Table 2.
Formulation attributes after long-term stability testinga
| Property | Prototype ZA/CG gel | Modified ZA/CG gel |
|---|---|---|
| Carrageenan content | 3.0% | 3.1% |
| Lambda/kappa carrageenan ratio | 95:5 | 60:40 |
| Buffer | None | 10 mM sodium acetate |
| Cosolvent | None | 2% propylene glycol |
| Zinc acetate content (13 to 15 mM) | 14 mM | 14 mM |
| Methyl paraben content (0.18 to 0.22 wt %) | 0.2 wt % | 0.2 wt % |
| pH (6.9 to 6.3) | 6.96 | 6.64 |
| Osmolality (350–500 mOs/kg) | NT | 428 |
| Viscosity, t = 0 (23,500 to 35,000 cP) | 25,300 cP | 28,800 cP |
| Viscosity (3 mos at 30°C/65% RH) | NT | 30,600 cP |
| Viscosity (6 mos at 30°C/65% RH) | NT | 33,300 cP |
| Viscosity (9 mos at 30°C/65% RH) | NT | 32,200 cP |
| Viscosity (12 mos at 30°C/65% RH) | NT | 34,300 cP |
| Viscosity (3 mos at 40°C/75% RH) | NT | 24,500 cP |
| Viscosity (6 mos at 40°C/75% RH) | NT | 24,800 cP |
| Viscosity (9 mos at 40°C/75% RH) | NT | 23,900 cP |
| Viscosity (1 mo at 50°C/ambient) | NT | 30,500 cP |
a
Formulations were placed in 30-ml polypropylene bottles. The bottles were capped and sealed and then stored at 30°C/65% RH, 40°C/75% RH, and 50°C/ambient humidity. The gels were analyzed at indicated times for pH, viscosity, osmolality, methyl paraben (MP) content, and zinc content. The acceptable ranges for each parameter are indicated in the Property column. All parameters stayed within specifications over 12 months at 30°C/65% RH, 9 months at 40°C/75% RH, and 1 month at 50°C/ambient humidity. NT, not tested.