Chloramphenicol surfactant solubilization

TABLE 39.6 Parameters of the Solubilization of Chloramphenicol by Surfactants. Solubilization of chloramphenicol by surfactants... 

Surfactants The use of surfactants is greatly restricted in formulating ophthalmic solutions. The order of surfactant toxicity is anionic > cationic nonionic. Several nonionic surfactants are used in relatively low concentrations to aid in dispersing steroids in suspensions and to achieve or to improve solution clarity. Those principally used are the sorbitan ether esters of oleic acid (polysorbate or Tween 20 and 80), polymers of oxyethylated octyl phenol (tyloxapol), and polyoxyl 40 stearate. The lowest concentration possible is used to perform the desired function. Their effect on preservative efficacy and possible binding by macromolecules as well as effect on ocular irritation must be taken into account. The use of surfactants as cosolvents for an ophthalmic solution of chloramphenicol has been described (347). This composition includes polyoxyl 40 stearate and polyethylene glycol to solubilize 0.5% chloramphenicol. These surfactants-cosolvents provide a clear... 

FIGURE 39.6 Solubilization of chloramphenicol by surfactants. Squares, cetrimide black circles, sodium laurylsulfate empty circles, polysorbate 80 triangles, PEG 40 monostearate. 

The solubilization of chloramphenicol with one member each of four classes of surfactants is shown in Figure 39.6 while Table 39.6 gives the key parameters of the surfactants. 

The solubilization of chloramphenicol with one member each of four classes of surfactants is shown in Fig. 37.7, while Table 37.5 gives the respective parameters. The typically linear relationship in micellar solubilization is obvious in the graph Fig. 37.7. In Table 37.5, the respective data reflecting the solubilization power of the surfactants are presented. 

The surfactant in suspension formulations might minimize adhesional deposition by solubilization. Precipitation of chloramphenicol palmitate from solutions containing polysorbate 80 has been studied by Moes [50]. Low concentrations of the surfactant give coarse particles and large compact aggregates which on a macroscale have low sedimentation volumes. Systems with low concentrations of polysorbate 80 have higher apparent viscosities because of the aggregation of the particles. 

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