Formulations, liquid aqueous based

Microbiological protection of multiple-dose presentations such as liquid inhalations, nasal sprays, oral liquids, creams, and lotions is more complex. Once opened they are susceptible to microbiological contamination. If they are aqueous-based, they are in principle susceptible to proliferation of these new contaminants. To avoid this, they are formulated with antimicrobial agents or preservatives and are expected to be able to comply with preservative efficacy standards specified in the pharmacopeias. Preservative efficacy tests (not harmonized) are described in Section 51 of the USP and Section VIII. 14 of the PhEur (Fig. 3). 

For a good therapeutic effect the choice of the active substance and the choice of the vehicle are important. Physical and chemical factors play an important role. The solubility of the active substance in the vehicle and the concentration, the size of the molecule of the active substance, the partition between vehicle and skin, the particle size (in case of suspensions) and the nature of the vehicle (aqueous or lipid) determine the penetration speed and depth. Hydrocortisone, for example, is more lipid soluble in the ester form (hydrocortisone acetate). The latter will penetrate into the skin faster and more complete. Hydrocarbons, such as soft and liquid paraffin, release lipophilic active substances only very slowly and substances formulated in these bases will penetrate only in limited amounts into the skin. Fatty oils (vegetable oils, triglycerides) are able to pass into the upper layers of the skin. Penetration enhancers (salicylic acid, dimethyl sulfoxide, propylene glycol, urea) increase the penetration of active substances into the skin. 

This first liquid inks used for inkjet decoration met the basic requirements for fine droplets application such as low viscosity, moderate surface tension, a high color covering capacity, and nontoxic solvents. These early ink formulations were sometimes based on suspensions such as transition metal octanoates in octane or metal nitrate aqueous solutions corrected by polyglycols. Some ink patents for inkjet ceramic applications appeared in 2001 [59-61]. 

The first attempt at providing a mathematical formulation of the effect of scavengers on G-values in aqueous solution was made by Balkas et al. [38] based on an equation developed by Warman et al. [42] for scavenging of ion pairs in nonpolar liquids. Balkas et al. 

VARISOFT 222LM-(90%) is a more fluid and cold water dispersible version of VARISOFT 222-90%. It is designed to be used in the formulation of regular rinse, concentrated rinse, and high solids aqueous dispersions. Water at temperatures as low as 55F can be used to formulate these liquid rinse cycle fabric softeners. Its versatility simplifies inventory control of the base, yet offers much formulation flexibility. 

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