memantine hydrochloride: clinical use

Prescribing considerations

• Treatment should be initiated and supervised by a clinician experienced in diagnosing and treating Alzheimer’s dementia.
• Confirm that a caregiver or suitable support is available to monitor medicine-taking.
• Assess renal and hepatic function because impaired clearance can alter exposure; use in severe hepatic impairment is not recommended.
• Use caution with epilepsy or seizure risk, recent myocardial infarction, uncompensated heart failure or uncontrolled hypertension.
• Review significant dietary change, renal tubular acidosis, severe Proteus urinary infection or heavy use of alkalising gastric products because raised urine pH can reduce elimination.

Contraindications and cautions

• Hypersensitivity to memantine or any product excipient.
• The selected sorbitol-containing oral solution is unsuitable in hereditary fructose intolerance.
• Some orodispersible products contain lactose and aspartame; check suitability in relevant inherited sugar disorders and phenylketonuria.

Monitoring

• Reassess clinical benefit, tolerability and adherence early after initiation and regularly thereafter.
• Monitor renal function when clinically indicated, particularly after intercurrent illness or major dietary change.
• Closely supervise patients with significant cardiovascular disease or seizure risk.
• Monitor INR or prothrombin time more closely with oral anticoagulants such as warfarin.
• Review dizziness, gait, cognition, behaviour, blood pressure and suspected hepatic adverse effects.

Clinical pharmacology

Memantine is a voltage-dependent, moderate-affinity, uncompetitive NMDA-receptor antagonist. It is well absorbed, undergoes little CYP-mediated metabolism and is eliminated predominantly through the kidneys; alkaline urine substantially slows renal elimination.

Formulation and product differences

• Orodispersible tablets disintegrate on the tongue and can be swallowed with or without water.
• Film-coated tablets are swallowed; the selected initiation pack contains different tablet strengths.
• The pump oral solution must be dispensed onto a spoon or into water rather than directly into the mouth, and the bottle should be kept upright.
• Excipients differ: the selected oral solution contains sorbitol, while Mentino orodispersible tablets contain lactose and aspartame. Check the exact product before prescribing or supplying.

Dispersible tablet

Route: Oral

Strengths: 5 mg, 5 mg + 10 mg + 15 mg + 20 mg, 10 mg, 15 mg, 20 mg