Pentoxifylline

Pronunciation

Pronunciation: pen-tox-IH-fi-leen
Class: Hemorrheologic agent

Trade Names

Trental
- Tablets, controlled-release 400 mg

Pentoxil
- Tablets, controlled-release 400 mg

Apo-Pentoxifylline SR (Canada)
ratio-Pentoxifylline (Canada)

Pharmacology

Improves blood flow by decreasing blood viscosity.

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Pharmacokinetics

Absorption

Pentoxifylline is almost completely absorbed. Food delays absorption and increases C max by 28% and AUC by 13%. T max is 1 h (parent drug and metabolites).

Distribution

Protein binding to erythrocyte membrane. Both parent drug and metabolites distribute into breast milk.

Metabolism

Extensive first-pass metabolism. Undergoes first-pass effect; in the liver, some metabolites are active with 5 to 8 times the plasma levels of the parent drug.

Elimination

Urine (as metabolites), fecal (less than 4%). The plasma t ½ is 0.4 to 0.8 h (parent drug) and 1 to 1.6 h (metabolites).

Onset

2 to 4 wk (multiple doses).

Special Populations

Elderly

Increases AUC and decreases elimination rate (60 to 68 yr of age).

Indications and Usage

Intermittent claudication on basis of chronic occlusive arterial disease of limbs.

Unlabeled Uses

Treatment of psychopathological symptoms in patients with cerebrovascular insufficiency; treatment of diabetic angiopathies and neuropathies, transient ischemic attacks, leg ulcers, sickle cell thalassemias, strokes, high-altitude sickness, asthenozoospermia, acute and chronic hearing disorders, severe idiopathic recurrent aphthous stomatitis, eye circulation disorders, and Raynaud phenomenon.

Contraindications

Intolerance to methylxanthines (eg, caffeine, theophylline); recent cerebral and/or retinal hemorrhage.

Dosage and Administration

Adults

PO 400 mg 3 times daily with meals for at least 8 wk. If GI and CNS adverse reactions occur, decrease to 400 mg twice daily. If adverse reactions persist, discontinue.

Storage/Stability

Store at 59° to 86°F. Protect from light.

Drug Interactions

Antihypertensives

Small decreases in blood pressure possible in patients receiving pentoxifylline while using antihypertensive drugs. Monitor BP. If indicated, reduce dosage of the antihypertensive.

Cimetidine

Effects of pentoxifylline may be increased.

Theophylline

Coadministration with pentoxifylline leads to increased theophylline levels and possible toxicity in some patients. Monitor and adjust closely.

Warfarin

Bleeding and prolonged PT possible.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Arrhythmia/palpitation, flushing (2%); angina/chest pain (1%); dyspnea, edema, hypotension, tachycardia (postmarketing).

CNS

Dizziness (12%); headache (6%); agitation/nervousness, insomnia (2%); drowsiness (1%); anxiety, aseptic meningitis, confusion, depression, malaise, seizures (postmarketing).

Dermatologic

Brittle fingernails, pruritus, rash, urticaria (postmarketing).

EENT

Blurred vision (2%); conjunctivitis, earache, epistaxis, laryngitis, nasal congestion, scotoma, sore throat/swollen neck glands (postmarketing).

GI

Nausea (29%); dyspepsia (10%); belching/flatus/bloating (9%); vomiting (5%); abdominal discomfort (4%); diarrhea (3%); anorexia, bad taste, constipation, dry mouth/thirst, excessive salivation (postmarketing).

Hepatic

Cholecystitis, hepatitis, increased liver enzymes, jaundice (postmarketing).

Hematologic-Lymphatic

Aplastic anemia, decreased serum fibrinogen, leukemia, leukopenia, pancytopenia, purpura, thrombocytopenia (postmarketing).

Metabolic-Nutritional

Weight change (postmarketing).

Miscellaneous

Anaphylactoid reactions, angioedema, flu-like symptoms (postmarketing).

Precautions

Monitor

Periodically monitor patients with risk factors complicated by hemorrhage (eg, recent surgery, peptic ulceration, cerebral and retinal bleeding) for bleeding, including hematocrit and hemoglobin; patients receiving warfarin should have more frequent monitoring of PT.


Pregnancy

Category C .

Lactation

Excreted in breast milk.

Children

Safety and efficacy not established.

Elderly

Use with caution, usually starting at the low end of the dosage range, because of the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant diseases or other drug therapy.

Renal Function

Drug may accumulate, producing toxicity; lower dose may be necessary.

Hemorrhage

Periodically examine patients with risk of hemorrhage for bleeding.

Overdosage

Symptoms

Symptoms appear to be dose related. They usually occur 4 to 5 h after ingestion and last approximately 12 h. Symptoms include agitation, convulsions, fever, flushing, hypotension, loss of consciousness, and somnolence.

Patient Information

  • Explain that improvement in symptoms may take 2 to 4 wk to notice and up to 8 wk for max relief.
  • Explain importance of follow-up lab work for patients with high risk of bleeding or who are taking anticoagulants.
  • In patients with occlusive peripheral vasospastic disorders, emphasize use of self-help measures to augment drug therapy (eg, exercise, weight control, no smoking).
  • Review specifics of good foot care, including bathing of feet daily in lukewarm water and drying thoroughly, applying lanolin to feet after bathing, using lambswool between toes and feet, avoiding temperature extremes, wearing clean cotton socks daily.
  • Instruct patient to report the following symptoms to health care provider: abnormal bleeding, chest pain, dizziness, excessive bruising, fainting.
  • Advise patient that drug may cause dizziness, and to use caution while driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.

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