AIM: The purpose of this analysis was to construct appropriate models to characterise population pharmacokinetics (PK) for PHA-794428 and PK/pharmacodynamics (PD) for the efficacy biomarker Insulin-like Growth factor-...AIM: The purpose of this analysis was to construct appropriate models to characterise population pharmacokinetics (PK) for PHA-794428 and PK/pharmacodynamics (PD) for the efficacy biomarker Insulin-like Growth factor-1 (IGF-1). METHODS: Fifty-six male healthy volunteers were enrolled into a clinical study. Subjects received in a randomised manner 3 subcutaneous injections over 3 periods: i) 3.6 mg recombinant human growth hormone (rhGH), ii) PHA-794428 0, 3, 10, 30, 60, 100, 300 or 500 μg/kg, and iii) PHA-794428 0, 10, or 30 μg/kg. Both PK and IGF-1 data were collected up to 336 h post-dose. The PK and PK/PD models were constructed in 3 stages: i) the PK model was developed, ii) the PK parameters were fixed during IGF-1 model building, iii) PK and IGF-1 data were analysed simultaneously. RESULTS: PHA-794428 exhibited non-linearity with respect to dose. A one-compartment disposition model with parallel linear and non-linear elimination most appropriately described the PHA-794428 serum concentrations versus time data. The absorption of PHA-794428 was characterised as a first-order process involving two absorption rate constants. The nonlinear elimination, characterised in terms of the maximal elimination capacity (Vmax=91.5 μg/h for 70 kg) and Michaelis-Menten constant (Km=73.9 μg/L) describing the concentration at which elimination is at half Vmax. The non-linear elimination pathway is approximately 10 times higher than the linear route (0.129 L/h). PHA-794428 has a limited distribution in the blood (V=4.4 L), due to its large molecular weight. Serum IGF-1 concentrations versus time data were best described by an indirect response model with PEG-hGH stimulating IGF-1 production rate. Drug effect was appropriately characterised by a maximum effect (Emax) model. The maximal IGF-1 production rate could increase up to 8-fold across the dose range studied. The PHA-794428 concentration at half Emax (EC50) is 56.5 ng/mL. A negative feedback loop was incorporated into the PK/IGF-1 model. The maximal inhibition (Imax) of IGF-1 on endogenous GH secretion was set to 100% and IC50, the IGF-1 concentration decreasing GH secretion by 50%, was 382 ng/mL. Placebo effect was negligible. CONCLUSION: Serum data of PHA-794428 and IGF-1 could be adequately described by PK and PK/IGF-1 models, which were successfully used to predict the doses and time course of PK and IGF-1 and study design for the subsequent clinical trials in adult patients with growth hormone deficiency (AGHD). PK/PD modelling and simulation demonstrated that PHA-794428 has a potential to return low IGF-1 levels to within the normal range by weekly dosing.展开更多
重组人生长激素(recombinant human growth hormone,rhGH)是改善身材矮小的有效治疗药物,目前rhGH可应用于包含生长激素缺乏症在内的多种原因导致的身材矮小,临床应用的扩展使其安全性问题备受关注。基于现有证据,当rhGH规范应用于生理...重组人生长激素(recombinant human growth hormone,rhGH)是改善身材矮小的有效治疗药物,目前rhGH可应用于包含生长激素缺乏症在内的多种原因导致的身材矮小,临床应用的扩展使其安全性问题备受关注。基于现有证据,当rhGH规范应用于生理性替代治疗时,其安全性较好。临床中,应用rhGH进行治疗期间可结合文献证据和临床经验重点关注短期安全性,长期安全性由于rhGH治疗时间不足尚无准确定论。该文梳理了在rhGH治疗过程中有可能出现的不良事件及其风险控制措施,旨在帮助临床医生了解rhGH治疗的整体安全性,改善临床规范化应用。展开更多
文摘AIM: The purpose of this analysis was to construct appropriate models to characterise population pharmacokinetics (PK) for PHA-794428 and PK/pharmacodynamics (PD) for the efficacy biomarker Insulin-like Growth factor-1 (IGF-1). METHODS: Fifty-six male healthy volunteers were enrolled into a clinical study. Subjects received in a randomised manner 3 subcutaneous injections over 3 periods: i) 3.6 mg recombinant human growth hormone (rhGH), ii) PHA-794428 0, 3, 10, 30, 60, 100, 300 or 500 μg/kg, and iii) PHA-794428 0, 10, or 30 μg/kg. Both PK and IGF-1 data were collected up to 336 h post-dose. The PK and PK/PD models were constructed in 3 stages: i) the PK model was developed, ii) the PK parameters were fixed during IGF-1 model building, iii) PK and IGF-1 data were analysed simultaneously. RESULTS: PHA-794428 exhibited non-linearity with respect to dose. A one-compartment disposition model with parallel linear and non-linear elimination most appropriately described the PHA-794428 serum concentrations versus time data. The absorption of PHA-794428 was characterised as a first-order process involving two absorption rate constants. The nonlinear elimination, characterised in terms of the maximal elimination capacity (Vmax=91.5 μg/h for 70 kg) and Michaelis-Menten constant (Km=73.9 μg/L) describing the concentration at which elimination is at half Vmax. The non-linear elimination pathway is approximately 10 times higher than the linear route (0.129 L/h). PHA-794428 has a limited distribution in the blood (V=4.4 L), due to its large molecular weight. Serum IGF-1 concentrations versus time data were best described by an indirect response model with PEG-hGH stimulating IGF-1 production rate. Drug effect was appropriately characterised by a maximum effect (Emax) model. The maximal IGF-1 production rate could increase up to 8-fold across the dose range studied. The PHA-794428 concentration at half Emax (EC50) is 56.5 ng/mL. A negative feedback loop was incorporated into the PK/IGF-1 model. The maximal inhibition (Imax) of IGF-1 on endogenous GH secretion was set to 100% and IC50, the IGF-1 concentration decreasing GH secretion by 50%, was 382 ng/mL. Placebo effect was negligible. CONCLUSION: Serum data of PHA-794428 and IGF-1 could be adequately described by PK and PK/IGF-1 models, which were successfully used to predict the doses and time course of PK and IGF-1 and study design for the subsequent clinical trials in adult patients with growth hormone deficiency (AGHD). PK/PD modelling and simulation demonstrated that PHA-794428 has a potential to return low IGF-1 levels to within the normal range by weekly dosing.
文摘重组人生长激素(recombinant human growth hormone,rhGH)是改善身材矮小的有效治疗药物,目前rhGH可应用于包含生长激素缺乏症在内的多种原因导致的身材矮小,临床应用的扩展使其安全性问题备受关注。基于现有证据,当rhGH规范应用于生理性替代治疗时,其安全性较好。临床中,应用rhGH进行治疗期间可结合文献证据和临床经验重点关注短期安全性,长期安全性由于rhGH治疗时间不足尚无准确定论。该文梳理了在rhGH治疗过程中有可能出现的不良事件及其风险控制措施,旨在帮助临床医生了解rhGH治疗的整体安全性,改善临床规范化应用。
