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WHO Collaborating Centre for Drug Statistics Methodology
Norwegian Institute of Public Health
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0213 Oslo

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Tel:  +47 21 07 81 60

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See also C03 - Diuretics, C07 - Beta blocking agents, C08 - Calcium channel blockers and C09 - Agents acting on the renin-angiotensin system.

Antihypertensives are mainly classified at 3rd levels according to the mechanism of action. Most headings are self-explanatory:
C02A Antiadrenergic agents, centrally acting
C02B Antiadrenergic agents, ganglion-blocking
C02C Antiadrenergic agents, peripherally acting
C02D Arteriolar smooth muscle, agents acting on
C02K Other antihypertensives
C02L Antihypertensives and diuretics in combination
C02N Combinations of antihypertensives in ATC gr. C02

The oral DDDs are based on the average doses needed to reduce the blood pressure to a normal level in patients with mild-moderate hypertension.

Parenteral DDDs are based on dosages used for the treatment of hypertensive crises and are based on the content of the active ingredient pr. vial (ampoule).


All substances classified in groups C02A-K, in combination with diuretics are classified in this group. At each 5th level, various combinations containing e.g. different diuretics, other antihypertensives or potassium may occur.

Combinations with beta blocking agents, see comments under C07.

Diuretics in combination with calcium channel blockers are classified in C08.

Diuretics in combination with ACE inhibitors, are classified in

Diuretics in combination with angiotensin II reseptor blockers (ARBs) are classified in C09DA.

The need for a systematic approach to classify combinations of different antihypertensives has resulted in a ranking according to the ATC codes. Substances classified in ATC group C02AA take precedence over C02AB and substances in C02A take precedence over C02B etc.

Example: A combined preparation containing bietaserpine, hydralazine and hydrochlorothiazide will be given the code C02LA07 according to the above mentioned ranking.

Combinations with psycholeptics are classified at separate 5th levels using the corresponding 70-series.

It has been considered most appropriate to assign fixed DDDs based on the average use of the different combinations without considering and comparing the strengths of the various components. 1 tablet is the fixed DDD for products given once daily whereas the fixed DDD for products given twice daily and three times daily is respectively 2 tablets and 3 tablets. The assigned DDDs cannot always be compared with the DDDs assigned for plain preparations.

C02LA Rauwolfia alkaloids and diuretics in combination

List of abbreviations

Last updated: 2018-12-13