Treatment of adult patients with moderate to severe Alzheimer's disease.

Treatment should be initiated and supervised by a physician experienced in the diagnosis and
treatment of Alzheimer's dementia.

Posology

Therapy should only be started if a caregiver is available who will regularly monitor the intake of the medicinal product by the patient. Diagnosis should be made according to current guidelines. The tolerance and dosing of Memantine should be reassessed on a regular basis, preferably within three months after start of treatment. Thereafter, the clinical benefit of Memantine and the patient's tolerance of treatment should be reassessed on a r egular basis according to current clinical guidelines. Maintenance treatment can be continued for as long as a therapeutic benefit is favorable and the patient tolerates treatment with Memantine. Discontinuation of Memantine should be considered when evidence of a therapeutic effect is no l onger present or if the patient does not tolerate treatment.

Dosage

The recommended starting dose is 5 mg per day, which is stepwise increased over the first 4 weeks of treatment reaching the recommended maintenance dose as follows:

The usual starting dose is half a tablet once a day (1x 5 mg) for the first week. This is increased to one tablet once a day (1x 10 mg) in the second week and to 1 and a half tablets once a day in the third week. From the fourth week on, the usual dose is 2 tablets once a day (1x 20 mg).

Maintenance dose

The recommended maintenance dose is 20 mg per day.

Elderly

On the basis of the clinical studies, the recommended dose for patients over the age of 65 years is 20 mg per day (one 20 mg film-coated tablet/two 10 mg film-coated tablets) as described above.

Renal impairment

In patients with mildly impaired renal function (creatinine clearance 50 – 80 ml/min) no dos e adjustment is required. In patients with moderate renal impairment (creatinine clearance 30 – 49 ml/min) daily dose should be 10 mg (one 10 mg film-coated tablet) per day. If tolerated well after  at least 7 days of treatment, the dose could be increased up to 20 mg/day according to standard titration scheme. In patients with severe renal impairment (creatinine clearance 5 – 29 ml/min) daily dose should be 10 mg (one 10 mg film-coated tablet) per day.

Hepatic impairment

In patients with mild or moderate hepatic impaired function (Child-Pugh A and Child-Pugh B), no dose adjustment is needed. No data on the use of Memantine in patients with severe hepatic impairment are available. Administration of Memaxia is not recommended in patients with severe hepatic impairment.

Paediatric population

No data available.

Method of administration

Memaxia tablets should be administered orally once a day and should be taken at the same time every day. The film-coated tablets can be taken with or without food.

Caution is recommended in patients with epilepsy, former history of convulsions or patients with predisposing factors for epilepsy.

Concomitant use of N-methyl-D-aspartate (NMDA)-antagonists such as amantadine, ketamine or dextromethorphan should be avoided. These compounds act at the same receptor system as memantine, and therefore adverse reactions (mainly central nervous system (CNS)-related) may be more frequent or more pronounced.

Some factors that may raise urine pH may necessitate careful monitoring of the patient. These factors include drastic changes in diet, e.g. from a carnivore to a v egetarian diet, or a m assive ingestion of alkalising gastric buffers. Also, urine pH may be elevated by states of renal tubulary acidosis (RTA) or severe infections of the urinary tract with Proteus bacteria.

In most clinical trials, patients with recent myocardial infarction, uncompensated congestive heart failure (NYHA III-IV), or uncontrolled hypertension were excluded. As a consequence, only limited data are available and patients with these conditions should be closely supervised.

Excipients: The oral solution contains sorbitol. Patients with rare hereditary problems of fructose intolerance should not take this medicine.

Due to the pharmacological effects and the mechanism of action of Memantine the following interactions may occur:

•  The mode of action suggests that the effects of L-dopa, dopaminergic agonists, and anticholinergics may be enhanced by concomitant treatment with NMDA-antagonists such as memantine. The effects of barbiturates and neuroleptics may be reduced. Concomitant administration of memantine with the antispasmodic agents, dantrolene or baclofen, can modify their effects and a dose adjustment may be necessary.

•  Concomitant use of memantine and amantadine should be avoided, owing to the risk of pharmacotoxic psychosis. Both compounds are chemically related NMDA-antagonists. The same may be true for ketamine and dextromethorphan. There is one published case report on a possible risk also for the combination of memantine and phenytoin.

• Other active substances such as cimetidine, ranitidine, procainamide, quinidine, quinine and nicotine that use the same renal cationic transport system as amantadine may also possibly interact with memantine leading to a potential risk of increased plasma levels.

•  There may be a possibility of reduced serum level of hydrochlorothiazide (HCT) when memantine is co-administered with HCT or any combination with HCT.

• In post-marketing experience, isolated cases with international normalized ratio (INR) increases have been reported in patients concomitantly treated with warfarin. Although no causal relationship has been established, close monitoring of prothrombin time or INR is advisable for patients concomitantly treated with oral anticoagulants.

In single-dose pharmacokinetic (PK) studies in young healthy subjects, no r elevant active substance-active substance interaction of memantine with glyburide/metformin or donepezil was observed.

In a clinical study in young healthy subjects, no r elevant effect of memantine on the pharmacokinetics of galantamine was observed.

Memantine did not inhibit CYP 1A2, 2A6, 2C9, 2D6, 2E1, 3A, flavin containing monooxygenase, epoxide hydrolase or sulphation in vitro.

Pregnancy Category B
Studies in pregnant women, however, have not shown that Memantine increases the risk of
abnormalities when administered during the first {second, third, or all} trimester(s) of pregnancy.
Despite the animal findings, it would appear that the possibility of fetal harm is remote, if the drug
is used during pregnancy. Nevertheless, because the studies in humans cannot rule out the
possibility of harm, Memantine should be used during pregnancy only if clearly needed”.
Pregnancy: There are no or limited amount of data from the use of Memantine in pregnant women.
Animal studies indicate a potential for reducing intrauterine growth at exposure levels, which are
identical or slightly higher than at human exposure. The potential risk for humans is unknown.
Memantine should not be used during pregnancy unless clearly necessary.
Breast-feeding: It is not known whether Memantine is excreted in human breast milk but, taking
into consideration the lipophilicity of the substance, this probably occurs. Women taking
Memantine should not breast-feed.
Fertility: No adverse reactions of Memantine were noted on male and female fertility.

Moderate to severe Alzheimer's disease usually causes impairment of driving performance and compromises the ability to use machinery. Furthermore, Memaxia has minor to moderate influence on the ability to drive and use machines such that outpatients should be warned to take special care.

Summary of the safety profile
In clinical trials in mild to severe dementia, involving 1,784 patients treated with Memantine and
1,595 patients treated with placebo, the overall incidence rate of adverse reactions with Memantine
did not differ from those with placebo; the adverse reactions were usually mild to moderate in
severity. The most frequently occurring adverse reactions with a higher incidence in the Memantine
group than in the placebo group were dizziness (6.3% vs 5.6%, respectively), headache (5.2% vs
3.9%), constipation (4.6% vs 2.6%), somnolence (3.4% vs 2.2%) and hypertension (4.1% vs 2.8%).
Tabulated list of adverse reactions
The following Adverse Reactions listed in the Table below have been accumulated in clinical
studies with Memaxia and since its introduction in the market.
Adverse reactions are ranked according to system organ class, using the following convention: very
common (≥1/10), common (≥1/100 to < 1/10), uncommon (≥ 1/1,000 to < 1/100), rare (≥1/10,000
to < 1/1,000), very rare (< 1/10,000), not known (cannot be estimated from the available data).
Within each frequency grouping, undesirable effects are presented in order of decreasing
seriousness.

1 Hallucinations have mainly been observed in patients with severe Alzheimer's disease.

2 Isolated cases reported in post-marketing experience.

Alzheimer's disease has been associated with depression, suicidal ideation and suicide. In post- marketing experience these reactions have been reported in patients treated with Memantine.

To report any side effect(s):

•   Saudi Arabia:

The National Pharmacovigilance and Drug Safety Centre (NPC)

·         Fax: +966-11-205-7662

·         Call NPC at +966-11-2038222, Exts: 2317-2356-2353-2354-2334-2340.

·         Toll free phone: 8002490000

·         E-mail: npc.drug@sfda.gov.sa

·         Website: www.sfda.gov.sa/npc

Only limited experience with overdose is available from clinical studies and post-marketing experience.

Symptoms

Relative large overdoses (200 mg and 105 mg/day for 3 days, respectively) have been associated with either only symptoms of tiredness, weakness and/or diarrhoea or no symptoms. In the overdose cases below 140 m g or unknown dose the patients revealed symptoms from central nervous system (confusion, drowsiness, somnolence, vertigo, agitation, aggression, hallucination, and gait disturbance) and/or of gastrointestinal origin (vomiting and diarrhoea).

In the most extreme case of overdose, the patient survived the oral intake of a total of 2000 mg memantine with effects on the central nervous system (coma for 10 days, and later diplopia and agitation). The patient received symptomatic treatment and plasmapheresis. The patient recovered without permanent sequelae.

In another case of a large overdose, the patient also survived and recovered. The patient had received 400 mg memantine orally. The patient experienced central nervous system symptoms such as restlessness, psychosis, visual hallucinations, proconvulsiveness, somnolence, stupor, and unconsciousness.

Treatment

In the event of overdose, treatment should be symptomatic. No specific antidote for intoxication or overdose is available. Standard clinical procedures to remove active substance material, e.g. gastric lavage, carbo medicinalis (interruption of potential entero-hepatic recirculation), acidification of urine, forced diuresis should be used as appropriate.

In case of signs and symptoms of general central nervous system (CNS) overstimulation, careful symptomatic clinical treatment should be considered.

Pharmacotherapeutic group: Psychoanaleptics. Other Anti-dementia drugs, ATC code: N06DX01. There is increasing evidence that malfunctioning of glutamatergic neurotransmission, in particular at NMDA-receptors, contributes to both expression of symptoms and disease progression in neurodegenerative dementia.

Memantine is a voltage-dependent, moderate-affinity uncompetitive NMDA-receptor antagonist. It modulates the effects of pathologically elevated tonic levels of glutamate that may lead to neuronal dysfunction.

Clinical studies
A pivotal monotherapy study in a population of patients suffering from moderate to severe
Alzheimer's disease (mini mental state examination (MMSE) total scores at baseline of 3 - 14)
included a total of 252 outpatients. The study showed beneficial effects of memantine treatment in
comparison to placebo at 6 months (observed cases analysis for the clinician´s interview based
impression of change (CIBIC-plus): p=0.025; Alzheimer's disease cooperative study – activities of
daily living (ADCS-ADLsev): p=0.003; severe impairment battery (SIB): p=0.002).
A pivotal monotherapy study of memantine in the treatment of mild to moderate Alzheimer's
disease (MMSE total scores at baseline of 10 to 22) included 403 patients. Memantine-treated
patients showed a statistically significantly better effect than placebo-treated patients on the
primary endpoints: Alzheimer's disease assessment scale (ADAS-cog) (p=0.003) and CIBIC-plus
(p=0.004) at week 24 (last observation carried forward (LOCF)). In another monotherapy study in
mild to moderate Alzheimer's disease a total of 470 patients (MMSE total scores at baseline of 11-
23) were randomised. In the prospectively defined primary analysis statistical significance was not
reached at the primary efficacy endpoint at week 24.
A meta-analysis of patients with moderate to severe Alzheimer's disease (MMSE total scores < 20)
from the six phase III, placebo-controlled, 6-month studies (including monotherapy studies and
studies with patients on a stable dose of acetylcholinesterase inhibitors) showed that there was a
statistically significant effect in favour of Memantine treatment for the cognitive, global, and
functional domains. When patients were identified with concurrent worsening in all three domains,
results showed a statistically significant effect of Memantine in preventing worsening, as twice as
many placebo-treated patients as Memantine-treated patients showed worsening in all three
domains (21% vs. 11%, p<0.0001).

Absorption

Memantine has an absolute bioavailability of approximately 100%. T_max is between 3 and 8 hours. There is no indication that food influences the absorption of Memantine.

Distribution

Daily doses of 20 mg lead to steady-state plasma concentrations of Memantine ranging from 70 to 150 ng/ml (0.5 - 1 µmol) with large interindividual variations. When daily doses of 5 t o 30 mg were administered, a mean cerebrospinal fluid (CSF)/serum ratio of 0.52 was calculated. The volume of distribution is around 10 l/kg. About 45% of Memantine is bound to plasma-proteins.

Biotransformation

In man, about 80% of the circulating Memantine-related material is present as the parent compound. Main human metabolites are N-3,5-dimethyl-gludantan, the isomeric mixture of 4- and 6-hydroxy-memantine, and 1-nitroso-3,5-dimethyl-adamantane. None of these metabolites exhibit NMDA-antagonistic activity. No cytochrome P 450 catalysed metabolism has been detected in vitro.

In a study using orally administered ¹⁴C-memantine, a mean of 84% of the dose was recovered within 20 days, more than 99% being excreted renally.

Elimination

Memantine is eliminated in a monoexponential manner with a terminal t_½ of 60 to 100 hours. In volunteers with normal kidney function, total clearance (Cl_tot) amounts to 170 ml/min/1.73 m² and part of total renal clearance is achieved by tubular secretion.

Renal handling also involves tubular reabsorption, probably mediated by cation transport proteins. The renal elimination rate of memantine under alkaline urine conditions may be reduced by a factor of 7 to 9 (see section 4.4). Alkalisation of urine may result from drastic changes in diet, e.g. from a carnivore to a vegetarian diet, or from the massive ingestion of alkalising gastric buffers.

Linearity

Studies in volunteers have demonstrated linear pharmacokinetics in the dose range of 10 to 40 mg. Pharmacokinetic/pharmacodynamic relationship

At a dose of Memantine of 20 mg per day the CSF levels match the k_i-value (k_i = inhibition constant) of Memantine, which is 0.5 µmol in human frontal cortex.

In short term studies in rats, Memantine like other NMDA-antagonists have induced neuronal vacuolisation and necrosis (Olney lesions) only after doses leading to very high peak serum concentrations. Ataxia and other preclinical signs have preceded the vacuolisation and necrosis. As the effects have neither been observed in long term studies in rodents nor in non-rodents, the clinical relevance of these findings is unknown.

Ocular changes were inconsistently observed in repeat dose toxicity studies in rodents and dogs, but not in monkeys. Specific ophthalmoscopic examinations in clinical studies with Memantine did not disclose any ocular changes.

Phospholipidosis in pulmonary macrophages due to accumulation of Memantine in lysosomes was observed in rodents. This effect is known from other active substances with cationic amphiphilic properties. There is a possible relationship between this accumulation and the vacuolisation observed in lungs. This effect was only observed at high doses in rodents. The clinical relevance of these findings is unknown.

No genotoxicity has been observed following testing of Memantine in standard assays. There was no evidence of any carcinogenicity in lifelong studies in mice and rats. Memantine was not teratogenic in rats and rabbits, even at maternally toxic doses, and no adverse effects of Memantine were noted on fertility. In rats, foetal growth reduction was noted at exposure levels, which are identical or slightly higher than at human exposure.

Core tablet content:

Microcrystalline cellulose, Croscarmellose Sodium, Colloidal Silicon dioxide, Magnesium Stearate.

Coating content:

Opadry OYB (which contains polyvinyl alcohol, titanium dioxide, talc, soy lecithin & Xanthan gum) and Iron oxide yellow.

Not applicable.

Do not store above 30 ºC.

Memaxia 10 mg Film Coated Tablets are packed as 10 Tablets in Aluminum-PVC/PVDC blister containing 30 (3x10) film coated tablets in outer carton with Patient Information Leaflet.

No special requirements.