Pentoxifylline
Haemorheologic agents
Haemorheologic agents
A methylxanthine that makes blood flow more easily (less viscous, more flexible red cells). Used for intermittent claudication; modest benefit.
Also called: oxpentifylline
Quick facts
- Group
- Haemorheologic agents
- Target
- Phosphodiesterases (non-selective; PDE4A shown)
- Used for
- Sometimes used for venous leg ulcers
- Key effects
- Nausea · Dizziness
- Monitor
- Signs of bleeding · INR when given with warfarin
- ATC
- C04AD03
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows pentoxifylline in the active site of human phosphodiesterase 4A, one of the phosphodiesterases it inhibits.
Pentoxifylline is a xanthine derivative (related to caffeine and theophylline) that inhibits phosphodiesterases and raises cAMP in blood cells. Red cells become more flexible, blood viscosity falls, white cells are less able to stick and activate. Blood flows more easily through narrowed small vessels in the limbs, which can lengthen walking distance in claudication.
- Inhibits phosphodiesterases: cAMP rises in blood cells
- Red cells more flexible; blood less viscous
- White cells adhere and activate less
- Better microcirculatory flow in ischaemic limbs
Indications
- Intermittent claudication from chronic occlusive arterial disease of the limbs Peripheral artery disease →
- Sometimes used for venous leg ulcers Venous leg ulcer →
Adverse effects
Common
- Nausea, vomiting, upset stomach, wind
- Dizziness, headache
Contraindications
- Recent bleeding in the brain or retina
- Intolerance to pentoxifylline or other methylxanthines (caffeine, theophylline, theobromine)
Key interactions
- Warfarin and other vitamin K antagonists
- Prothrombin time may rise; INR is checked more often.
- Theophylline
- Higher theophylline levels and toxicity.
- Strong CYP1A2 inhibitors (ciprofloxacin, fluvoxamine) and cimetidine
- Higher pentoxifylline levels.
- Antihypertensives
- Small additional fall in blood pressure.
What is monitored
- Signs of bleeding; blood counts when bleeding risk is high
- INR when given with warfarin
- Blood pressure, especially with other cardiovascular drugs
- Walking distance and symptoms
Administration and safety
- Extended-release tablet with meals, swallowed whole, not broken, crushed or chewed.
- Benefit may take weeks; it supports, not replaces, exercise, smoking cessation or revascularisation.
- Surgeons and dentists are told that the patient takes it.
Pregnancy and breastfeeding
There are no adequate human studies; it is used only if the benefit justifies the possible risk to the fetus.
Nursing care
- Before: ask about recent bleeding (brain, eye, stomach) and caffeine or theophylline intolerance.
- During: teach to report bleeding, black stools, chest pain or palpitations.
- Check blood pressure; teach to take it with food to reduce nausea.
- Encourage supervised walking and smoking cessation.
Pharmacokinetics
- Absorption
- Oral extended-release tablet, almost completely absorbed, with a first-pass effect.
- Metabolism
- Extensively metabolised to active metabolites; exposure rises markedly in liver impairment.
- Elimination
- Almost entirely in the urine; metabolites accumulate in kidney impairment.
- Onset and duration
- Benefit appears over weeks.
Test yourself
Think of the answer, then tap the question to see it.
How does pentoxifylline improve blood flow?
It makes red cells more flexible and lowers blood viscosity (via phosphodiesterase inhibition).
Which bleeding history rules it out?
Recent cerebral or retinal haemorrhage.
Which drug's levels rise when given with pentoxifylline, since both are methylxanthines?
Theophylline.
Connections
← Back to the class: Haemorheologic agents
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Pentoxifylline: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2017); PENTOXIFYLLINE tablet, extended release (DailyMed (U.S. National Library of Medicine), 2026); The structure of PDE4A with pentoxifylline at 2.84A resolution (RCSB Protein Data Bank, 2012); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.