Namenda 10 mg Tablets

Brand Name

This therapeutic agent is marketed under the trade name Namenda, a designation widely acknowledged in the management of cognitive disorders.

International Non-Proprietary Name

The active substance is identified globally as memantine, following the standardized nomenclature for pharmaceutical compounds.

Form of Release

The drug is available in multiple oral forms to accommodate varying patient preferences. It comes as immediate-release tablets in strengths of 5 milligrams and 10 milligrams. An extended-release capsule version is offered in 7-milligram, 14-milligram, 21-milligram, and 28-milligram doses for once-daily administration. Additionally, an oral solution at 2 milligrams per milliliter provides an option for those needing flexible dosing or easier intake.

Composition

The primary ingredient is memantine hydrochloride, which drives its effects through receptor modulation. Immediate-release tablets include excipients such as microcrystalline cellulose, lactose monohydrate, magnesium stearate, and croscarmellose sodium to ensure stability and disintegration. Extended-release capsules feature a controlled-release matrix with components like hypromellose and ethylcellulose, alongside similar fillers. The oral solution contains sorbitol, sodium citrate, and purified water, with a flavoring agent to enhance palatability.

Pharmacologic Properties

Pharmacodynamics

This medication functions as an uncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptors in the brain. By binding to these receptors, it regulates glutamate activity, a neurotransmitter linked to neuronal excitability and memory processes. Excessive glutamate can lead to excitotoxicity, damaging nerve cells, particularly in degenerative conditions. The drug’s moderate affinity allows it to block pathological overstimulation while preserving normal synaptic transmission, offering a unique neuroprotective approach.

Clinical studies show it stabilizes cognitive function and slows symptom worsening in affected patients. Its action targets areas like the cortex and hippocampus, reducing neuronal stress without broadly disrupting brain activity. This mechanism supports its use in managing advanced cognitive decline, providing measurable benefits in daily living and mental clarity.

Pharmacokinetics

After oral administration, the medication absorbs well from the gastrointestinal tract, reaching peak plasma levels in 3 to 8 hours for immediate-release forms and 9 to 12 hours for extended-release versions. Food does not significantly affect absorption, allowing flexible timing. Bioavailability is nearly 100 percent, reflecting minimal first-pass metabolism and efficient uptake.

The substance distributes extensively, with a volume of distribution around 9 to 11 liters per kilogram, indicating broad tissue penetration, including the central nervous system. It binds to plasma proteins at about 45 percent, leaving a substantial portion free to act. Metabolism is limited, with the liver converting only a small fraction into three inactive metabolites via cytochrome P450-independent pathways. The half-life ranges from 60 to 100 hours, supporting once-daily dosing for sustained effects.

Excretion occurs predominantly through urine, with over 80 percent eliminated unchanged. Renal clearance is significant, influenced by urine pH and kidney function, requiring adjustments in certain cases. A minor amount exits via feces, but the kidneys remain the primary elimination route.

Indications for Use

Conditions and Disorders

The medication is prescribed for moderate to severe Alzheimer’s disease, a progressive neurodegenerative disorder impairing memory and cognition. It helps manage symptoms like confusion, disorientation, and difficulty with daily tasks, supporting patients in later stages where other treatments may lose efficacy. By modulating glutamate activity, it offers a complementary approach to existing therapies.

Namenda is particularly valuable for advanced cases, improving behavioral stability and functional capacity. While its primary approval centers on Alzheimer’s, some clinicians explore its potential in other dementias or neurological conditions, though such applications lack broad validation and remain investigational.

Contraindications

Conditions Prohibiting Use

The drug is contraindicated in patients with hypersensitivity to memantine hydrochloride or related compounds, as reactions could range from mild rashes to severe allergic responses. Severe renal impairment, with creatinine clearance below 5 milliliters per minute, precludes its use due to risks of accumulation and toxicity.

It should not be administered to individuals with conditions requiring highly acidic urine, such as renal tubular acidosis, as this could alter excretion and elevate plasma levels. Use is also restricted in patients with recent myocardial infarction or uncontrolled congestive heart failure, where its effects on the central nervous system might complicate cardiovascular stability.

Method of Administration and Dosage

Administration Guidelines

The medication is taken orally, with or without food, providing flexibility in timing. Immediate-release tablets are typically dosed twice daily, swallowed whole with water. Extended-release capsules are taken once daily, preferably in the morning, also with water. The oral solution requires precise measurement with a provided device and can be mixed with a small amount of water or juice for easier consumption.

Dosage for Adults and Children

For adults with moderate to severe Alzheimer’s, immediate-release therapy starts at 5 milligrams daily, increasing by 5 milligrams weekly to a target of 10 milligrams twice daily. Extended-release begins at 7 milligrams daily, escalating weekly by 7 milligrams to a maximum of 28 milligrams daily. Pediatric use is not approved, as safety and efficacy in children have not been established, limiting its application to adults.

Dose Adjustments for Specific Conditions

In moderate renal impairment (creatinine clearance 30 to 49 milliliters per minute), the maximum dose is typically 5 milligrams twice daily for immediate-release or 14 milligrams daily for extended-release. Severe renal impairment (5 to 29 milliliters per minute) requires further reduction to 5 milligrams daily or 7 milligrams daily, respectively. Hepatic impairment does not usually require adjustment, as metabolism is minimal, but caution is advised in severe cases.

Side Effects

Potential Adverse Reactions

Common effects include dizziness, headache, and constipation, often mild and related to central nervous system adjustment. Fatigue and drowsiness may occur, particularly during dose escalation, typically resolving with time. Some patients report mild confusion or agitation, which can overlap with disease symptoms.

Less frequent reactions involve hypertension or balance issues, potentially increasing fall risk in vulnerable individuals. Rarely, hallucinations, seizures, or urinary incontinence emerge, especially at higher doses or in advanced disease stages. Severe allergic responses or significant behavioral changes warrant immediate medical attention.

Overdose

Symptoms of Excessive Intake

Excessive dosing may lead to restlessness, agitation, and elevated blood pressure, reflecting central nervous system overstimulation. Severe cases can progress to stupor, psychosis, or coma, with slowed breathing or heart irregularities posing critical risks. Symptoms vary widely depending on the amount ingested and patient factors.

First Aid Measures

Cease administration and seek emergency care promptly. Activated charcoal may reduce absorption if given within an hour, provided the patient is alert. No specific antidote exists, so treatment focuses on supportive care, such as monitoring vital signs and managing symptoms like hypertension or sedation. Professional oversight is essential to stabilize the patient.

Drug Interactions

Effects on Other Medications

The medication can enhance the effects of other NMDA antagonists, like amantadine, increasing risks of neurological side effects. It may alter the clearance of drugs excreted via renal tubular secretion, such as hydrochlorothiazide, by competing for the same pathways. Agents that alkalinize urine, like sodium bicarbonate, could reduce its excretion, raising plasma levels and potential toxicity.

Namenda may interact with dopaminergic drugs, such as levodopa, amplifying motor effects or agitation in some cases. Caution is needed with central nervous system depressants, like benzodiazepines, as combined sedation could intensify drowsiness or confusion.

Compatibility with Alcohol and Food

Alcohol does not directly affect its pharmacokinetics but may exacerbate dizziness or fatigue, so moderation is recommended. Food has no significant impact on absorption, allowing administration with meals if preferred for convenience or tolerability. No specific dietary restrictions apply.

Special Precautions

Use During Pregnancy and Breastfeeding

Limited data exist on pregnancy use, with no clear evidence of harm or safety in humans. Animal studies show no major fetal risks, but the drug should only be used if benefits outweigh potential uncertainties, under medical supervision. It may pass into breast milk in small amounts, so nursing mothers should consult a physician, possibly pausing lactation during treatment.

Impact on Driving and Machinery Operation

The medication may cause dizziness, drowsiness, or balance issues, particularly during initial use or dose increases. Patients should assess their response before driving or operating equipment, avoiding these activities if impaired. Caregivers may need to monitor those with advanced disease for additional safety.

Considerations for Elderly and Pediatric Patients

Elderly patients, the primary users due to Alzheimer’s prevalence, generally tolerate it well, though reduced kidney function may require dose adjustments in moderate to severe impairment. Namenda is not approved for children, as its role in pediatric conditions lacks evidence, restricting use to adults.