Adult dose and durationStarted tiny and climbed slowly. SmPC verbatim: "12.5 mg once or twice on the first day, followed by 25 mg once or twice on the second day. If well tolerated, the daily dose may then be increased slowly in increments of 25 to 50 mg in order to achieve a dose level of up to 300 mg/day within 2 to 3 weeks. Thereafter, if required, the daily dose may be further increased in increments of 50 to 100 mg at half-weekly or, preferably, weekly intervals." Therapeutic range verbatim: "In most patients, antipsychotic efficacy can be expected with 200 to 450 mg/day given in divided doses." Ceiling verbatim: increments "not exceeding 100 mg" are permissible "up to 900 mg/day", with "the possibility of increased adverse reactions (in particular seizures) occurring at doses over 450 mg/day" borne in mind. Nothing is started unless the count allows it: the SmPC restricts initiation to patients whose white cell count is at least 3,500 per cubic millimetre and whose absolute neutrophil count is at least 2,000 per cubic millimetre, both within normal limits. - Six months at least, then reviewed downward. SmPC verbatim: "Treatment should be maintained for at least 6 months." Stopping is gradual - "a gradual reduction in dose over a 1 to 2-week period is recommended."
Paediatric doseNot a paediatric prescription. SmPC verbatim: "The safety and efficacy of Clozaril in children and adolescents under the age of 16 years have not yet been established. It should not be used in this group until further data become available."
Dose sourceClozaril 25 mg Tablets SmPC sections 4.1, 4.2 and 4.4 (eMC product 4411)
WhyThe disease article states the indication twice, verbatim: "For these patients, clozapine is the recommended treatment option, with about 40% of those with treatment-resistant schizophrenia responding." and "Clozapine is also recommended for patients with schizophrenia with persistent, substantial risks of suicide or aggression despite other treatments." The SmPC's indication section names the same patient, verbatim: "Clozaril is indicated in treatment-resistant schizophrenic patients and in schizophrenia patients who have severe, untreatable neurological adverse reactions to other antipsychotic agents, including atypical antipsychotics." It sits at line 3 because resistance is defined by what came before it, the article's own definition being persistent symptoms "despite 2 or more trials of antipsychotic medications at adequate doses and durations, with documented adherence." Fourteen Egyptian products are registered, ZACLO 100 mg at 19.20 EGP through LEPONEX; the blood monitoring, not the price, is what limits its use.
Cautions- RED FLAG - agranulocytosis. Any fever, sore throat or flu-like illness on clozapine is an urgent full blood count the same day, not a wait-and-see. SmPC verbatim: "Clozaril can cause agranulocytosis."
- The blood count schedule is a condition of prescribing, not advice. SmPC verbatim: regular white cell and absolute neutrophil counts "weekly during the first 18 weeks of treatment, and at least every 4 weeks thereafter throughout treatment. Monitoring must continue throughout treatment and for 4 weeks after complete discontinuation".
- Contraindicated in anyone who cannot be monitored. SmPC verbatim: "Patients unable to undergo regular blood tests." and "History of toxic or idiosyncratic granulocytopenia/agranulocytosis".
- Cardiac assessment before the first dose. SmPC verbatim: "Patients with history of cardiac illness or abnormal cardiac findings on physical examination should be referred to a specialist for other examinations that might include an ECG, and the patient treated only if the expected benefits clearly outweigh the risks". Myocarditis in the first weeks is the classic presentation.
- DRESS ends the drug permanently. SmPC verbatim: "If the patient has developed DRESS with the use of clozapine, treatment with clozapine must not be restarted in this patient at any time."
- Two days off and the titration restarts from the beginning. SmPC verbatim: "In patients in whom the interval since the last dose of Clozaril exceeds 2 days, treatment should be re-initiated with 12.5 mg given once or twice on the first day." A missed weekend is a real hazard, not a technicality.
- Seizure risk rises with dose, and constipation on clozapine can progress to bowel obstruction - both are asked about at every review.