Fever, Constipation, and a Stopped Cigarette

This is a medical emergency, not a medication review. Fever plus sore throat plus ANC 1.2 is febrile neutropenia until proven otherwise; five days without stool plus distension plus vomiting is evolving ileus, a recognised and potentially fatal clozapine complication.

Actions:

1. Stop clozapine now. Do not give the next dose.
2. Same-day transfer to a medical inpatient bed with psychiatric liaison, not home.
3. Repeat FBC with differential immediately and daily; add CRP, LFTs, renal function, electrolytes, lipase if abdominal pain, blood cultures, and an abdominal X-ray or CT to look for ileus or impaction.
4. IV fluids; nil by mouth if obstruction is suspected; surgical review; do not push laxatives blindly into a possible obstruction; antiemetic and antipyretic as medically advised; broad-spectrum antibiotics for febrile neutropenia per the treating team.
5. ECG (QTc) and, if it can be sent externally, a clozapine level.

Thresholds to state explicitly. ANC 1.5 or above: continue. ANC 1.0-1.5: interrupt clozapine, monitor FBC at least daily, and rechallenge only after medical review and recovery above 1.5. ANC below 1.0: clozapine should not be restarted in most protocols. His ANC is 1.2 - in the interrupt-and-monitor band, but the clinical picture (fever, possible ileus, likely raised level) makes this more than a laboratory problem.

Record the reasoning in the notes, inform the cousin with the patient's consent or on the basis of necessity, and arrange psychiatric follow-up for the post-discharge antipsychotic plan.

Two hits on CYP1A2, converging.

Smoking cessation. Tobacco smoke contains polycyclic aromatic hydrocarbons that induce CYP1A2, the main enzyme clearing clozapine. When he stopped four weeks ago, that induction decayed over roughly two to four weeks, so his clozapine level rose substantially on an unchanged dose - commonly in the range of 30-80%. The signature is exactly what he shows: sedation, drooling, slowness, and a lowered seizure threshold.

Ciprofloxacin. A potent CYP1A2 inhibitor, started ten days ago. Added to the loss of smoking induction, the effective clearance falls further and the level can roughly double.

Constipation. Clozapine's strong muscarinic blockade slows gut motility; the elevated level worsens it. Five days without a bowel movement plus distension plus vomiting is the point at which ileus, impaction and perforation enter the differential, which is why bowel function must be asked about at every visit and prophylactic laxatives are standard.

Neutropenia. Clozapine carries a monitored risk of neutropenia and agranulocytosis, usually early but not exclusively so; this is why ANC is checked at defined intervals and why any fever or sore throat triggers an urgent count.

What should have happened: the GP, on prescribing ciprofloxacin, should have flagged the interaction; a smoker who quits on clozapine should have a level checked or a pre-emptive dose review within one to two weeks; the weekly nurse review should have included bowel habit, temperature, sedation and drooling; and the monitoring schedule should have been documented somewhere the GP could see it. Write a letter to the GP after this episode setting out the CYP1A2 interactions he must avoid - fluvoxamine, ciprofloxacin and other quinolones, heavy caffeine - and the need to re-titrate after any smoking change.

Assess capacity, do not assume it. Capacity is decision-specific: can he understand the relevant information (that he has a low white-cell count with fever, a possibly obstructed bowel, and a raised drug level), appreciate that it applies to him, reason with it, and communicate a choice? His slowness and probable clozapine toxicity make delirium a real possibility; if attention and orientation fluctuate, capacity is impaired by definition and the decision defaults to protective care. Record the actual questions you asked and his answers, not just the conclusion.

If he retains capacity, capacity does not by itself end the matter: a treatable life-threatening condition, an untreated psychotic illness, and a refusal that would predictably lead to harm allows protective measures under the mental health legislation and MOH admission procedures, with a documented second opinion where the process requires it. Confirm the current procedure with the hospital's medico-legal office rather than relying on memory.

Least restrictive plan: voluntary medical admission if he agrees; if not, involuntary medical admission with psychiatric liaison, one-to-one observation, and the reason stated in the notes. Contact the cousin as next of kin, with consent or on grounds of necessity. Involve the social worker for the home situation. After medical stabilisation, review the antipsychotic: clozapine may be contraindicated if ANC falls below 1.0, so plan an alternative, arrange metabolic and bowel monitoring, and ensure the community nurse has a written monitoring sheet.