PHENTERMINE XR-WGR

What it is

PHENTERMINE XR-WGR contains phentermine as an ion-exchange resin complex, available in 15 mg, 30 mg and 40 mg modified release capsules. The ion-exchange resin releases phentermine in a continuous and controlled manner over a 10 to 14 hour period. Phentermine is a sympathomimetic amine with significant anorectic activity.

Approved indications

— Management of obesity as a short-term adjunct in a medically monitored comprehensive regimen of weight reduction based on exercise, diet and behaviour modification in obese patients with a body mass index of 30 kg/m² or greater. — Treatment in overweight patients with a lower BMI of 25 to 29.9 kg/m² which increases the risk of morbidity from a number of disorders.

Dosing overview

The recommended starting dose is 30 mg daily. Larger framed individuals may require 40 mg daily. The recommended maintenance dose, either continuous or intermittent, is 15 to 40 mg daily depending on responsiveness. One capsule is taken daily at breakfast, swallowed whole. Evening dosing should be avoided, as this agent may induce insomnia. Patients require medical review after a defined course of treatment, which should not exceed three months.

Key safety warnings

Serious regurgitate cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of fenfluramine or dexfenfluramine with phentermine for weight loss. There have been no reported cases to date of valvular heart disease occurring with the use of phentermine alone. The possibility of an association between primary pulmonary hypertension and the use of phentermine alone cannot be ruled out, with very rare cases of primary pulmonary hypertension reported in patients who have taken phentermine alone. The initial symptom of primary pulmonary hypertension is usually dyspnoea, with other early symptoms including angina pectoris, syncope, lower extremity oedema or unexplained onset or aggravation of diminished exercise tolerance. Under these circumstances, treatment should be immediately discontinued and the patient referred to a specialist unit for investigation. Cardiovascular and cerebrovascular events have rarely been reported, mainly in association with rapid weight loss, and weight loss should be gradual and controlled in obese patients undergoing treatment with PHENTERMINE XR-WGR.

Contraindications

PHENTERMINE XR-WGR is contraindicated in pulmonary artery hypertension; existing heart valve abnormalities or heart murmurs; moderate to severe arterial hypertension; cerebrovascular disease; severe cardiac disease including arrhythmias and advanced arteriosclerosis; known hypersensitivity to sympathomimetic drugs; hyperthyroidism; agitated states or a history of psychiatric illnesses including anorexia nervosa and depression; glaucoma; history of drug or alcohol abuse or dependence; and concomitant treatment with Monoamine Oxidase Inhibitors or within 14 days following their administration.

Regulatory history

PHENTERMINE XR-WGR was first registered on the Australian Register of Therapeutic Goods on 11 August 2021, with three registered strengths: 15 mg, 30 mg and 40 mg modified release capsules.