E-drug: 11th Model List of Essential Drugs (cont'd)
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The question whether Anti-retroviral drugs in their present form should
be on the WHO Model list of essential drugs is an issue which
depends on an understanding of the term "essential".
Firstly this is a model list and any country can decide to add any drug
not on the WHO Model list to their countries Essential drug list. It is
not a prescriptive list, it is a list which should be a starting point for
considering what drugs should be on the national EDL. Also, we
should remember that we are basically talking about a public sector
drug list. This is not a list for registration. In that case, the criteria
for
inclusion is based only on safety, quality and efficacy.
For an essential drug list additional criteria are needed, and these I
would suggest would include ease of use without difficult monitoring
systems, relative efficacy in terms of whether these drugs cure or
alleviate a condition and some assessment of relative cost.
If we look at anti-retrovirals, I think that for many countries the
condition of their health systems is such that they would not be able
to use these drugs effectively. For example if a country is unable to
screen and treat syphilis in pregnancy, then I do not think that country
could manage a zidovudine vertical transmission program effectively.
In these countries, zidovudine would not be considered as an essential
drug. Neverapine has been included on the list on the basis of one
study in Uganda in which nearly 80% of eligable participants were
excluded. I think that the inclusion of neverapine was premature. We
need more evidence. If larger trials show that it is possible to provide
routine treatment to pregnant mothers and their children without
screening or side effects, and that this treatment is effective in
preventing transmission then this drug could be considered to be an
essential drug. But I do not think we have enough evidence yet.
When we come to anti-retrovirals, we have even less evidence that in
the public sector environments that are the venue for the use of these
drugs, that they can be used effectively. We have a very good
comparison disease, Tuberculosis. This is a disease which can be
diagnosed with a simple microscopic slide test of a sputum specimen.
It requires daily treatment with four drugs for two months and two
drugs for six months. In some environments these drugs are combined
into single tablets or combo packs. Minimal monitoring is required,
only observation that the individual takes the drugs and a repeat
smear at 2 and 6 months. Yet for such an easy disease to cure, many
countries cure less than 50% of their patients. If we think of trying to
provide multiple different anti-retrovirals, taken at different times
during the day, for years without achieving a cure, then I think the
practical challenges become clear. Also as I understand it, present
practice is to require regular monitoring with CD4 counts and viral
load measurements. These are difficult, sophisticated tests that may
well be beyond the means of these public health systems to provide.
So again, I do not think we have enough evidence that these drugs
can be used effectively. We need operational field trials in these
environments to assess whether these drugs can be used effectively
in terms of delivery, compliance and positive effect.
Some countries like Brazil and Thailand which are at a more advanced
stage of health system development may be able to use these drugs
effectively and so those countries may choose to add these ARV's to
the list.
There are already drugs on the essential drug list which can be used
for prophylaxis which are not being used. Surely these should be the
first priority.
Nothing in what I have said above should detract from efforts to
reduce prices. Some countries will have the capability to use these
drugs and every effort should be made to ensure their availability.
But I think the WHO Expert committee would have made a mistake to
declare anti-retrovirals "essential" on the Model list. These drugs are
difficult to use, do not achieve a cure, require sophisticated monitoring
and would take resources away from the treatment of diseases such
as TB, ARI, STD's and other such conditions that should be addressed
first. When better drugs are available or if evidence is provided that
the existing drugs can be used empirically without monitoring and
with good outcomes, then I would consider them to qualify to be
termed "essential".
So I would support large scale operational field trials of ARV's to see
whether they can be used in this way.
Richard Laing
Associate Professor of International Health
Boston University School of Public Health
715 Albany St, T4W, Boston MA 02118 USA
Tel 617 414-1444 Fax 617 638-4476
E-mail richardl@bu.edu
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