Preparation of carbon dioxide/propylene oxide/ε-caprolactone copolymers and their drug release behaviors

Pharmacokinetic-pharmacodynamic modeling approach for dose prediction of the optimal long-acting injectable formulation of finasteride

A controlled drug release formulation based on the subcutaneous injection of poly (lactic-co-glycolic acid) (PLGA) microspheres loaded with finasteride was prepared and evaluated for monthly delivery. After selection of biodegradable polymer and polymer-to-finasteride ratio, the formulation was characterized. Scanning electron microscopy (SEM) and laser-light particle size analysis were used to examine the morphology, surface structure, and particle size. High‑performance liquid chromatography (HPLC) was used to determine the drug loading, while liquid chromatography with tandem mass spectrometry (LC-MS/MS) was employed to analyze plasma finasteride concentrations. Results showed that the PLGA microspheres were spherical and of an appropriate size. The formulation stably releases the drug from the microspheres and the release sustained for a month without burst release, which was the desired duration. In vivo pharmacokinetic-pharmacodynamic (PK-PD) studies were conducted in beagle dogs through the administration of PROPECIA® (as a reference drug) per oral and subcutaneous injection of the long-acting injectable microsphere formulation (LAIF) loaded with five different doses of finasteride. From the acquired plasma data, PK-PD models for both PROPECIA®-administered group and LAIFs-injected groups were developed and validated. PK-PD profiles of both groups were predicted for up to one month. The predicted PK-PD profile of all LAIFs showed the achievability of monthly delivery and pharmacological effects without burst release, compared to the simulated PK-PD profile of PROPECIA®. According to the predicted PK-PD profiles, the formulation loaded with 16.8 mg of finasteride was determined to be the optimal dose. The data obtained from the PK-PD model could be used as the basis for the estimation of a first-in-human dose of the formulation.

Catalytic Chain Transfer Copolymerization of Propylene Oxide and CO2 using Zinc Glutarate Catalyst

Oligo and poly(propylene ether carbonate)-polyols with molecular weights from 0.8 to over 50 kg/mol and with 60-92 mol % carbonate linkages were synthesized by chain transfer copolymerization of carbon dioxide (CO2) and propylene oxide (PO) mediated by zinc glutarate. Online-monitoring of the polymerization revealed that the CTA controlled copolymerization has an induction time which is resulting from reversible catalyst deactivation by the CTA. Latter is neutralized after the first monomer additions. The outcome of the chain transfer reaction is a function of the carbonate content, i. e. CO2 pressure, most likely on account of differences in mobility (diffusion) of the various polymers. Melt viscosities of poly(ether carbonate)diols with a carbonate content between 60 and 92 mol % are reported as function of the molecular weight, showing that the mobility is higher when the ether content is higher. The procedure of PO/CO2 catalytic chain copolymerization allows tailoring the glass temperature and viscosity.

Development of finasteride polymer microspheres for systemic application in androgenic alopecia

The use of finasteride for alleviating hair loss has been investigated, and it has been applied as an oral dose medication. However, due to the inconvenience of daily drug administration over long period of time, novel controllable finasteride delivery has been actively investigated. As a novel method of finasteride delivery, the development of finasteride‑loaded microspheres for subcutaneous administration is becoming increasingly pharmaceutically important. Therefore, the present study aimed to use finasteride‑loaded microspheres in a controlled manner in an attempt to overcome the limitations of the oral administration of finasteride and to cause fewer adverse effects. Finasteride‑loaded microspheres containing poly(lactic‑co‑glycolic acid) and finasteride at a ratio of 4:1 were prepared, and a testosterone‑induced androgenic alopecia mouse model was used. Following observation for 10 weeks, the percentage hair growth was 86.7% (total hair growth 60%, partial hair growth 26.7%) in the orally‑applied finasteride‑treated group as a positive control, and 93.3% (total hair growth 60%, partial hair growth 33.3%) in the finasteride‑loaded microspheres‑treated group. Serum dihydrotestosterone levels began to decrease at week 6 in the orally‑applied finasteride‑ and finasteride‑loaded microsphere‑treated groups. In addition, the finasteride‑loaded microspheres‑treated group exhibited similar follicular number, follicular length, anagen/telogen ratio and hair bulb diameter values to those of the orally‑applied finasteride‑treated group. Furthermore, the finasteride‑loaded microspheres increased the activities of phosphoinositide 3‑kinase/protein kinase B and Wnt/β‑catenin in relation to hair follicle cell growth signaling in mouse skin, and suppressed the apoptosis of hair follicle cells by reducing the expression of transforming growth factor‑β2 and caspase‑3, which are indicators of apoptosis. In conclusion, the administration of a single injection of finasteride‑loaded microspheres was effective in treating testosterone‑induced alopecia. Furthermore, it led to equivalent hair growth effects when compared with orally‑applied finasteride, thus revealing the possibility of effective treatment via different routes of administration.

Collagen-coated polycaprolactone microparticles as a controlled drug delivery system

OBJECTIVE

Polycaprolactone (PCL) microparticles coated with acetylated collagen have been assessed for use as a controlled drug delivery system.

METHOD

The surface morphology, drug encapsulation and release profile of PCL microparticles and collagen-coated PCL microparticles containing doxycycline hydrochloride (DH) have been investigated in order to develop a controlled release system which would in addition act as a scaffold for cell attachment. PCL microparticles were prepared by emulsion solvent evaporation technique and loaded with DH. Since the encapsulation was found to be low, PCL microparticles were coated with acetylated collagen containing DH, to increase the drug availability. Collagen was modified by acetylation to shift its isoelectric point and to have acetylated collagen solution at pH 7.0. The microparticles were characterized using a scanning electron microscope (SEM) and the in vitro drug release profile was determined using HPLC.

RESULTS

Uniform sized (approximately 1000 nm) PCL microparticles were prepared using 4% PVA in the external water phase. Acetylated collagen at pH 7.0 was coated onto the PCL microparticles. This resulted in microparticles of uniform size at neutral pH. PCL acts as a support for collagen which acts as a scaffold for cell attachment. In vitro drug release studies show that collagen-coated PCL microparticle is a promising candidate for controlled drug delivery system having release duration of over 10 days. In vitro fibroblast culture studies reveal that collagen is a good substrate for cell attachment and would provide a stable environment for cell proliferation and regeneration. Thus, this system would be ideal for a short-term drug delivery to create an aseptic environment where cells can adhere and proliferate to regenerate the site.