Dementa 5 mg

Description

Indications Dementa is prescribed for the treatment of all forms of dementia associated with Alzheimer’s disease. It may also be used for other types of dementia as recommended by a registered physician.

Pharmacology Alzheimer’s disease has been linked to persistent activation of N-methyl-D-aspartate (NMDA) receptors in the central nervous system by the excitatory amino acid glutamate. Memantine is believed to exert its therapeutic effects by acting as a low-to-moderate affinity uncompetitive NMDA receptor antagonist, binding selectively to NMDA receptor-operated cation channels.

Following oral administration, Memantine is well absorbed, with peak plasma concentrations reached within 3-7 hours. Food does not influence its absorption. The drug has a mean volume of distribution of 9-11 L/kg and a low plasma protein binding of approximately 45%. Memantine undergoes partial hepatic metabolism, with about 48% of the administered dose excreted unchanged in urine. The remaining portion is metabolized into three primary polar metabolites—N-glucuronide conjugate, 6-hydroxy Memantine, and 1-nitroso-deaminated Memantine—which have minimal NMDA receptor antagonistic activity. In total, 74% of the administered dose is excreted as the parent drug and its conjugate. The CYP-450 enzyme system does not significantly contribute to Memantine metabolism. The terminal elimination half-life of Memantine is approximately 60-80 hours.

Dosage & Administration The recommended maintenance dose of Memantine for adults and elderly patients is 20 mg per day. To minimize potential side effects, the dosage should be gradually increased over three weeks, following the schedule below:

• Week 1: Morning – 5 mg (1 tablet), Night – No dose
• Week 2: Morning – 5 mg (1 tablet), Night – 5 mg (1 tablet)
• Week 3: Morning – 10 mg (2 tablets), Night – 5 mg (1 tablet)
• Week 4 and onward: Morning – 10 mg (2 tablets), Night – 10 mg (2 tablets)

Missed Dose: If a dose is missed, take the next scheduled dose as usual. Do not double the dose to compensate for the missed one.

Renal Impairment:

• Moderate impairment (creatinine clearance 30-49 ml/min): Initial dose of 10 mg/day. If well tolerated after at least seven days, the dose may be increased to 20 mg/day following the standard titration schedule.
• Severe impairment (creatinine clearance 5-29 ml/min): A daily dose of 10 mg is recommended.

Hepatic Impairment:

• Mild to moderate impairment: No dosage adjustment required.
• Severe impairment: Use of Memantine is not recommended.

Pediatric Use: Memantine is not recommended for children under 18 years due to insufficient safety and efficacy data.

Drug Interactions Memantine’s mechanism of action suggests potential interactions with certain medications:

• May enhance the effects of L-dopa, dopaminergic agonists, and anticholinergics.
• May reduce the effects of barbiturates and neuroleptics.
• May modify the effects of dantrolene and baclofen, requiring dose adjustments.
• Should not be used with amantadine, ketamine, dextromethorphan, phenytoin, cimetidine, ranitidine, procainamide, quinidine, quinine, or nicotine.

Contraindications Memantine Hydrochloride is contraindicated in individuals with known hypersensitivity to Memantine Hydrochloride or any of its excipients.

Side Effects Common side effects (reported in ≤2% of cases) include hallucinations, confusion, dizziness, headache, and fatigue. Other possible effects include anxiety, increased muscle tone (hypertonus), vomiting, urinary tract infections, and increased libido. Patients with a history of epilepsy may have a slightly higher risk of seizures.

Pregnancy & Lactation

• Pregnancy: Classified as Category B. While no well-controlled studies have been conducted in pregnant women, Memantine should only be used if the benefits outweigh potential risks to the fetus.
• Lactation: It is unknown whether Memantine is excreted in breast milk. Caution is advised if administered to breastfeeding mothers.

Precautions & Warnings

• Caregivers should follow the recommended dosing schedule, particularly for dose escalation (minimum one-week intervals between increases).
• Patients with kidney dysfunction should have their renal function regularly monitored.
• Seizures: Although Memantine has not been extensively studied in seizure-prone individuals, clinical trials indicate that seizure occurrence was 0.2% in treated patients versus 0.5% in placebo groups.
• Carcinogenicity & Fertility: Studies indicate no significant risk of carcinogenesis, mutagenesis, or impaired fertility.
• Driving & Machinery Operation: Memantine may impair reaction time, making activities such as driving and machinery operation unsafe.

Therapeutic Class Drugs for Dementia

Storage Conditions Store in a cool, dry place away from light. Keep out of reach of children.