Donepezil Rex (Donepezil 5mg) Tablets

Donepezil Rex general information

What is Donepezil Rex used for?

Donepezil Rex tablets 5mg are used to treat mild, moderate and severe Alzheimer's Disease, which is the most common form of dementia among older people.  Alzheimer's Disease is a progressive, irreversible, brain disease that leads to a gradual loss of cognitive function, which includes attention, thinking, reasoning, learning, language, and memory.  As the disease progresses, symptoms worsen resulting in memory loss, language problems, difficulty remembering new information, and unpredictable behaviour.  Personality changes eventually become apparent and the patient loses the ability to manage daily tasks.  Donepezil Rex tablets 5mg are also used to treat vascular dementia, which is brain damage caused by cerebrovascular disease, resulting in reduced blood flow to the brain and death of nerve cells in that part of the brain.  This can be caused by stroke or damage to the blood vessels due to high blood pressure, atherosclerosis (fatty deposits in the artery walls) or just wear and tear associated with aging.  Symptoms are similar to Alzheimer's Disease and include impaired ability to think and reason, confusion, memory loss and agitation and can develop suddenly if associated with a stroke.  Donepezil Rex tablets 5mg slow down the progression of Alzheimer's Disease and dementia to improve daily functioning, memory and clear thinking, but cannot prevent the loss of cognitive function, stop progression or cure the disease. 

How does Donepezil Rex work?

Donepezil Rex tablets 5mg contain donepezil a specific and reversible inhibitor of acetylcholinesterase that is used to treat Alzheimer's Disease.  Alzheimer's Disease is associated with the loss of cholinergic activity in the brain particularly the cerebral cortex, also known as the grey matter, which is the part of the brain that controls cognitive function.  This is due to the degeneration of nerve cells (neurones), particularly those that produce the neurotransmitter acetylcholine, which is a chemical that allows nerve cells to communicate.  Normally acetylcholine is continually released by neurones and then degraded by the enzyme cholinesterase to prevent it building up in the synapses, which is the gap between neurones.  In the brain of a person with Alzheimer's disease, two types of abnormal structure appear and these are associated with the degeneration and death of brain cells.   Beta-amyloid plaques are protein fragments that are generated by the destruction of amyloidogenic beta-amyloid-precursor protein (APP) and deposited between neurones where they accumulate.  APP is a protein normally found in the membrane of a wide variety of cells throughout the body and accumulates in neurone synapses.  It is thought to be involved in the regulation of normal growth and development of nerve cells, including synaptogenesis, which is the formation of synapses between nerve cells allowing them to communicate by transmission of neurotransmitters.  The other structure consists of tangles of twisted fibres of another protein called tau that builds up inside dying nerve cells.  Tau proteins are a normal component of cellular microtubules and concentrates in neural cells.  Increased enzyme activity that destroys tau protein structures is thought to result in the formation of tangled abnormal tau protein, that disrupts normal synaptic activity.  Plaques and tangles are thought to be responsible for damaging and killing nerve cells; followed by loss of connections between neurones in the brain, spreading from the cerebral cortex to other regions of the brain.  Loss of acetylcholine producing neurones contributes to symptoms of dementia.  Donepezil in Donepezil Rex tablets 5mg inhibits the action of cholinesterase, which slows down the degradation of acetylcholine released by acetylcholine-producing neurones that are still functional, and this increases levels of acetylcholine in the damaged areas of the brain.  It is also thought that inhibition of cholinesterase may slow the formation APP fragments and thereby production of amyloid plaques¹.  By enhancing the cholinergic activity in the brain, Donepezil Rex tablets 5mg help improve symptoms of dementia but cannot prevent its progression.

What does Donepezil Rex contain?

Donepezil Rex tablets 5mg contain the active ingredient donepezil, that is used to treat Alzheimer's Disease and vascular dementia.  They also contain colloidal silicon dioxide, croscarmellose sodium, lactose monohydrate, magnesium stearate, microcrystalline cellulose, Opadry yellow 04F52201, purified water, starch.

Treating dementia with Donepezil Rex

Donepezil Rex tablets 5mg contain donepezil a specific and reversible inhibitor of acetylcholinesterase that is used to treat Alzheimer's Disease and vascular dementia.  Alzheimer's Disease is a progressive, irreversible, brain disease due to degeneration and death of brain cells particularly the cerebral cortex which is the part of the brain that controls cognitive function.  As the disease progresses a gradual loss of cognitive function, causes impaired attention, thinking, reasoning, learning, language, and memory.  Vascular dementia is brain damage caused by cerebrovascular disease, resulting in reduced blood flow to the brain and death of the brain cells in that part of the brain.  This can be caused by stroke or damage to the blood vessels due to high blood pressure, atherosclerosis (fatty deposits in the artery walls) or just wear and tear associated with aging.  Symptoms of dementia are associated with death of nerve cells (neurones) that produce the neurotransmitter acetylcholine, which is continually released and then degraded by the enzyme cholinesterase to prevent it building up in the synapses, which is the gap between neurones.  Two types of abnormal structure have been identified in the brain of a person with Alzheimer's disease; these are beta-amyloid plaques and tangles of tau protein and they are thought to be responsible for damaging and killing nerve cells, followed by loss of connections between neurones in the brain, spreading from the cerebral cortex to other regions of the brain. Donepezil in Donepezil Rex tablets 5mg inhibits the action of cholinesterase, which slows down the degradation of acetylcholine released by acetylcholine-producing neurones that are still functional, and this increases levels of acetylcholine in the damaged areas of the brain.  Donepezil Rex tablets 5mg slow down the progression of Alzheimer's Disease and dementia to improve daily functioning, memory and clear thinking, but cannot prevent the loss of cognitive function, stop progression or cure the disease. 

What are the side effects of Donepezil Rex?

The most commonly reported side effects when taking Donepezil Rex tablets 5mg include diarrhoea, nausea, vomiting, fatigue, common cold, insomnia, muscle cramps, rash, dizziness, headache, anorexia.

When should Donepezil Rex not be used?

You should not use Donepezil Rex tablets 5mg if you:

• are allergic to donepezil or any ingredients in Donepezil Rex
• are pregnant or are breastfeeding, without consultation with your doctor
• have a heart condition due to a rhythm disorder like sick sinus syndrome
• have a gastrointestinal condition with increased risk of gastric or intestinal ulcers
• have seizures or convulsions as Donepezil may worsen your condition
• have asthma or other chronic obstructive pulmonary disease
• are taking medicines that interact with Donepezil Rex including the antifungal ketoconazole, the anticonvulsants carbamazepine and phenytoin, the antibiotic rifampicin for tuberculosis, the sedative phenobarbital, alcohol, the corticosteroid dexamethasone, cholinergic agonists, beta blockers

What medications interact with Donepezil Rex?

Several medications interact with Donepezil Rex tablets 5mg and should either not be taken while you are taking Donepezil Rex or only after discussion and instruction from your doctor:

• Drugs that cause a serious reaction with Donepezil Rex: cholinergic agonists, beta blockers
• Drugs that affect Donepezil Rex: the antifungal ketoconazole, the anticonvulsants carbamazepine and phenytoin, the antibiotic rifampicin for tuberculosis, the sedative phenobarbital, alcohol, the corticosteroid dexamethasone

How should Donepezil Rex be taken?

You should take your Donepezil Rex tablets 5mg swallowed whole with a glass of water, once daily in the evening before bedtime and with or without food.  The dose you take depends on how well you respond and may be increased depending on your doctor’s recommendation.  You should continue to take your Donepezil Rex tablets 5mg for as long as recommended by your doctor. 

How long should you take Donepezil Rex?

You should continue to take your Donepezil Rex tablets 5mg or as long as recommended by your doctor. 

Missed dose of Donepezil Rex

If you miss a dose of Donepezil Rex tablets 5mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Donepezil Rex be stored?

You should store your Donepezil Rex tablets 5mg below 25°C in a cool dry place. 

References

1. Gandy S.  The role of cerebral amyloid β accumulation in common forms of Alzheimer disease.  J Clin Invest 2005 May 2; 115(5): 1121–1129.