Tetracyclines solubilization

Naggar et al. [147] investigated the solubilization of the zwitterionic antibiotics tetracycline and oxytetracycline by polysorbate 20 and 80 at pH 5 and assumed that the interactions were due to some form of complexation which seems unlikely. A wider range of tetracyclines and their interactions with a non-ionic, anionic and cationic surfactant were studied by Ikeda et al [148] over a pH range of 2.1 to 5.6. It is unlikely that surfactant solutions of tetracycline are required, but the results are relevant in discussing tetracycline-surfactant interactions that could influence the activity of the antibiotic. Apparent partition coefficients of four tetracyclines in a polyoxyethylene (Brij 35) are shown in Table 6.14 obtained from dynamic dialysis measurements the interactions with ionic surfactants (Table 6.15) appear more complex. 

The tetracyclines have three macroscopic dissociation constants and thus their ionic behaviour is a complex function of pH. In the pH range of the solubilization... 

Water-solubilization. A 2% soln. of tetracycline in f erf-butanol treated with stoichiometric amounts of glyoxylic acid and pyrrolidine, stirred 0.5 hr. at 20 and 10 min. at reflux temp. —> product. Y 80%. - Various water-soluble derivatives of tetracycline can be prepared by this process. F. e. s. U. Valcavi et al., Farmaco, Ed. Sci. 21, 775 (1966). 

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