2. Pharmacokinetic Studies
Most of the recognised important differences between younger and older patients have been pharmacokinetic differences. This is often related to impaired excretion (due to kidney or liver problems) or interactions between medicines.
The information regarding age-related differences in the pharmacokinetics of the medicine can come either from a pharmacokinetic screen or from formal pharmacokinetic studies in the elderly and in patients who have problems with eliminating waste products from the body. It is important to find out whether or not the pharmacokinetic behaviour of the compound in elderly patients is different from that in younger adults. The effects of influences which are more common in the elderly, such as abnormal kidney or liver function should be characterised.
Pharmacokinetic studies in patients with kidney problems:
Kidney impairment is associated with aging but can also occur in younger patients. Therefore, it is a general principle, that medicines excreted mainly through the kidneys should be studied to define the effects of altered kidney function on their pharmacokinetics. To get this information, studies should include elderly participants. Alternatively, the information can be obtained in younger participants with kidney impairment.
Pharmacokinetic studies in patients with liver problems:
Medicines that are broken down and/or excreted in the liver, or that have active metabolites, may pose special problems of liver impairment in the elderly. Pharmacokinetic studies should also be carried out in elderly participants or alternatively, in younger people with liver impairment.