What is Pentamidine?
The drug Pentamidine is broadly classified under anti-protozoal drugs. Several diamidine compounds have trypanocidal action, including pentamidine. In the treatment of visceral leishmaniasis, pentamidine isethionate is utilized instead of sodium stibogluconate. It can also be used to treat early trypanosomiasis.
Pentamidine Mechanism of Action
The precise mechanism has yet to be discovered. However, it is believed that positively charged lipophilic diamidines can kill trypanosomes by interacting with RNA, and DNA, and membrane phospholipids, all are negative charge carrying intracellular targets.
The loss of kinetoplast DNA, ribosomal aggregation, and inhibition of numerous enzymes have all been observed. Additionally, the medication has been demonstrated to block trypanosomal S-adenosyl-L-methionine decarboxylase, thus lowering polyamine formation.
Pharmacokinetics
How is Pentamidine administered?
It is administered predominantly parenterally, as the drug exhibits poor absorption when administered via the oral route. Upon oral administration, pentamidine shows very poor bioavailability. Inhalational preparations of this drug are also available.
Distribution and Metabolism
The drug does not seem to cross the blood-brain barrier. This is the reason it is not a suitable choice once the organism invades the central nervous system (CNS). It is believed to be retained in man’s tissues by tissue binding and eliminated over a prolonged period of time. The drug is 70% bound to plasma proteins with a half-life of approximately 0.9 hours following IV (intravenous) administration.
Excretion
Maximum levels of the drug can be traced in kidneys. The drug is excreted through urine.
Pentamidine Uses
- Trypanosoma brucei gambiense infections (in combination with the drug suramin)
- Visceral leishmaniasis
- Cutaneous leishmaniasis
- Pneumocystis infection
- Pneumocystis pneumonia prophylaxis
- For patients who cannot take antimonial or lipid formulations of amphotericin B, it is administered as an alternative.
Pentamidine Contraindications
It is contraindicated if the patient shows hypersensitivity to the drug or any other diamidine product.
Other contraindications include:
- Late-stage trypanosomiasis
Cases that need extra care are patients with
- Diabetes
- Hypertension
- Hepatic disease
- Renal disease
Pentamidine Adverse Effects
A wide majority of the patients taking this drug experience side effects.
Common Side effects
- Pain
- Swelling at the injection site
- Hypotension
- Vomiting
- Blood dyscrasias
- Renal damage
Less frequently occurring side effects
- Diabetes
- Hypoglycemic shock (can occur during treatment or even weeks after treatment. Can be life-threatening)
- Liver damage
Rare side effects
- Herxheimer reactions
If the drug is administered too rapidly, it may cause hypotensive tachycardia and headache.
Pentamidine Interactions
Pentamidine shows interactions with the following drugs:
Acecainide, Astemizole, Bepridil, Bretyllium, Chloroquine, Chlorpromazine, Prochlorperazine, Triflupromazine, Cisapride, Disopyramide, Dolasetron, Droperidol, Enchained, Flecainide, Erythromycin, Clarithromycin, Telithromycin, Enflurane, Halothane, Fluconazole, Fluoxetine, Foscarnet, Fluoroquinolones (Grepafloxacin, Gemifloxacin), Halofantrine, mefloquine, Haloperidol, Octreotide, Procainamide, Sotalol, Risperidone, Trimethoprim, Insulin Aspart, Detemir, Glargine, Glulisine, Inhaled insulin.
Pentamidine Isethionate Brands
- NebuPent
- Pentam
- Pentacarinat
- Pentam 300
Can I take Pentamidine if I am pregnant or breastfeeding? / IS Pentamidine safe in pregnancy?
The FDA has classified pentamidine as a pregnancy category C drug. When given intravenously (IV) to pregnant rats at a dose of 4 mg/kg/day, animal studies show pieces of evidence of embryo lethality. There is no experimental data available for this in human pregnancy, and it is unclear whether it can affect a fetus if administered during pregnancy.
Pentamidine should only be used in pregnancy if there are no other options and the benefit outweighs the risk. As it has the potential to cause major serious side effects in nursing infants, a decision needs to be made whether to stop breastfeeding or stop taking the medicine, considering the drug’s significance to the mother.
Pentamidine should not be given to a breastfeeding mother unless the potential benefits are assessed to exceed the unknown risks.