Defined daily dose

The defined daily dose (DDD) is a statistical measure of drug consumption, defined by the World Health Organization (WHO). It is used to standardize the comparison of drug usage between different drugs or between different health care environments. The DDD is not to be confused with the therapeutic dose or with the dose actually prescribed by a physician for an individual patient. The defined daily dose (DDD) is a statistical measure of drug consumption, defined by the World Health Organization (WHO). It is used to standardize the comparison of drug usage between different drugs or between different health care environments. The DDD is not to be confused with the therapeutic dose or with the dose actually prescribed by a physician for an individual patient. The WHO's definition is: 'The DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults.' A common problem when comparing drugs is that different medications can be of different potency. For example, 20 mg of the beta blocker propranolol are much less effective than 20 mg of the beta blocker bisoprolol. To reflect this, the WHO has decided on a DDD for propranolol of 160 mg and for bisoprolol of 10 mg. Individual patients can still be prescribed higher or lower doses, for instance in children, patients with liver or kidney impairment, patients with a combination therapy, or due to differences in drug metabolism between individuals or ethnicities (genetic polymorphism).