Table 3.

Pharmacokinetic/pharmacodynamic (PK/PD) indices and the magnitudes associated with antiviral clinical efficacy and toxicity

Antivirals	PK/PD index	Pre-clinical PK/PD target for efficacya	Clinical PK/PD target for efficacy	Clinical PK/PD threshold for toxicity
Aciclovir/valaciclovir	Unclear	Unclear	Unclear	Unclear
Foscarnet	Unclear	Unclear	Unclear	No data
Ganciclovir/valganciclovir	AUC	Unclear	AUC: 40–60 mg h/L (Prop)	Unclear
Oseltamivir/oseltamivir carboxylate	Unclear	Unclear	Unclear	Unclear
Ribavirin	AUC	Unclear	AUC0–4 > 1755 mg h/L AUC0–12 > 3014 mg h/L Cmin ≥ 2 mg/L	Cmin > 2.3 mg/Lb

AUC = area under the concentration–time curve; AUC_0–4 = the ratio of the area under the concentration–time curve during a 4-h period; AUC_0–12 = the ratio of the area under the concentration–time curve during a 12-h period; C_min = trough drug concentration; PK/PD = pharmacokinetic/pharmacodynamic; Prop = prophylaxis

^aWhilst in vitro concentrations at which viral replication is inhibited by 50% (i.e. EC₅₀ representing antiviral activity) have been widely determined, there are no/limited data which correlate these values with in vivo pharmacokinetic parameters (e.g. AUC) to describe magnitudes required for pre-clinical efficacy

^bMostly related to anaemia