Donepezil Hydrochloride
Donepezil hydrochloride (中文: 鹽酸多奈哌齊), is a reversible inhibitor of acetylcholinesterase. It is used for the treatment of mild to moderate dementia in Alzheimer’s disease.
Drug Names[edit]
| Generic Name 藥名 | HA Code 藥物代碼 | Classification藥物分類 |
|---|---|---|
| Donepezil HCL Tablet 5mg | DONE01 | P1S1S3 |
| Donepezil HCL Tablet 10mg | DONE02 | P1S1S3 |
| Donepezil HCL Orodispersible Tablet 5mg | DONE03 | P1S1S3 |
Pronunciation[edit]
Donepezil hydrochloride 10mg (ARICEPT 10mg)[edit]
Donepezil hydrochloride 5mg (ARICEPT 5mg)[edit]
Mechanism of Action[edit]
Acetylcholinesterase inhibiting drug
Dosage[edit]
| By Oral | nitially 5 mg once daily at bedtime, increased if necessary, after one month to max. 10 mg daily.
Clinical benefit should be assessed on a regular basis. Up to half the patients will show a slower rate of cognitive decline. Donepezil should be discontinued in those not responding. |
|---|
Side Effects[edit]
Common side effects include
- Nausea and vomiting
- difficulty sleeping
- aggression
- Loss of appetite
- Diarrhoea
- Feeling tired
- Muscle cramps
These effects usually last 1 – 3 weeks and then lessen
Serious side effects may include:
- Abnormal heart rhythms
- Difficulty emptying urine from the bladder
- seizures
Donepezil, like other acetylcholinesterase inhibitors, can cause nightmares due to enhanced activation of the visual association cortex during REM sleep. Taking donepezil in the morning can reduce the frequency of nightmares.
Pharmacokinetics[edit]
| Oral bioavailability | Donepezil hydrochloride is readily absorbed from the gastrointestinal tract with a relative oral bioavailability of 100%. It is about 95% bound to plasma proteins, mainly albumin. |
|---|---|
| Onset of action | Peak plasma levels in 3-4 hours |
| Elimination half-life | 70 hours, but around 100 hours in elderly |
| Duration of action | With daily dosing, steady-state concentration is reached within 3 weeks after initiation of therapy. Once at steady-state, plasma donepezil hydrochloride concentrations show little variability over the course of the day. |
How long does it take for donepezil to take effect?[edit]
Donepezil may take as long as 12 weeks to begin working.
What time of day should donepezil be taken?[edit]
It is usually taken once a day with or without food, just before bedtime. Take donepezil at around the same time every day.
Why is donepezil taken at night?[edit]
Donepezil is taken at night because it can cause irregular or slow heartbeat for some patients, which can cause fainting. When it is taken at bedtime, affected patients will be able to sleep through those side effects.
Drug Management[edit]
Monitoring[edit]
- Acetylcholinesterase inhibitor may increase gastric acid secretion, so patients should be monitored closely for GI bleeding, especially those receiving concurrent NSAID drugs.
- Check body weight regularly
- Monitor the cognitive, global functions, and ADL activities
- Monitor the sleeping quality
Drug interaction[edit]
| CYP2D6 inhibitors:
SSRI, such as Paroxetine quinidine |
May increase plasma-donepezil concentration, increasing the risk of severe adverse reactions. |
|---|---|
| May increase plasma-donepezil concentration,
increasing the risk of severe adverse reactions. |
May increase plasma-donepezil concentration, increasing the risk of severe adverse reactions |
| CYP3A4 inducers & CYP2D6 inducers:
Rifampicin, Phenytoin, Carbamazepine |
May reduce plasma-donepezil concentration |
Caution[edit]
- Cardiovascular conduction disorders such as sick-sinus syndrome
- Susceptibility to peptic ulcers
- Asthma, chronic obstructive pulmonary disease
- People who have a predisposition to seizures
- Concomitant antipsychotic treatment – increased risk of neuroleptic malignant syndrome
Contraindications[edit]
It is contraindicated in patients with a known hypersensitivity to donepezil hydrochloride.
Hepatic and Renal impairment[edit]
A similar dose schedule can be followed for patients with renal or mild to moderate hepatic impairment as clearance of donepezil is not significantly affected by these conditions.
Effects on ability to drive and use machinery[edit]
Donepezil can cause fatigue, dizziness and muscles, mainly when initiating or increasing the dose. The treating doctor should routinely evaluate the ability of patients on donepezil to continue driving or operating complex machines.
FAQ[edit]
How should I take the tablet?[edit]
Donepezil tablet and orodispersible tablet should be taken orally at bedtime, or as directed by the doctor. The orodispersible tablet should be placed on the tongue and allowed to disperse before swallowing with or without water. Both formulations can be taken with or without food.
What should I avoid while taking?[edit]
Avoid abruptly discontinue the medication.
What happen if I overdose?[edit]
Contact your primary care doctor. If emergency situation, call 999
What happen if I miss a dose?[edit]
Take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
