Comparison on Pharmacokinetic Parameters of Innovative Valganciclovir Versus Generic Valganciclovir in Kidney Transplant Recipients

Cytomegalovirus (CMV) is the most common opportunistic viral pathogen in solid organ transplant receptors (SOTR). In the absence of prophylaxis, the frequency of CMV disease in high-risk recipients (R- / D +) is 60% and 20% for intermediate-risk patients (R + / D + or -). For universal prophylaxis, the antivirals most commonly used are valganciclovir (valGCV) and IV ganciclovir. ValGCV, a prodrug of ganciclovir, has a bioavailability of 60%, which represents more than 10 times that those obtained with ganciclovir.

Pharmacokinetic studies of Valganciclovir in SOTR have been demonstrated that insufficient doses can diminish its clinical efficacy and the development of viral resistance, while excessive doses can increase its toxicity.

The risk of viremia may be associated with ineffective plasma doses, as described by Wiltshire et al., where values of the area under the curve (AUC) between 40 and 50 μg/h/ml were associated with a lower incidence of viremia, while lower AUC values are associated with an increase 8 times more for viral replication rates. As a result, pharmacokinetic studies in SOTR guide the investigators in continuing with the research of their clinical impact.

A generic drug before their release to the market needs to show that is bioequivalent with the innovative drug, assuming that it has the same therapeutic effects.

The studies for demonstrate bioequivalence are carried out in controlled conditions with healthy participants, different of SOTR characteristics as: age, gender, race, comorbidities and concomitant medication. In addition, the excipients used in generic drug are different from those of the innovative drug, so the properties of the formulation can be modified (particle size or half-life), therefore, the efficacy and drug safety.