Milnacipran Hydrochloride for Fibromyalgia

Milnacipran is a dual reuptake inhibitor of noradrenaline and serotonin. It is indicated for the treatment of fibromyalgia after the failure of standard treatment options. Milnacipran is the first drug approved in Australia by the Therapeutic Goods Administration (TGA) for fibromyalgia.

Fibromyalgia is a chronic pain condition often developing during middle adulthood. It affects between 2-5% of the population and is more prevalent in women. Fibromyalgia is characterised by widespread pain and tenderness in the body. Other symptoms include tiredness, sleep disturbances, stiffness, and fatigue. The cause of fibromyalgia is unknown. However, the pain is attributed to changes in the biochemical functions of the pain system rather than a defect in the musculoskeletal system.

Physical activity and psychological therapies are the first-line treatment options for fibromyalgia, followed by pharmacological approaches if responses are inadequate. Current pharmacological treatment options include simple analgesia and the off-label use of pregabalin and several antidepressants such as amitriptyline or duloxetine.

The starting dose for milnacipran is 25mg daily and can be titrated to 50mg twice a day. Doses up to 100mg twice a day may be prescribed, depending on efficacy and tolerability. The main adverse effects leading to discontinuation of therapy include nausea, vomiting, headache, constipation, hyperhidrosis, and insomnia. These adverse effects appear to be dose-related. Therefore, dose reduction may be considered before discontinuation is recommended. The use of milnacipran is contraindicated in patients with severe cardiac function impairment, very high risk of serious cardiac arrhythmias, uncontrolled hypertension, severe coronary heart disease, and uncontrolled narrow-angle glaucoma. Concurrent treatment with monoamine oxidase (MAO) inhibitors, selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline reuptake inhibitors (SNRIs), tramadol, tricyclic antidepressants, adrenaline, and noradrenaline is also contraindicated with milnacipran.