Aqueous disinfecting systems
Compositions effective as disinfecting solutions for ophthalmic devices such as contact lenses are provided. The compositions include a microbicide, preferably polyhexamethylene biguanide or alexidine, and a water soluble salt of a bis-aminopolyol, preferably 1,3-bis(tris[hydroxymethyl]methylamino)propane, as a buffering agent.
1. An aqueous solution for disinfecting a contact lens, comprising: from 0.1 to 10 ppm of a microbicide selected from the group consisting of polyhexamethylene biguanide and alexidine; and 0.001 to 0.2 mol/L of 1,3-bis(tris[hydroxylmethyl]methylamino)propane or a salt thereof as buffering agent, wherein the aqueous solution buffered by 1,3-bis(tris[hydroxylmethyl]methylamino)propane is characterized by having a disinfecting efficacy that is at least 1.0 log of reduction greater than a disinfecting solution containing the same amount of the microbiocide but buffered with a phosphate buffer, wherein said solution has a pH of 6.8 to 7.5.
2. The aqueous solution of claim 1 further comprising a chelating agent.
3. The aqueous solution of claim 2 wherein said chelating agent is selected from the group consisting of ethylene diamine tetraacetic acid, diethylene triamine pentaacetic acid, salts thereof, and mixtures thereof.
4. The aqueous solution of claim 1 further comprising a surfactant.
5. The aqueous solution of claim 4 wherein said surfactant is selected from the group consisting of poloxomers, poloxamines, octoxynol, hydroxylated castor oil, and tyloxapol.
6. The aqueous solution of claim 1 further comprising a tonicity agent.
7. The aqueous solution of claim 6 wherein said tonicity agent is sodium chloride.
8. The aqueous solution of claim 1 further comprising a viscosity modifying agent.
9. The aqueous solution of claim 8 wherein said viscosity modifying agent is selected from the group consisting of lecithin, hydroxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and methylcellulose, polyvinyl alcohol, and polyvinyl pyrolidone.