Kinetic parameters Free-GHTHase PEG-GHTHase Enzyme injection  NADH Injection Enzyme injection  NADH Injection Initial Drug Conc. (U/ml)* 0.698 - 0.384 - Biological half-life time (h)** 10 9.6 12.2 12 Elimination Constant (U/h)*** 0.016 0.016 0.010 0.016

* IEC was expressed by the of initial enzyme activity U per volume of blood plasma of Zealand white rabbit (Approximately 85 ml/1.5 kg body weight). ** BT1/2 was the time (h), which the enzyme retains about 50 % of its original activity. *** Elimination constant was expressed by the rate of enzyme removal from the body

Table 3: in vivo Pharmacokinetic properties of free and PEG-GHTHase using New Zealand Rabbits.