ËÄÉ«AV

Poly(metaphosphoric acid) (PMA) and alkali metaphosphate complexes of .alpha.-6-deoxy-5-hydroxytetracycline (doxycycline) (I) were prepd. by reacting, I with PMA or its Na or K salt, resp. I derivs. such as its acid addn. salt may be substituted in the reaction. The 2 groups of complexes were distinguished by characteristic solubilities and ir peaks. Thus, 23.1 g I in 65 ml MeOH was added to 4.8 g PMA in 130 ml 1:1 CHCl3-MeOH. After stirring 2 g NaOH in 25 ml MeOH was added and pptn. was induced by adding Me2CHOH to give 21 g (C22H24N2O8)5(NaPO3).(HPO3)5 m.p. 187-92.degree.. Ten addnl. prepns. including phys. consts. and some comparative clin. blood level studies were described.