Pentamidine isethionate

Chemical Properties

White or almost white powder or colourless crystals, hygroscopic.

Originator

Nebupent,Fujisawa Healthcare Inc ,USA

Uses

Pentamidine isethionate salt has been used:

• as a positive control for anti-leishmanial, anti-plasmodial and cytotoxic assays
• as a prototypical compound to analyse the inhibitor effect on human ether-a-go-go-related gene (HERG) K⁺ channel trafficking
• as an anti-leishmanial agent in promastigotes

Uses

Has been widely used as a drug to treat protozoal diseases, such as malaria, amoebic dysentery and trypanosomiasis. It has also been shown to be effective for both prophylaxis of pneumocystic carinii pneumonia (PCC).

Uses

Antiparasitic

Definition

ChEBI: An organosulfonate salt obtained by reaction of pentamidine with two equivalents of 2-hydroxyethylsulfonic acid.

Manufacturing Process

2.5 g of p,p'-dicyano-1,5-diphenoxy-pentane (obtained by the interaction of phydroxybenzonitrile and pentamethylene-dibromide in aqueous alkaline solution, melting point 114°C) are dissolved in 15 cc of nitrobenzene and 2.5 cc of absolute ethyl alcohol added. The solution is saturated with dry hydrochloric acid gas at 0°C and allowed to stand for 48 h. It is then diluted with dry ether and the precipitated 1,5-diphenoxypentane, 4,4'di(ethoxycarbonimidoyl) dihydrochlorid is filtered and washed with ether.
4 g of 1,5-diphenoxypentane, 4,4'-di(ethoxycarbonimidoyl) dihydrochloride are mixed with 30 cc. of 6 % ethyl alcoholic ammonia and heated in a closed vessel at 50°C for 5 h. The alcohol is removed and the residual 1,5diphenoxypentane, 4,4'-diamidino dihydrochloride is twice recrystallised fromdilute hydrochloric acid and finally purifled by dissolving in water and precipitating with acetone. Its melts at 236°C, dec.
Pentamidine isetionate salt may be produced by the reaction pentamidine base with isethionic acid.

Therapeutic Function

Antiprotozoal

General Description

Odorless white or almost white crystals or powder. Odor also reported as a slight butyric odor. Very bitter taste. pH (5% aqueous solution) 4.5-6.5.

Air & Water Reactions

Hygroscopic. May be sensitive to prolonged exposure to air. Aqueous solutions deteriorate on storage. Water soluble.

Reactivity Profile

Can decompose on prolonged exposure to light.

Fire Hazard

Flash point data for Pentamidine isethionate are not available; however, Pentamidine isethionate is probably combustible.

Biological Activity

Antimicrobial. Neuroprotective; inhibits constitutive nitric oxide synthase in the brain and acts as a NMDA glutamate receptor antagonist.

Biochem/physiol Actions

Neuroprotective; inhibits constitutive nitric oxide synthase in the brain; NMDA glutamate receptor antagonist.

Clinical Use

4,4’-(Pentamethylenedioxy)dibenzamidine diisethionate(NebuPent, Pentam 300) is a water-soluble crystalline saltthat is stable to light and air. The principal use of pentamidineis for the treatment of pneumonia caused by the opportunisticpathogenic protozoan P. carinii, a frequent secondaryinvader associated with AIDS. The drug may beadministered by slow intravenous infusion or by deep intramuscularinjection for PCP. An aerosol form of pentamidineis used by inhalation for the prevention of PCP inhigh-risk patients infected with HIV who have a previoushistory of PCP infection or a low peripheral CD4+ lymphocytecount.
Pentamidine has been used for the prophylaxis and treatmentof African trypanosomiasis. It also has some value fortreating visceral leishmaniasis. Pentamidine rapidly disappearsfrom the plasma after intravenous injection and is distributedto the tissues, where it is stored for a long period.This property probably contributes to the usefulness of thedrug as a prophylactic agent.

Drug interactions

Potentially hazardous interactions with other drugs
Anti-arrhythmics: increased risk of ventricular arrhythmias with amiodarone - avoid; possible increased risk of ventricular arrhythmias with disopyramide.
Antibacterials: increased risk of ventricular arrhythmias with delamanid, moxifloxacin and parenteral erythromycin - avoid with moxifloxacin; increased risk of ventricular arrhythmias with parenteral pentamidine and telithromycin.
Antidepressants: increased risk of ventricular arrhythmias with tricyclics; increased risk of ventricular arrhythmias with citalopram and escitalopram - avoid.
Antimalarials: increased risk of ventricular arrhythmias with piperaquine with artenimol - avoid.
Antipsychotics: increased risk of ventricular arrhythmias with amisulpride, droperidol and phenothiazines - avoid with amisulpride and droperidol.
Antivirals: increased risk of hypocalcaemia with parenteral pentamidine and foscarnet; increased risk of ventricular arrhythmias with saquinavir - avoid.
Cytotoxics: increased risk of ventricular arrhythmias with vandetanib - avoid.
Ivabradine: increased risk of ventricular arrhythmias.

Metabolism

Extensively hepatically metabolised.
Renal clearance accounts for <5% of the plasma clearance of pentamidine.