Evidence lacking on adherence to combination drugs
Reliable evidence about the impact of combination drugs on patient adherence is lacking, say researchers, providing companies with little incentive to invest in such products.
The researchers searched electronic databases and identified 15 studies
in which the use of a combination pill or a unit-of-use packaging system
was compared with more traditional presentations. A combination pill
is defined as two or more drugs in fixed proportions in the same formulation
and unit-of-use packaging system is, for example, medicines to be taken
together being blister- packaged together.
The studies all included at least one outcome measure relating to adherence,
the pharmacological goal of medication or the cost of therapy.
Although the researchers found a statistically significant trends towards
improved adherence in seven out of 13 trials (53 per cent), they say
that differences in the methodology used by different researchers cloud
interpretation and that almost all of the studies were too small or had
inadequate follow-up time.
They point out that fixed-dose combination pills and unit doses can reduce
medicines wastage, lower shipping costs, prevent short supply of individual
components and avoid under-treatment of diseases in both developing and
developed countries. However, they describe the lack of reliable evidence
about these strategies as “extraordinary” given the investment
in assessing the efficacy of separate medicines and the number of people
taking multiple medicines (Bulletin of the World Health Organization 2004;82:935). |
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