The UK's Committee on Safety of Medicines has issued a warning to doctors
about the risk of mitochondrial dysfunction in infants born to HIV infected
mothers treated with zidovudine (AZT) to prevent vertical transmission.
However, the Committee has told doctors that there are insufficient data to
prove a causal relationship, and that it is important that women do not stop
their treatment in an unplanned way due to scare stories about the effects of
anti-retrovirals on unborn children.
The warning comes in advance of the publication of data from a French study
in which it was discovered that 8 out of approximately 200 infants developed
mitochondrial dysfunction following exposure to zidovudine, with or without 3TC
treatment, for the prevention of vertical transmission of HIV infection.
Mitochondria are the mechanisms within cells by which glucose is transformed
into energy. All nucleoside analogue drugs affect the functioning of
mitochondria to some extent, and may damage mitochondrial DNA, leading to
toxicities such as lactic acidosis and muscle wasting, for example.
Mitochondrial dysfunction in infants may present with neurological
manifestations such as seizures and peripheral neuropathy, and other systemic
effects including cardiomyopathy, lactic acidosis, exocrine pancreatic failure
and bone marrow failure. Two of the infants reported in France died, and the
others presented with symptoms such as seizures, severe cardiomyopathy and
spastic diplegia. In three cases symptoms were asymptomatic. None of the infants
were HIV infected.