A gas-tight pharmaceutical container includes a pharmaceutical bottle defining a main enclosure and an upper neck forming a top opening. The upper neck includes an upper rim forming a planar engagement surface. A screw-on closure cap seals the top opening, and includes a circular top member and a circumferential flange. In one embodiment, the closure cap is metal and includes an annular pliable gasket secured to a peripheral portion thereof and a layer of lacquer applied interiorly of the gasket. In another embodiment, the closure cap is plastic and includes a circular inner liner formed by a base layer, a foil layer adjacent to the base layer, and an annular pliable gasket secured to the foil layer. With either embodiment, threaded engagement of the screw-on closure cap with the pharmaceutical bottle under pressure causes the pliable gasket to sealingly engage the upper rim to provide a gas-tight seal.
