Tech Briefs

Exact Dose Dispensing Closure for Semi-Solids

This device replaces a conventional tube cap and enables a user to dispense an exact dose.

A novel closure technology now makes it possible to consistently squeeze an exact dose of semi-solids from a tube by means of a 180-degree rotating closure. It has potential uses in pharmaceutical transdermal and oral applications, as well as glue dispensing, semi-solid food dispensing, and paint dispensing. Other potential applications are exact dose dispensing of prescription toothpaste, food condiments, or cosmetic products such as sunscreen creams and skin care formulations.

altThe closure (see Figure 1) replaces the ordinary tube cap. It contains a chamber, with a tight-fitting small bead, that fills when the tube is squeezed. The semi-viscous substance pushes the bead towards one end of the chamber. By rotating the chamber 180 degrees, the bead then faces the tube. By squeezing the tube again, an exact dose is dispensed from the chamber by the bead moving towards the opposite end of the chamber, away from the tube. This charges the chamber again with another dose of exactly the same size. The bead, now pressing against the edge of the closure, furthest away from the tube, effectively closes the tube off. Al ter n a - tively, the closure can also be rotated through 90 degrees to close it off. In order to operate the closure, the user has to twist the closure in order to dispense a pre-determined dose from the tube.

altSemi-solids such as dental compounds often require dentists to mix exact dosages of two or more compounds just prior to application. Current means of measuring these dosages are cumbersome. With this technology, a closure could be placed on each dispensing tube that only allows the correct amount of compound to be dispensed.

This closure is designed to be disposed of with an empty tube. This is to prevent possible cross-contamination should the product be re-used. Best results are achieved when the closure is used with an aluminum or laminated plastic tube (see Figure 2). This is to prevent possible suck-back often experienced with normal unlaminated plastic tubes.

Three models of the closure currently exist:

  • The original design features a closure that can be affixed to any size tube, but can also be removed from the tube again. The closure serves as a cap for the tube, so no alternative cap is required. “Wings” for the closure can be affixed to the closure to make it easier to twist the chamber before and after dispensing. Attached to the bottom of the closure is a spacer that fits over the shoulders of the tube. This is an optional item, but allows for the branding of the closure.
  • An option is also available whereby the closure can be fitted to a tube, but cannot be removed thereafter. This effectively ensures that the closure is discarded along with the tube once the tube is empty or past its sell-by date.
  • The third option features a closure that dispenses a pre-determined amount in the process of opening the cap of the closure. This eliminates the need to twist the closure when dispensing a dose.