Pentamidine Isethionate

Pronunciation: pen-TAM-ih-deen ice-uh-THIGH-uh-nate
Class: Antiprotozoal

Trade Names

NebuPent
- Aerosol 300 mg

Pentacarinat
- Injection 300 mg

Pentam 300
- Injection 300 mg

Pharmacology

Mechanism of action not fully understood. Interferes with synthesis of DNA, RNA, phospholipids, and proteins.

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Pharmacokinetics

Absorption

Well absorbed after IM administration and detectable in the blood briefly because of extensive tissue binding.

C max is 612 ng/mL (single 2-h IV infusion).

T max is 0.5 to 1 h (IM), 1 to 2 h (IV).

Distribution

Rapidly distributed with highest concentrations in liver, kidneys, adrenal glands, and spleen; smaller amount in lungs, and slow uptake into CNS and brain tissue.

Vd is 3 to 32 L/kg (at steady state).

Metabolism

Unknown in humans.

Elimination

Urine (12% as unchanged).

T ½ is 6.4 h (IV), 9.1 to 13.2 h (IM).

Cl is 248 L/h (IV).

Terminal t ½ is 2 to 4 wk.

Special Populations

Renal Function Impairment

Pentamidine may accumulate in renal failure.

Indications and Usage

Parenteral form

Treatment of Pneumocystis carinii pneumonia (PCP).

Inhalation

Prevention of PCP in high-risk HIV-infected patients.

Unlabeled Uses

Treatment of trypanosomiasis and visceral leishmaniasis.

Contraindications

Parenteral form

Once diagnosis of PCP is made, there are no absolute contraindications.

Inhalation

History of anaphylactic reaction to pentamidine.

Dosage and Administration

Adults and Children

IM / IV 4 mg/kg every day for 14 days.

Adults

Inhalation 300 mg once every 4 wk administered via Respirgard II nebulizer.

General Advice

Injection
  • Dissolve contents of vial in sterile water for injection or D5W as directed.
  • For IV infusion, solution may be diluted further in D5W.
  • Infuse pentamidine IV over 1 h with patient supine to minimize severe hypotension and arrhythmias.
  • For IM administration, inject deeply and rotate sites.
Inhalation
  • Reconstitute medication for inhalation in sterile water for injection. Do not mix with any other drugs.
  • Deliver aerosol dose until nebulizer chamber is empty (approximately 30 to 45 min).

Storage/Stability

  • Reconstituted aerosol preparation is stable up to 48 h at room temperature, if protected from light source. Discard unused portion.
  • IV solutions prepared with D5W are stable at room temperature for up to 48 h. Discard unused portion.
  • Store unopened vial at controlled room temperature (59° to 86°F). Protect from light.

Drug Interactions

Incompatibility

Do not reconstitute with saline solutions. Do not mix with other drugs.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypotension; ventricular tachycardia; cardiac arrhythmias; chest pain; edema; phlebitis.

CNS

Confusion; hallucinations; dizziness; fatigue; headache.

Dermatologic

Stevens-Johnson syndrome; sterile abscess, pain or induration at IM injection site; rash.

EENT

Bad or metallic taste.

GI

Nausea; anorexia; vomiting; diarrhea; abdominal pain.

Genitourinary

Acute renal failure; elevated serum creatinine.

Hematologic

Leukopenia; thrombocytopenia; anemia; pancytopenia.

Hepatic

Elevated LFT results.

Metabolic

Hypoglycemia; hypocalcemia; hyperkalemia.

Respiratory

Shortness of breath; cough; pharyngitis; chest congestion; bronchospasm; pneumothorax (generally associated with inhalation).

Miscellaneous

Neuralgia; myalgia; night sweats, chills.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy of inhalation solution not established.

Renal Function

Reduction of dosage, longer infusion time, or extension of dosing interval may be required.

Special Risk Patients

Use drug with caution in patients with hypertension, hypotension, hypoglycemia, hyperglycemia, hypocalcemia, leukopenia, thrombocytopenia, anemia, hepatic or renal function impairment, ventricular tachycardia, pancreatitis, Stevens-Johnson syndrome.

Development of acute PCP

Acute PCP may develop despite pentamidine prophylaxis.

Fatalities

Fatalities from severe hypotension (even after one dose), hypoglycemia and cardiac arrhythmias have been reported with IM and IV routes. Monitor BP continuously throughout infusion, every 30 min for 2 h thereafter and then every 4 h until BP stabilizes.

Patient Information

  • Inform the patient that there may be pain at the injection site with IM administration.
  • Caution patient to avoid crowds and persons with known infections.
  • Instruct patient to report the following symptoms to health care provider: nausea, vomiting, anorexia, diarrhea, oliguria, dizziness, chest pain, or edema.
  • Advise patient that drug may cause dizziness, and to use caution while driving or performing other tasks requiring mental alertness.

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