Chrono Pharmacokinetics

Chronopharmacokinetics refer to dosing – time (i.e, rhythms-dependant) differences in the absorption, metabolism and elimination of medications.
Temporal changes can be involved at each step of the sequence of pharmacokinetic processes
a) temporal changes in drug absorption,
b) in drug metabolism (enzyme activity, hepatic blood flow) and in renal drug excretion.
Thus, the time of administration of a drug is an important source of variation which must be taken into account in kinetic studies. In a chronopharmacokinetic study many factors relating to the condition of the administration.

There are some instances in which chronokinetic study is needed.

i) When possible daily variation in pharmacokinetics may be responsible for time dependent variations in drug effects,
ii) When drugs have a narrow therapeutic range,
iii) When symptoms of a disease are clearly circadian phase – dependent ( eg. Nocturnal asthma, angina pectoris, myocardial ischemia)

iv) When drug plasma concentrations are well correlated to the therapeutic effect in case the latter is circadian phase- dependent