Child-resistant closures for containers are well-known and understood to be effective in preventing inadvertent access to potentially dangerous materials, such as prescription medications in such containers, by children. However, such child resistant closures poses problems for elderly people and others with reduced manual dexterity in that it becomes difficult for them to manipulate the closure in order to open the container.
Therefore, although it would be socially desirable to have all medication containers include a child-resistant closure, it is not consider possible to implement this in view of the need to dispense medication to elderly people and others with reduced manual dexterity who might be unable to open a container with a child-resistant closure.
Therefore, convertible container closures have been developed which can be used in both a child-resistant mode and a non-child-resistant mode. For example, U.S. Pat. No. 5,579,934 (Buono) describes a convertible child resistant closure for use with a container having a threaded portion adjacent the container opening, e.g. the container neck, to allow a user to select between a child-resistant configuration and a non-child-resistant configuration. The closure includes coaxial inner and outer caps. The inner cap is defined by a cover wall and a side wall or skirt depending from the cover wall. The side wall includes an inner surface having a threaded portion for engagement with the threaded neck portion of the container and an outer surface including a child resistant portion comprising a series of angular abutments extending thereabout and a non-child resistant portion axially offset from the child resistant portion and preferably in the form of a row of longitudinally extending knurlings. The outer cap is also defined by a cover wall and a side wall depending from the cover wall. The side wall includes an inner surface divided into a first child resistant portion and a second non-child resistant portion axially offset from the first portion. The first portion includes a plurality of angular abutment surfaces complementary to the series of angular abutments on the inner cap and the second portion includes a row of longitudinal knurlings complementary to the knurlings on the inner cap. The inner cap member is positioned within the second cap member and is axially movable between a first position in which the angular surfaces of the inner cap engage the angular abutment surfaces on the outer cap to provide a child resistant closure and a second position in which the knurlings on the outer surface of the inner cap engage the knurlings on the inner surface of the outer cap to provide a non-child resistant closure.
Also, U.S. Pat. No. 5,114,029 (Gibilisco) describes a child resistant bottle closure including an inner cap member, an interlocking member and an outer cap member. The inner cap member includes threads which are secured to a bottle and includes external grooves on its outer circumferential surface. The interlocking member has pins projecting inwardly from its inner circumferential surface and pins projecting outwardly from its outer circumferential surface. The inwardly projecting pins engage and mate with the external grooves of the inner cap member thus securing the interlocking member to the inner cap member. The outer cap member includes grooves on an inner circumferential wall which mate and engage with the pins of the interlocking member. When in the upright position, the bottle cannot be opened (child-resistant mode) but when inverted, the interlocking member is moved and allows the bottle can be twisted and opened (non-child-resistant mode).
Further, U.S. Pat. No. 3,514,003 describes a two-piece closure having a selectably engageable locking device which is engaged or disengaged by axial movement of a collar member relative to a cap member. The cap and collar members have respective sets of teeth which interlock when the collar member is moved axially upwardly into its uppermost position. The neck of the bottle also includes teeth which engage the collar member when the collar member is in the uppermost position, thus preventing rotation of the closure. To unlock the closure, the collar member is slid downward and out of engagement with the cap member.
U.S. Pat. No. 5,148,931 describes a two-piece closure having two sets of axial channels on an inner cap and two sets of protrusions on an interior surface of an outer cap. The closure is opened by aligning the protrusions on the outer cap with the proper set of channels on the inner cap, pulling the outer cap up relative to the inner cap, and rotating the outer cap so as to interlock the outer and inner caps.
Additional patent literature that describes variable container closures includes U.S. Pat. No. 3,733,001 (Gach), U.S. Pat. No. 3,950,917 (Choksi et al), U.S. Pat. No. 4,393,977 (Willingham), U.S. Pat. No. 5,082,130 (Weinstein), U.S. Pat. No. 5,148,931 (Minh), U.S. Pat. No. 5,316,161 (Gargione), U.S. Pat. No. 6,085,920 (Moretti), U.S. Pat. No. 6,095,353 (Gargiulo et al), U.S. Pat. No. 6,802,427 (Miceli et al) and U.S. Pat. No. 7,111,746 (Miceli et al), and U.S. Pat. Appln. Publ. No. 2002/0027119 (Miceli et al).