Calculate the AUC percent extrapolated
pk.calc.aucpext(auclast, aucinf)The numeric value of the AUC percent extrapolated or NA_real_ if
any of the following are true is.na(aucinf), is.na(auclast),
aucinf <= 0, or auclast <= 0.
the area under the curve from time 0 to the last measurement above the limit of quantification
the area under the curve from time 0 to infinity
aucpext is 100*(1-auclast/aucinf).