Galantamine: Difference between revisions
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[[Category: Drugs]] [[Category: Acetylcholinesterase inhibiting drug]] | [[Category: Drugs]] [[Category: Acetylcholinesterase inhibiting drug]] | ||
'''Galantamine Hydrobromide''' is a reversible inhibitor of acetylcholinesterase. It also has an intrinsic action on nicotinic receptors. It is used for the treatment of mild to moderate dementia in Alzheimer’s disease. | |||
Galantamine Hydrobromide | |||
{| class="wikitable" | {| class="wikitable" | ||
!Generic Name 藥名 | !Generic Name 藥名 | ||
| Line 22: | Line 18: | ||
|P1S1S3 | |P1S1S3 | ||
|} | |} | ||
==Mechanism of Action== | ==Mechanism of Action== | ||
Acetylcholinesterase inhibiting drug | Acetylcholinesterase inhibiting drug | ||
==Dosage== | ==Dosage== | ||
| Line 36: | Line 30: | ||
Reductions in dose may be necessary in patients with hepatic or renal impairment. | Reductions in dose may be necessary in patients with hepatic or renal impairment. | ||
==Side Effects== | |||
=Side Effects== | |||
Common side effects include | Common side effects include | ||
*Nausea and vomiting | *Nausea and vomiting | ||
| Line 53: | Line 45: | ||
*Difficulty emptying urine from the bladder | *Difficulty emptying urine from the bladder | ||
*seizures | *seizures | ||
==Pharmacokinetics== | ==Pharmacokinetics== | ||
{| class = "wikitable" | {| class = "wikitable" | ||
!style="text-align: left"| Oral bioavailability | !style="text-align: left"| Oral bioavailability | ||
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==Drug Management== | ==Drug Management== | ||
===Monitoring=== | |||
*acetylcholinesterase inhibitor may increase gastric acid secretion, so patients should be monitored closely for GI bleeding, especially those receiving concurrent NSAID drugs. | *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 | *check body weight regularly | ||
| Line 78: | Line 68: | ||
*monitor the sleeping quality | *monitor the sleeping quality | ||
===Drug interaction=== | |||
Hepatic metabolism of donepezil via the cytochrome P450 will be affected by drugs that inhibit the isoenzyme CYP3A4 and CYP2D6 | Hepatic metabolism of donepezil via the cytochrome P450 will be affected by drugs that inhibit the isoenzyme CYP3A4 and CYP2D6 | ||
Interactions do not generally apply to steroid used for topical action including inhalation, unless specified. | Interactions do not generally apply to steroid used for topical action including inhalation, unless specified. | ||
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|- | |- | ||
!style="text-align: left"| CYP3A4 inhibitors: | !style="text-align: left"| CYP3A4 inhibitors: | ||
Erythromycin, | Erythromycin, Itraconazole, Ketoconazole | ||
Itraconazole, | |||
Ketoconazole | |||
|May increase plasma-donepezil concentration, increasing the risk of severe adverse reactions | |May increase plasma-donepezil concentration, increasing the risk of severe adverse reactions | ||
|- | |- | ||
!style="text-align: left"| CYP3A4 inducers & CYP2D6 inducers: | !style="text-align: left"| CYP3A4 inducers & CYP2D6 inducers: | ||
Rifampicin, | Rifampicin, Phenytoin, Carbamazepine | ||
Phenytoin, | |||
Carbamazepine | |||
|May reduce plasma-donepezil concentration | |May reduce plasma-donepezil concentration | ||
|} | |} | ||
===Caution=== | |||
*Cardiovascular conduction disorders such as sick-sinus syndrome | *Cardiovascular conduction disorders such as sick-sinus syndrome | ||
*Susceptibility to peptic ulcers | *Susceptibility to peptic ulcers | ||
| Line 114: | Line 98: | ||
*Concomitant antipsychotic treatment – increased risk of neuroleptic malignant syndrome | *Concomitant antipsychotic treatment – increased risk of neuroleptic malignant syndrome | ||
===Contraindications=== | |||
patients with severe impairment (creatinine clearance less than 9ml/minute. | patients with severe impairment (creatinine clearance less than 9ml/minute. | ||
Patients with known hypersensitivity to galantamine hydrobromide | Patients with known hypersensitivity to galantamine hydrobromide | ||
===Hepatic impairment=== | |||
*no dose adjustment of galantamine is necessary in mild hepatic impairment. | *no dose adjustment of galantamine is necessary in mild hepatic impairment. | ||
*For immediate-release tablet, in moderate impairment, initially 4mg once daily, preferably in the morning, for at least one week, then 4 mg twice daily for at least 4 weeks. Maximum 8 mg twice daily. Avoid in severe impairment | *For immediate-release tablet, in moderate impairment, initially 4mg once daily, preferably in the morning, for at least one week, then 4 mg twice daily for at least 4 weeks. Maximum 8 mg twice daily. Avoid in severe impairment | ||
*For modified-release capsules in moderate impairment, initially 8 mg on alternate days, preferably in the morning for 1 week, then 8 mg once daily for 4 weeks. Maximum 16 mg daily. Avoid in severe impairment | *For modified-release capsules in moderate impairment, initially 8 mg on alternate days, preferably in the morning for 1 week, then 8 mg once daily for 4 weeks. Maximum 16 mg daily. Avoid in severe impairment | ||
===Renal impairment=== | |||
*No dose adjustment is necessary for galantamine in mild or moderate renal impairment. | *No dose adjustment is necessary for galantamine in mild or moderate renal impairment. | ||
*Avoid if eGFR less than 9ml/minute/1.73m2 | *Avoid if eGFR less than 9ml/minute/1.73m2 | ||
===Effects on ability to drive and use machinery=== | |||
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. | 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. | ||
Revision as of 05:35, 30 September 2020
Galantamine Hydrobromide is a reversible inhibitor of acetylcholinesterase. It also has an intrinsic action on nicotinic receptors. It is used for the treatment of mild to moderate dementia in Alzheimer’s disease.
| Generic Name 藥名 | HA Code 藥物代碼 | Classification藥物分類 |
|---|---|---|
| Galantamine HBR Prolonged Release Cap 8mg | GALA04 | P1S1S3 |
| Galantamine HBR Prolonged Release Cap 16mg | GALA05 | P1S1S3 |
| Galantamine HBR Prolonged Release Cap 24mg | GALA06 | P1S1S3 |
Mechanism of Action
Acetylcholinesterase inhibiting drug
Dosage
By Oral: initially 4 mg twice daily for 4 weeks increased to 8 mg twice daily for 4 weeks; maintenance 8-12 mg twice daily according to response and tolerance.
A modified-release preparation is also available for once-daily use. Clinical benefit should be assessed on a regular basis.
Reductions in dose may be necessary in patients with hepatic or renal impairment.
Side Effects
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
Pharmacokinetics
| Oral bioavailability | Donepezil hydrochloride is rapidly and well absorbed from the gastrointestinal tract with an oral bioavailability of about 90%. Plasma protein binding is about 18%. |
|---|---|
| Onset of action | Peak plasma levels in about one hour after ingestion from immediate-release preparations; 4 to 5 hours after a dose of modified-release formulations |
| Metabolism | Partially metabolized by CYP2D6, CYP3A4 |
| Elimination half-life | 7 to 8 hours |
Drug Management
Monitoring
- 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
Hepatic metabolism of donepezil via the cytochrome P450 will be affected by drugs that inhibit the isoenzyme CYP3A4 and CYP2D6 Interactions do not generally apply to steroid used for topical action including inhalation, unless specified.
| Drugs given with donepezil | Potential Effect |
|---|---|
| CYP2D6 inhibitors:
SSRI, such as Paroxetine, Quinidine, Amitriptyline |
May increase plasma-donepezil concentration, increasing the risk of severe adverse reactions. |
| CYP3A4 inhibitors:
Erythromycin, Itraconazole, Ketoconazole |
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
- 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
patients with severe impairment (creatinine clearance less than 9ml/minute. Patients with known hypersensitivity to galantamine hydrobromide
Hepatic impairment
- no dose adjustment of galantamine is necessary in mild hepatic impairment.
- For immediate-release tablet, in moderate impairment, initially 4mg once daily, preferably in the morning, for at least one week, then 4 mg twice daily for at least 4 weeks. Maximum 8 mg twice daily. Avoid in severe impairment
- For modified-release capsules in moderate impairment, initially 8 mg on alternate days, preferably in the morning for 1 week, then 8 mg once daily for 4 weeks. Maximum 16 mg daily. Avoid in severe impairment
Renal impairment
- No dose adjustment is necessary for galantamine in mild or moderate renal impairment.
- Avoid if eGFR less than 9ml/minute/1.73m2
Effects on ability to drive and use machinery
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
How should Galantamine be taken?
Galantamine comes in three forms: as 8mg and 12mg tablets; as Galatamine XL in 8mg, 16mg and 24mg prolonged release capsules; and as an oral solution 4mg/ml. Tablets and oral solution should be administered twice a day, preferably with morning and evening meals. Drink plenty of liquids to keep yourself hydrated.
What should I avoid while taking?
Avoid abruptly discontinue the medication.
What happen if I overdose?
Contact your primary care doctor. If emergency situation, call 999
What happen if I miss a dose?
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.
