Ebixa

Ebixa is the original brand of memantine, made by Lundbeck. Memantine is classed as an NMDA receptor antagonist: it occupies the receptor channel that the messenger chemical glutamate uses, damping down the abnormally high background activity thought to occur in Alzheimer's disease while still allowing normal signals through. Its UK marketing authorisation covers only adults in whom Alzheimer's disease has progressed to a moderate or severe stage. It is a symptomatic treatment – the underlying illness continues – but it may help some people with memory, concentration, daily tasks and behaviour for a time. Because the person being treated may struggle to manage medicines, the SmPC expects a carer to oversee the daily dose.

Two tablet strengths, 5 mg and 10 mg, are offered in quantities of 30, 60, 90 or 180, sourced as an imported product. On the UK market Lundbeck supplies Ebixa as 10 mg and 20 mg film-coated tablets, a treatment initiation pack and a pump-dose oral solution, and memantine is also sold under its generic name. The medicine is prescription-only in the UK. Having both lower strengths makes it straightforward to follow the weekly build-up, though the daily total still has to stay within the licensed range.

Doses go up gradually to limit side effects. Days 1–7: 5 mg once daily. Days 8–14: 10 mg once daily. Days 15–21: 15 mg once daily. From day 22: 20 mg once daily, which is the maintenance dose and also the upper limit, so combining tablets to go beyond 20 mg is not appropriate. The tablet is swallowed at about the same time every day, before, with or after a meal. The prescriber, ideally one experienced in diagnosing and treating Alzheimer's dementia, looks at how well the medicine is working and being tolerated within roughly three months, and continues to reassess it at intervals.

Memantine leaves the body mainly through the kidneys, so kidney function guides the dose. A creatinine clearance of 50–80 ml/min needs no change. Between 30 and 49 ml/min the daily dose should be 10 mg, and it can go up to 20 mg using the usual steps if this has been well tolerated for at least a week. Below 30 ml/min, down to 5 ml/min, 10 mg daily is recommended. No change is needed for mild or moderate liver problems, but severe hepatic impairment is not a recommended setting for Ebixa. Children and teenagers are outside the licence.

The medicine must not be used by anyone allergic to memantine or the tablet ingredients. Close supervision is needed for people with epilepsy, those who have had a recent myocardial infarction, and those with heart failure or high blood pressure that is not under control. Anything that makes the urine more alkaline, including a drastic switch to a vegetarian diet, large amounts of antacids, renal tubular acidosis or a Proteus urinary infection, can let memantine build up. Other NMDA antagonists – amantadine, ketamine and dextromethorphan – are best avoided because of a risk of psychotic reactions. Ebixa may boost levodopa, dopamine agonists and anticholinergic drugs, reduce the effect of barbiturates and neuroleptics, and change how baclofen and dantrolene act; prothrombin time or INR monitoring is advisable with warfarin. In pregnancy it is used only if clearly needed, and women taking it should not breastfeed.

In clinical trials side effects were usually mild to moderate. Commonly reported ones are drowsiness, dizziness, headache, constipation, breathlessness, high blood pressure, poor balance, raised liver enzymes and allergic-type reactions. Confusion, hallucinations, sickness, fatigue, abnormal gait, fungal infection, venous thrombosis and worsening heart failure are uncommon, and fits are rare. As the medicine may cause dizziness or drowsiness, extra care is needed with driving or machinery. The decision to prescribe Ebixa, and to continue it, rests with the doctor.