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. 2013 Aug;57(8):4001–4009. doi: 10.1128/AAC.00796-13

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.