Zopiclone-associated methemoglobinemia and renal impairment

Figures & data

Table 1.  Detailed blood and urine investigation results of the patient

Investigations		Day 0 (admission)	Day 1	Day 2	Day 3	Day 4 (discharge)	Day 6 (follow up)	Normal values
Complete blood count	White blood cell	11.5^a	9.5	10.0	9.2	9.9	–	3.9–10.7 × 10^9/L
	Hemoglobin	12.4	10.2	10.5	10.8	11.1	–	11.6–15.5 g/dL
	Platelet	293	268	324	355	414	–	152–358 × 10^9/L
Renal function test	Blood urea nitrogen (BUN)	36	43	30	30	26	23	8–22 mg/dL
	Creatinine	4.2^b	5.3	5.1	3.3	2.0	1.3	0.6–0.9 mg/dL
	Sodium	138	134	142	142	138	141	136–148 mmol/L
	Potassium	4.2	4.5	4.0	3.6	3.9	3.4	3.6–5.0 mmol/L
	BUN/creatinine	8.6	8.4	5.9	9.1	13.0	17.7	>20 in pre-renal failure
Liver function test	Bilirubin	12	13	–	18	19	–	4–23 μmol/L
Other blood test	Haptoglobin	–	1.29	–	–	–	–	0.16–1.97 g/L
Urine tests	Microscopy	Inconclusive^c	–	–	–	–	–
	Sodium	–	46	–	–	–	–	<20 mmol/L in pre-renal failure
	Creatinine	–	30.8	–	–	–	–	0.6–0.9 mg/dL
	Fractional sodium excretion	–	5.9%	–	–	–	–	<1% in pre-renal failure
Toxicology tests	Blood methemoglobin	19.4	6	4.4	1.6	1.6	–	<1.5%
	Serum zopiclone concentration	1,690	215	–	32	<10	–	40–70 ng/mL in peak therapeutic level, >600 ng/mL in lethal dose
	β2-Microglobulin	–	6.2	–	–	–	–	<0.2 μg/mL

^aNeutrophil 8.54, lymphocyte 2.09, monocyte 0.55, eosinophil 0.14, and basophil 0.04.

^bThe patient had normal renal function (blood creatinine of 0.6 mg/dL) 2 months before the overdose.

^cProtein 100 mg/dL; red cells <30/μL; white cells 10–50/μL; and no cast, epithelial cells, and bacteria present. Urine culture had insignificant bacterial growth.