Phase II studies are the first exposures of a drug in patients and are therefore
pivotal in drug development as they give the first information on clinical efficacy.
Before the regulatory bodies can allow a Phase II study to be performed, additional
animal data are required. Late Phase II studies may be lengthy and must be supported
by animal exposures that exceed or are equal to the duration of the clinical
exposure. Additional genetic toxicology studies are required to look at damage
to DNA and, often for the first time, female volunteers of childbearing potential
may be enrolled onto the study. To support their involvement, reproductive safety
studies may be required to ascertain risk to the potential mother and the developing
foetus. The extent of these studies is dependent upon the regulatory body chosen
and the use or otherwise of adequate contraception.
Absorption, distribution, metabolism and excretion (ADME)
studies should also be performed. Huntingdon Life Sciences would advise
that these studies are conducted relatively early on in development
as the data may present an opportunity to further optimise the formulation
before the conduct of larger clinical studies.
Again exposures must be quantified through pharmacokinetic
analysis with a bioanalytical method validated to the requirements of
Good Laboratory Practice (GLP).
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