The present invention provides a safe hyaluronic acid base material that
is suitable for use in practical hyaluronic acid pharmaceutical
preparations capable of distribution at room temperature and having such
a low viscosity that injection is easy. The hyaluronic acid
pharmaceutical preparations can reside in a joint cavity for a prolonged
period of time while exhibiting analgesic effects. More specfically,
there is provide a hyaluronic acid modification product in which
hyaluronic acid and/or a pharmaceutically acceptable salt thereof is
bounded to a block polymer selected from PEO-PPO-PEO, PPO-PEO-PPO,
PEO-PLGA-PEO, PLGA-PEO-PLGA, PEO-PLA-PEO and PLA-PEO-PLA. The hyaluronic
acid modification product, despite capability of distribution at room
temperature and ease in handling because of the low viscosity, can have
its viscoelasticity rapidly increased after injection into a living body,
so that it is highly useful in treatment of joint diseases, aid in
surgical operation, repair of tissue, etc. as a main ingredient of novel
and practical hyaluronic acid pharmaceutical preparations.
