Drug Interactions

Guanethidine monosulfate can interact with a number of other drugs, including tricyclic antidepressants, monoamine oxidase inhibitors, and phenothiazines. These interactions can lead to an increase in blood pressure and other adverse effects.