Table 1. Potentially severe medication errors according to the Anatomical Therapeutic Chemical classification (ATC 1 and 2).

ATC 1 code	ATC 2 code	(n)	Potentially severe medication errors
A	A10	5	Drug omission in diabetes mellitus
		2	Drug substitution in diabetes mellitus
		4	Drug dose change in diabetes mellitus
B	B01	2	Drug omission - antithrombotic drug
		1	Drug dosage frequency change – antithrombotic drug
C	C01	1	Drug omission in cardiac therapy
		2	Drug dose change in cardiac therapy
	C03	1	Drug omission – diuretic drug
	C07	1	Drug dosage frequency change – beta blocker
	C09	2	Drug omission – renin-angiotensin system
		1	Drug substitution – renin-angiotensin system
J	J01	7	Drug omission – antibacterial drug for systemic use
Total		29