case_images: PMC11143807_01
case_images: Clozapine and norclozapine levels in time.. Arrow 0: 'baseline' plasma levels on clozapine 600 mg once daily + valproic acid; arrow 1: addition of fluvoxamine 25 mg, clozapine dose adjusted to 500 mg once daily; arrow 2: valproic acid replaced by carbamazepine; arrow 3: clozapine dose increased to 550 mg once daily, fluvoxamine dose increased to 50 mg; arrow 4: admission to hospital, diagnosed with paralytic ileus; after discharge clozapine dose decreased to 450 mg once daily and carbamazepine dose increased; arrow 5: readmission to hospital with suspected paralytic ileus.
case_images: 10.1177_20451253241255487-fig1.jpg
case_images: PMC11143807_01_10.1177_20451253241255487-fig1.jpg
case_images: fig1-20451253241255487
case_images: Clozapine dose was adjusted from 600 to 500 mg once daily at the same time (Figure 1, arrow 1). Two weeks after starting fluvoxamine, carbamazepine (200 mg twice daily) was added and valproic acid was stopped (Figure 1, arrow 2). Therefore, both fluvoxamine and clozapine doses were increased (to 50 mg and 550 mg once daily, respectively) (Figure 1, arrow 3). Drug concentration levels showed increasing norclozapine in the weeks before hospital admission, and an inverted clozapine/norclozapine ratio 2 days before admission was observed (Figure 1, arrow 4). Again, there was an inverted ratio, with clozapine level being 270 microg/l and norclozapine level 280 microg/l (Figure 1, arrow 5).
case_images: Clozapine metabolism.. In bold, the main enzymes involved.. CYP, cytochrome P450; FMO3, flavin-containing monooxygenase3 enzyme; N-desmethylclozapine, norclozapine; SULT's, sulfotransferases; UGT's, UDP-glucuronosyltransferases.
case_images: 10.1177_20451253241255487-fig2.jpg
case_images: PMC11143807_01_10.1177_20451253241255487-fig2.jpg
case_images: fig2-20451253241255487
case_images: Two weeks after starting fluvoxamine, carbamazepine (200 mg twice daily) was added and valproic acid was stopped (Figure 1, arrow 2).