Comparative in vitro release and clinical pharmacokinetics of leuprolide from Luphere 3M Depot, a 3-month release formulation of leuprolide acetate

A single-dose, randomized, open-labeled, parallel-group study comparing the pharmacokinetics, pharmacodynamics and safety of leuprolide acetate microspheres 3.75 mg and Enantone® 3.75 mg in healthy male subjects

Leuprolide acetate microspheres developed by Shanghai Livzon Pharmaceutical Co., Ltd. (T) have been marketed in China for more than 10 years, benefiting a large number of patients, and will continue to play an important role in China. However, as a generic drug, it is unclear whether there is a difference in efficacy between T and the original product Enantone^® (R). This study compared the differences in efficacy and safety of two 1-month depot formulations in 48 healthy Chinese male subjects by comparing multiple pharmacokinetic (PK) and pharmacodynamic (PD) parameters. The main research indicators were the PK parameters of leuprolide (C_max, AUC_0-t, AUC_0-D7, and AUC_D7-t) and the PD parameters of testosterone (E_max, AUEC_0-t, AUEC_0-D7, and AUEC_D7-t) after 42 days of administration. The C_max, AUC_0-t, AUC_0-D7 and AUC_D7-t of leuprolide were slightly higher in the T group than in the R group with 90% confidence intervals (CIs) of 94.43–118.53%, 109.13–141.88%, 109.53–139.54%, and 105.17–145.74%, respectively. No significant differences in the PD parameters (E_max, AUEC_0-t, AUEC_0-D7, and AUEC_D7-t) existed between the T and R groups, and 90% CIs were 62.80–93.57%, 88.17–110.55, 95.72%–118.50%, and 79.77–105.63, respectively. At 672 h (D28), the castration rate of T was 91.30% (21/23) and that of R was 60.87% (14/23). The PK characteristics were consistent and the inhibitory effects on testosterone levels were similar in both T and R groups; further, clinical safety was observed for both T and R formulations, suggesting that these two products can replace each other in clinical practice.

Clinical Trial Registration:http://www.chinadrugtrials.org.cn/clinicaltrials.searchlistdetail.dhtml, identifier CTR20200641.

Advances in encapsulating gonadotropin-releasing hormone agonists for controlled release: a review

Gonadotropin-releasing hormone (GnRH) agonists are peptides consisting of nine or ten amino acid residues. GnRH agonists have been applied in the therapy of sexual hormone disorders like prostate cancer, endometriosis, uterine myoma, central precious puberty, and in-vitro fertility. Treatment is achieved by continuous hormone intake and long-term agonists administration, which is usually associated with poor patient compliance. Because GnRH agonists that are administered with the parenteral route are broken down by peptidase, their half-life is short. As a result, developing sustained release for the drug delivery system is significant. Even though some drugs have been successfully delivered with long-acting release microspheres and approved by the Food and Drug Administration (FDA), some challenges remain. This review highlighted current approaches to encapsulate GnRH agonists into delivery systems and strategies encountered during the loading process. Moreover, the following sections provide strategies to improve the release profile, and animal and human studies were summarised.

New long-acting injectable microspheres prepared by IVL-DrugFluidic™ system: 1-month and 3-month in vivo drug delivery of leuprolide

The microspheres for 1-month (PLGA-based) and 3-month (PLA-based) drug releases of leuprolide were manufactured using an IVL-DrugFluidic™ system and their morphology, particle size and distribution, and encapsulation efficiency were compared with the commercialized products. In vivo test was also conducted to monitor the amount of leuprolide and testosterone in plasma after a single subcutaneous injection in male Sprague-Dawley (SD) rats and male Beagle dogs. The median diameter, span value, drug loading, and encapsulation efficiency of PLGA-based microspheres (63.29 μm, 0.26, 13.15%, and 78.90%, respectively) and PLA-based microspheres (80.28 μm, 0.21, 14.42%, and 86.50%, respectively) demonstrated narrow particle size distribution (monodispersed) and efficient drug loading/encapsulation efficiency. Both the microspheres exhibited a desired time-dependent drug release profile and reduced initial burst release by 16-fold in SD rats and 240-fold in Beagle dogs compared to Leuplin DPS®. Moreover, the testosterone level in plasma was suppressed to < 0.50 ng/mL after 28 days with a steady plasma drug concentration. The results suggested that newly developed leuprolide-loaded microspheres produced by the IVL-DrugFluidic™ system could provide extended drug release with advantages such as reduced initial burst release and testosterone level suppression, along with steady plasma drug concentration, over the existing products.

Recent Progress in Drug Release Testing Methods of Biopolymeric Particulate System

Biopolymeric microparticles have been widely used for long-term release formulations of short half-life chemicals or synthetic peptides. Characterization of the drug release from microparticles is important to ensure product quality and desired pharmacological effect. However, there is no official method for long-term release parenteral dosage forms. Much work has been done to develop methods for in vitro drug release testing, generally grouped into three major categories: sample and separate, dialysis membrane, and continuous flow (flow-through cell) methods. In vitro drug release testing also plays an important role in providing insight into the in vivo performance of a product. In vitro release test with in vivo relevance can reduce the cost of conducting in vivo studies and accelerate drug product development. Therefore, investigation of the in vitro-in vivo correlation (IVIVC) is increasingly becoming an essential part of particulate formulation development. This review summarizes the principles of the in vitro release testing methods of biopolymeric particulate system with the recent research articles and discusses their characteristics including IVIVC, accelerated release testing methods, and stability of encapsulated drugs.