RESUMEN
DMP 504, a highly cross-linked insoluble polymer, is a bile acid sequestrant developed by the DuPont Pharmaceuticals Company for serum cholesterol reduction. Since DMP 504 is insoluble, it was necessary to develop unique specific analytical methods to measure and control the quality of different lots of the drug. Since the mechanism of action of DMP 504 is believed to be by sequestration of bile acids, the in-vitro binding capacity of the polymer for cholic acid was chosen as a surrogate of in-vivo performance and used to assess potency of the compound. In this method, individual aliquots of DMP 504 at three different levels were incubated with a cholate solution of known concentration. The residual cholate solution was filtered and analyzed by a reversed-phase HPLC method using refractive index detection. When the bound cholate was plotted versus the mass of DMP 504, the resulting curve was linear. The slope of this curve is the cholate binding capacity of DMP 504. This method has been shown to be precise and robust. Precision of the method was shown to have an RSD of 2.0% with injection precision of 0.4% and stability of cholate solutions up to 73 h. It is also a unique binding capacity method due to its multi-point determination, and it has been shown to be a suitable quality control method for ensuring lot-to-lot consistency of drug substance.
Asunto(s)
Colatos/metabolismo , Polímeros/metabolismo , Compuestos de Amonio Cuaternario/metabolismo , Cromatografía Líquida de Alta Presión , Concentración de Iones de HidrógenoRESUMEN
The objective of these studies was to develop a leuprolide acetate depot based on an in situ forming drug delivery system (Atrigel(R)) to suppress the pituitary-gonadal axis and in turn the serum testosterone to chemical castration levels for a period of at least 3 months. Formulations with biodegradable lactide/glycolide copolymers that varied in molecular weight, lactide/glycolide ratio, and hydrophilicity were evaluated in rats for their efficacy by measuring serum testosterone levels. The effect of polymer irradiation was also investigated. Molecular weight of the polymers was characterized by gel-permeation chromatography, and retrieved implants at the termination of animal studies were assayed for residual drug content by high-performance liquid chromatography. These initial rat studies showed that a formulation containing a 75/25 lactide/glycolide copolymer dissolved in N-methyl-2-pyrrolidone with 3% w/w leuprolide acetate suppressed serum testosterone for a period of 3 months or longer. This formulation with its advantages of biodegradability, biocompatibility, ease of injection, and no need for removal after use should be beneficial in treating patients with hormonal-dependent prostate and mammary cancers, endometriosis, and precocious puberty. In addition, this formulation with its simple manufacturing process is expected to provide an economic benefit to the user compared with products currently available on the market.
Asunto(s)
Implantes de Medicamentos , Leuprolida/farmacología , Hipófisis/efectos de los fármacos , Testículo/efectos de los fármacos , Animales , Cromatografía Líquida de Alta Presión , Leuprolida/administración & dosificación , Masculino , Ratas , Ratas Sprague-Dawley , Testosterona/sangreRESUMEN
The objective of this study was to evaluate the formulation parameters critical to the efficacy of an injectable polymeric implant of leuprolide acetate, formed in situ, in suppressing and maintaining serum testosterone levels of animals in the range 0.5 ng/ml for over 90 days. The formulation evaluated contained 45% (w/w) 75/25 poly (DL-lactide-co-glycolide) polymer having an intrinsic viscosity of 0.20 dl/g, dissolved in 55% (w/w) N-methyl-2-pyrrolidone with 3% (w/w) leuprolide acetate added either as a homogeneous solution or a two-part suspension (A/B) system, in which the drug was dispersed within the polymer solution immediately prior to use. The formulation parameters evaluated in this study included polymer molecular weight, polymer concentration, and drug loading. Both rat and dog models were used to evaluate efficacy. Serum testosterone was assayed by radioimmunoassay to determine efficacy, and retrieved implants from the rats at the termination of the study were analyzed by HPLC for residual drug content to determine the extent of drug release. With the candidate formulation, testosterone levels in dogs diminished to the targeted levels of 0. 5 ng/ml by day 14 and remained suppressed up to day 91, reproducing the results seen in rats. Variations in polymer concentration (40-50%), and drug load (3-6% (w/w)) did not have a significant effect on the apparent level and duration of efficacy. However, employing lower molecular weight polymer decreased the duration of efficacy of the formulation.
Asunto(s)
Leuprolida/administración & dosificación , Animales , Preparaciones de Acción Retardada , Perros , Implantes de Medicamentos , Humanos , Ácido Láctico/administración & dosificación , Leuprolida/farmacología , Masculino , Ácido Poliglicólico/administración & dosificación , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Polímeros/administración & dosificación , Ratas , Ratas Sprague-Dawley , Suspensiones , Testosterona/sangreRESUMEN
The primary objective of this study was to evaluate the effect of drug loading on the release of leuprolide acetate from an injectable polymeric implant, formed in situ, and efficacy of the released drug in suppressing serum testosterone levels in dogs for at least 90 days. An additional objective was to compare the optimum implant formulation with a commercial microsphere product. Evaluated implant formulations contained 45% w/w 75/25 poly (DL-lactide-co-glycolide) polymer having an intrinsic viscosity of 0.20 dL/g, dissolved in N-methyl-2-pyrrolidone. Irradiated polymer solution was mixed with leuprolide at different drug loads (3%, 4.5%, and 6% w/w) prior to subcutaneous administration to dogs. Dog serum was analyzed for testosterone (RIA) and leuprolide (LC/MS/MS) levels and comparisons within the three implant formulation groups were made. Varying the drug load did not significantly affect the release of leuprolide or efficacy of the implant formulation. Thus, the 6% w/w formulation with the smaller injection volume was selected for comparison with the commercial LUPRON Depot product, which was administered intramuscularly at a similar dosage. These comparisons of serum testosterone and leuprolide levels showed no significant difference in the pharmacologic efficacy even though drug levels were different at a number of points. This was mainly due to associated high standard deviations. Based on these studies, the 6% w/w leuprolide implant formulation was considered to be a suitable candidate for further development. Additional benefits of this system include its simple manufacturing and lower costs.
Asunto(s)
Leuprolida/metabolismo , Leuprolida/farmacología , Polímeros/química , Prótesis e Implantes , Animales , Preparaciones de Acción Retardada/química , Preparaciones de Acción Retardada/metabolismo , Preparaciones de Acción Retardada/farmacología , Perros , Implantes de Medicamentos/química , Fármacos para la Fertilidad Femenina/química , Fármacos para la Fertilidad Femenina/metabolismo , Fármacos para la Fertilidad Femenina/farmacología , Leuprolida/sangre , Leuprolida/química , Masculino , Peso Molecular , Testosterona/sangreRESUMEN
DMP 504 is a high molecular weight polymer currently under development by The DuPont Merck Pharmaceutical Company as a novel bile acid sequestrant to lower serum cholesterol. To assess its safety, DMP 504 is incorporated into rodent diet for oral administration to rats and mice. An analytical method was developed to determine the accuracy and homogeneity of the blends. Since a physical separation or extraction of DMP 504 from the diet was not feasible, near-infrared spectroscopy (near-IR) was employed. The near-IR method provides accurate and precise results for blends containing 1.5-8.0% of DMP 504. Comparison of results at the 1.5% level with a cholate binding referee method is also presented. Both methods provided equivalent results for the 1.5% level.