Time-varying pharmacodynamics in a simple non-integer HIV infection model.

•the effect of time-varying drug exposure in HIV infected patients is studied in a fractional order model.•the slope of the dose-response curve, the drug’s half-life, and the dosing interval impact significantly the dynamics of the proposed model.•the order of the fractional derivative can be used to deepen the understanding of the pharmacodynamics of HIV, necessary for more accurate therapeutic regimens.