PEXSIG

What it is

Pexsig contains perhexiline maleate as the active ingredient. Each tablet contains perhexiline maleate 100 mg. The tablets are white to off-white and scored on one side. Perhexiline maleate is an anti-anginal agent.

Approved indications

— To reduce the frequency of moderate to severe attacks of angina pectoris due to coronary artery disease in patients who have not responded to other conventional therapy or in whom such therapy may be contra-indicated.

Dosing overview

Adults: commence therapy with 100 mg daily. Adjust progressively, up or down, at 2 to 4 weekly intervals based on the results of plasma level monitoring. It is generally advised not to administer more than 300 mg per day, in divided doses, but in certain cases it may be necessary to use 400 mg per day. The maintenance dose must be the minimum dose that is effective and well tolerated. Plasma perhexiline concentrations should be maintained between 0.15 and 0.60 μg/mL. Because of perhexiline's slow and variable clearance, the marked inter-subject variability in metabolism of the drug and the potential for serious toxicity, regular monitoring of plasma levels of perhexiline is essential commencing at the end of the first week of use.

Key safety warnings

Sensory, motor and autonomic neuropathy has been reported in several patients on long term therapy with perhexiline, and in some cases of motor nerve dysfunction, biopsies showed denervation atrophy and demyelinisation. Hepatotoxicity as manifested by an elevation in serum liver enzymes is a common adverse effect occurring during perhexiline therapy. Serum enzymes (SGPT, SGOT, ALP, LDH) should therefore be assessed prior to the commencement of treatment and at least every month thereafter. Pexsig should be administered with caution to patients with diabetes mellitus, as hypoglycaemia is most likely to occur in diabetic patients receiving insulin or sulphonylureas; in the majority of such patients, fasting blood sugar levels fall by approximately 30% over the first three days of therapy. Pexsig has an effect on the ventricular conduction systems that may also have the potential of producing or aggravating ventricular conduction disturbances. Approximately 65% of patients on perhexiline suffer adverse effects and in 7 to 8% of all patients receiving perhexiline, these are sufficiently severe to warrant discontinuing therapy.

Contraindications

Pexsig is not recommended in the presence of a history of porphyria, impaired hepatic or renal function, or known hypersensitivity to the drug. If facilities for determining plasma levels are not available, Pexsig should not be prescribed.

PBS listing

Pexsig is listed on the PBS as a tablet containing perhexiline maleate 100 mg with streamlined restriction, at an ex-manufacturer price of A$38.59.

Regulatory history

Pexsig was first registered on the ARTG on 11 April 1995.