Abstract: A unit dose medicament storing and mixing system is described having a dual compartmented and collapsible container for use in an intravenous administration system. One of the compartments contains unit dose measurements of sterile medicament (in powder or liquid form), the second compartment to contain sterile intravenous fluid to be used as a diluent. The two compartments are separated by a closure which is separable and resealable. An external clamping device is used to lock the resealable closure and keep the compartments separate. Prior to the infusion of the activated medicament to the patient, the drug is prepared by removing the external clamp and separating the resealable membrane device, thereby providing fluid communication between chambers and effecting intermixing of the contents thereof. The membrane can then optionally be resealed in order to separate the medicament to be delivered from any residual air left in the container.