An Application of Gradual Reduction of Drug Dose to HIV Infection Model in Consideration of Drug Resistance and Drug Dose

It is known that the HIV (Human Immunodeficiency Virus) infection that causes AIDS is a dynamic process that can be modelled mathematically. By changing the drug effect in the model, which can be regarded as the control input, the primary goal of this paper is to drive any initial state into an equilibrium called the `non-progressor,' where the infected patient will not develop symptoms of AIDS. In this paper a new method of treatment is proposed and realised by a routine. This method is based on the gradual reduction of drug dose (GRDD), which can be roughly stated as `slow reduction of dose after the maximum dose for a period'. The new treatment idea improves GRDD in the sense of reducing the emergence of drug resistance and decreasing the amount of drug used. These improvements are demonstrated by computer simulations, and it is concluded that the improved treatment can limit the chance of emergence of the resistant strains to the extent of full HAART suppression, even though the process of the treatment includes partially suppressive HAART.