1. Clinical Overview
Rivastigmine is a reversible, non-competitive, brain-selective, dual inhibitor of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), used for the symptomatic treatment of mild to moderate dementia of the Alzheimer's type and dementia associated with Parkinson's disease. The 1.5mg strength is typically the initial dose for titration.
| Onset | Duration | Bioavailability |
|---|---|---|
| Pharmacodynamic effects begin within 1-2 hours of oral administration, but clinical improvement in cognition and global function may take several weeks of continuous therapy. | Approximately 10-12 hours, supporting a twice-daily (BID) dosing regimen. | Approximately 36% for the oral capsule. Bioavailability increases by 30-50% when taken with food. |
2. Mechanism of Action
Rivastigmine exerts its therapeutic effect by enhancing cholinergic function in the cerebral cortex and hippocampus, brain regions critically involved in memory, attention, and learning, which are deficient in Alzheimer's and Parkinson's disease dementia. It does this by inhibiting the enzymes that break down acetylcholine.
3. Indications & Uses
- Mild to moderate dementia of the Alzheimer's type
- Mild to moderate dementia associated with Parkinson's disease
4. Dosage & Administration
Adult Dosage: Initial dose: 1.5 mg twice daily. Titration: Increase by 1.5 mg twice daily increments at minimum intervals of 2 weeks, based on tolerability. Effective dose range: 3 mg to 6 mg twice daily (6-12 mg/day). Maximum recommended oral dose: 6 mg twice daily (12 mg/day).
Administration: Administer twice daily, in the morning and evening, with food to improve tolerability and increase bioavailability. Capsules should be swallowed whole with a glass of water. Do not crush or chew.
5. Side Effects
Common side effects may include:
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Dyspepsia
- Anorexia (loss of appetite)
- Weight loss
- Dizziness
- Headache
- Fatigue
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Metoclopramide | Additive extrapyramidal effects; increased risk of parkinsonian symptoms. | Major |
| Beta-blockers (e.g., Propranolol, Atenolol) | Additive bradycardic effect; risk of syncope, heart block. | Major |
| Other Cholinesterase Inhibitors (Donepezil, Galantamine) | Additive cholinergic effects and toxicity; contraindicated. | Major |
| Anticholinergic drugs (e.g., Atropine, Oxybutynin, Tricyclic Antidepressants) | Pharmacological antagonism; may reduce rivastigmine efficacy. | Moderate |
| Cholinergic agonists (e.g., Bethanechol) | Additive cholinergic effects; risk of toxicity. | Moderate |
| Succinylcholine-type muscle relaxants | Prolonged neuromuscular blockade during anesthesia. | Moderate |
| NSAIDs (e.g., Ibuprofen, Diclofenac) | Increased risk of gastrointestinal bleeding. | Moderate |
7. Patient Counselling
- DO take with food (breakfast and dinner).
- DO swallow the capsule whole with water.
- DO follow the prescribed titration schedule; do not increase dose faster than instructed.
- DO inform all doctors and surgeons you are taking rivastigmine before any procedure.
- DO NOT stop the medication abruptly without consulting your doctor.
- DO NOT crush or chew the capsule.
- DO NOT take a double dose if you miss one. Skip it and take the next at the regular time.
8. Toxicology & Storage
Overdose: Severe nausea, vomiting, salivation, sweating, bradycardia, hypotension, respiratory depression, convulsions, muscle weakness (including respiratory muscles), and cholinergic crisis (SLUDGE syndrome: Salivation, Lacrimation, Urination, Defecation, Gastrointestinal upset, Emesis).
Storage: Store below 30°C. Protect from moisture. Keep in the original blister pack or container. Keep out of reach and sight of children.