Psychotropics in renal and hepatic disease — consultant viva

Station structure

Time: 8–10 minutes. Depth: consultant teaching registrar. Expect named trials (CAST, ASCEND), renally cleared antipsychotic traps, Child–Pugh thinking, LOT benzodiazepines, free-fraction concept, lithium EXTRIP, and valproate HAE without inventing product-label milligrams as universal law.[1][2][3][4]

Core questions and model points

1. How do you approach any psychotropic in organ failure? Stage eGFR/CrCl and Child–Pugh; identify primary clearance; prefer favourable PK; start low; TDM when indicated; emergency exits (toxicity, HE, DILI).[1][6][10]

2. Renally cleared antipsychotics? Paliperidone and amisulpride — dose-reduce or avoid per product thresholds; many hepatically metabolised SGAs relatively preferred in advanced CKD.[1]

3. Depression in CKD? High prevalence; CAST: sertraline ≈ placebo for symptoms in non-dialysis CKD with more GI effects; ASCEND: HD comparative depression treatment trial; do not abandon psychosocial care.[2][3]

4. Lithium toxicity? Stop drug; saline if depleted; serial levels; EXTRIP criteria for extracorporeal treatment; charcoal useless for lithium.[4][8]

5. Cirrhosis and benzos? Minimise; new BZD linked to HE risk (Grønbæk); LOT if essential, low dose, short course.[5][6]

6. Valproate confusion with high ammonia? HAE — stop VPA even if LFTs modest; specialist pathway.[7]

7. Why free fraction matters? Hypoalbuminaemia increases unbound highly bound drugs; total levels mislead.[6][10]

8. TDM culture? 12-hour lithium troughs; AGNP consensus supports concentration-guided care when clearance is unstable.[9]

Examiner traps

• “All SSRIs need the same renal cut.”
• “CAST means never treat depression with meds.”
• “Normal ALT means safe full-dose diazepam in cirrhosis.”
• “Lithium is metabolised by the liver.”
• Forgetting NSAID/ACEI/thiazide lithium interactions.[2][5][8]