Alprazolam-XR is an
extended-release formulation of
alprazolam designed to deliver sustained therapeutic concentrations for 24 h after once-daily dosing. Plasma concentrations gradually decline as the time for the next dose approaches, but still remain above therapeutic minimum levels. The anti-panic efficacy of
alprazolam-XR appears to be comparable to the original formulation of
alprazolam. The main advantage of the new
extended-release formulation appears to be its greater tolerability and safety. The speed with which high-potency
benzodiazepines are absorbed, and rise to peak concentrations is correlated with both abuse potential and with the incidence and severity of common adverse events, such as sedation and cognitive and
psychomotor impairment.
Alprazolam-XR does not exhibit the sudden increases in plasma concentration characteristic of the original formulation of
alprazolam. This pharmacokinetic difference appears to translate into a reduced liability of abuse and a reduced incidence of sedation and cognitive and
psychomotor impairment during acute
therapy. This would appear to give
alprazolam-XR a more favourable benefit:risk profile than the original formulation of
alprazolam. In addition, the once-daily dosing (as opposed to three or four times per day) reduces clock-watching, increases compliance and it eliminates the penalty of breakthrough anxiety and panic that many patients experience if they inadvertently miss a dose. It should be noted that long-term
therapy with
alprazolam-XR carries the same risk of dependence and withdrawal during discontinuation as the original formulation of
alprazolam.