Haemorheologic agents

Xanthine derivatives that make blood flow more easily through narrowed small vessels. Pentoxifylline is used for intermittent claudication.

Updated Nov 12, 2026

What they are

Purine (xanthine) derivatives grouped by the WHO ATC system under peripheral vasodilators (C04AD). Pentoxifylline is the member in common use; it lengthens walking distance modestly in intermittent claudication and supports, but does not replace, exercise, smoking cessation and revascularisation. Cilostazol, the other drug for claudication, is on the antiplatelets page.

Mechanism of action

These drugs are related to caffeine and theophylline and inhibit phosphodiesterases. Red cells become more flexible, blood viscosity falls and white cells adhere and activate less, so blood passes more easily through narrowed small vessels in the limbs.

Target: Phosphodiesterases in blood cells (non-selective)

Drugs in this class

PentoxifyllineA methylxanthine that makes blood flow more easily (less viscous, more flexible red cells). Used for intermittent…Phosphodiesterases (non-selective; PDE4A shown)

Others in the class

Pentifylline
Xantinol nicotinate
Etofylline nicotinate

Test yourself

Think of the answer, then tap the question to see it.

What do haemorheologic agents change to improve flow in claudication?

The blood itself: red cells become more flexible and viscosity falls.

Which recent bleeding rules out pentoxifylline?

A recent cerebral or retinal haemorrhage.

Which bronchodilator's levels rise with pentoxifylline?

Theophylline.

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