Bifurcation model of drug dependence

Chronic administration of narcotics produces alterations which persist for a long time following cessation of drug usage in a state of abstinence. The current model of drug dependence which is based on the narcotic-induced alterations of adenylatecyclase synthesis and activity cannot explain these long-term changes. The possible modification of this model suitable to explain the state of abstinence, is described. The modified model consists of two non-linear differential equations describing the dynamics of enzyme synthesis and enzyme-product interaction. Under certain conditions narcotics interconvert the regulatory system from ‘normalʹ equilibrium to an ‘abstinentʹ state in which the system can remain indefinitely, even in the absence of narcotics.