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5-HT2 Receptor Antagonist — Peripheral Arterial Disease (Intermittent Claudication) Pregnancy: In the absence of any relevant clinical data, the use of Praxilene is not advisable during pregnancy. Breast-feeding: in the absence of specific data concerning the excretion of the drug in human milk, Praxilene should not be used by breast-feeding women. (UK SPC §4.6)

Naftidrofuryl Oxalate

Brand names: Praxilene

Naftidrofuryl oxalate is a peripheral vasodilator used to relieve symptoms in intermittent claudication due to peripheral arterial disease.

Adult dose

Dose: Peripheral vascular disorders (incl. intermittent claudication): one or two 100 mg capsules (each capsule contains 100mg naftidrofuryl oxalate) per dose, three times daily
Route: Oral
Frequency: Three times daily, for a minimum of three months, or at the discretion of the physician
SPC §4.2 (verbatim): 'One or two capsules three times daily for a minimum of three months, or at the discretion of the physician.' Strength (§2): each capsule contains 100mg naftidrofuryl oxalate equivalent to 81.0 mg naftidrofuryl and 19.0 mg oxalate. §4.1: 'Peripheral vascular disorders - intermittent claudication, night cramps, rest pain, incipient gangrene, trophic ulcers, Raynaud's Syndrome, diabetic arteriopathy and acrocyanosis.' Oral only: 'The capsules should be swallowed whole during meals with a sufficient amount of water (minimum) of one glass.' §4.4: taking the capsule without liquid before going to bed may cause local oesophagitis. The SPC prints NO maximum dose, so none is stated. Children: 'This drug is not indicated for use in children.' Source product is the 100 mg capsule only (Praxilene 100mg Capsules).

Dose adjustments

Renal

The SPC gives no renal dose adjustment in §4.2. Contraindicated in patients with a history of hyperoxaluria or recurrent calcium-containing kidney stones (§4.3). §4.4: naftidrofuryl may modify the composition of the urine, promoting the formation of calcium oxalate kidney stones (oxalate content 19 mg per 100 mg of active ingredient); a sufficient amount of liquid should be taken to maintain an adequate level of diuresis.

Hepatic

The SPC gives no hepatic dose adjustment in §4.2. §4.4: cases of liver damage have been reported; in the event of symptoms suggesting liver damage, the medicine must be discontinued.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via MHRA Products — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients (§4.3)
  • History of hyperoxaluria or recurrent calcium-containing kidney stones (§4.3)

Side effects

  • Uncommon: diarrhoea, nausea, vomiting and epigastric pain (§4.8)
  • Uncommon: skin rash (§4.8)
  • Rare: liver damage (§4.8)
  • Very rare: calcium oxalate kidney stones (§4.8)
  • Frequency not known: local oesophagitis (capsule stuck in the throat) in patients who took the medicine without liquid before going to bed (§4.8)

Interactions

  • None known (SPC §4.5)

Monitoring

  • Ensure a sufficient liquid intake during treatment to maintain an adequate level of diuresis (calcium oxalate stone risk) (§4.4)
  • Watch for symptoms suggesting liver damage and discontinue if they occur (§4.4)
  • Swallow each capsule whole with at least one glass of water during meals; avoid taking it without liquid at bedtime (oesophagitis risk) (§4.2, §4.4)

Clinical monograph

How it works

It antagonises 5-HT2 receptors, which is thought to improve muscle metabolism and reduce vasoconstriction in ischaemic tissue.

Prescribing in practice

  • Capsules should be swallowed whole with plenty of fluid while sitting or standing to reduce the risk of oesophageal irritation and stricture.
  • It is an option for patients whose claudication limits lifestyle despite supervised exercise, and treatment should be reviewed for benefit after an adequate trial.
  • Hepatic and renal disorders have rarely been reported, so use with caution and stop if liver dysfunction occurs.

Monitoring

Review for symptomatic improvement after a defined trial period and discontinue if there is no meaningful benefit.

Counselling the patient

  • Swallow the capsules whole with a full glass of water and do not take them lying down.
  • Continue your exercise programme and address vascular risk factors such as smoking.
  • Report if your walking distance does not improve so treatment can be reassessed.

Evidence & guidelines

NICE identifies naftidrofuryl oxalate as the preferred drug option for intermittent claudication when exercise has not led to satisfactory improvement and surgery is not being considered.

Reference: NICE TA223 (Naftidrofuryl for PAD); Cochrane Review: Oral Vasodilators for PAD; ESVS PAD Guidelines 2017; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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