Clozapine Flashcards
Clozapine
2nd generation (atypical) antipsychotic
Most effect
Use
Licensed for resistant schizophrenia
Tried 2 or more drugs (including a 2nd gen) for min 6-8 weeks each.
Duration
Try for min 8-10 weeks to assess effectiveness.
No response to optimized dose - measure Cp levels before augmenting with 2nd antipsychotic.
Missed dose
> 2 missed doses = re-initiate by specialist
Interactions - increased risk of agranulocytosis
Agranulocytosis (blood dyscrasias)
- Aminosalicylates
- Immunosuppressants e.g. methotrexate, cytotoxic
Side effects
MAG
1. Myocarditis + cardiomyopathy
2. Agranulocytosis + neutropenia
3. GI obstruction
Myocarditis + cardiomyopathy
Persistent tachycardia (esp. in first 2 months)
Physical exam + full medical history before starting
STOP permanently if occurs.
Agranulocytosis + neutropenia
Leucocyte & differential blood count
Every week for 18 weeks, then every 2 weeks for a year, then monthly onwards.
AVOID drugs that depress leucopoiesis
Pt counselling - report flu like illness
GI obstruction
Intestinal peristalsis impaired = constipation, faecal impaction, paralytic ileus.
CAUTION with constipating medicine (e.g. hyoscine for treatment of hypersalivation with clozapine)
Recognise + treat constipation.
Pt. counselling = report constipation before taking next dose.
MHRA/CHM advice (October 2017)
Reminder of potentially fatal risk of intestinal obstruction, faecal impaction + paralytic ileus.
MHRA/CHM advice (August 2020)
Clozapine and other antipsychotics: monitoring blood concentrations for toxicity
MHRA recommends monitoring blood concentration of clozapine for toxicity in certain clinical situations such as when:
- pt. stops smoking or switches to an e-cigarette
- concomitant medicines may interact to increase blood clozapine levels;
- pt. has pneumonia or other serious infection
- suspected reduced clozapine metabolism
reduced clozapine metabolism is suspected;
