Evaluation of an Intravitreal Rho-Associated Kinase Inhibitor Depot Formulation in a Rat Model of Diabetic Retinopathy

Rho-associated kinase (ROCK) activation was shown to contribute to microvascular closure, retinal hypoxia, and to retinal pigment epithelium (RPE) barrier disruption in a rat model of diabetic retinopathy. Fasudil, a clinically approved ROCK inhibitor, improved retinal perfusion and reduced edema in this model, indicating that ROCK inhibition could be a promising new therapeutic approach for the treatment of diabetic retinopathy. However, due to its short intravitreal half-life, fasudil is not suitable for long-term treatment. In this study, we evaluated a very potent ROCK1/2 inhibitor (BIRKI) in a depot formulation administered as a single intravitreal injection providing a slow release for at least four weeks. Following BIRKI intravitreal injection in old Goto-Kakizaki (GK) type 2 diabetic rats, we observed a significant reduction in ROCK1 activity in the retinal pigment epithelium/choroid complex after 8 days and relocation of ROCK1 to the cytoplasm and nucleus in retinal pigment epithelium cells after 28 days. The chronic ROCK inhibition by the BIRKI depot formulation restored retinal pigment epithelial cell morphology and distribution, favored retinal capillaries dilation, and reduced hypoxia and inner blood barrier leakage observed in the diabetic retina. No functional or morphological negative effects were observed, indicating suitable tolerability of BIRKI after intravitreous injection. In conclusion, our data suggest that sustained ROCK inhibition, provided by BIRKI slow-release formulation, could be a valuable treatment option for diabetic retinopathy, especially with regard to the improvement of retinal vascular infusion and protection of the outer retinal barrier.

Nanomedicine potential for endometriosis treatment

Contraception has previously provided alternative medication delivery techniques for the treatment of endometriosis. Only LNG-IUSs and depot formulation (DMPA), however, have been studied in numerous RCTs to treat patients. These approaches tend to enhance patient compliance and satisfaction when compared to other conventional treatment alternatives. Nanotechnologies are potential new drug delivery techniques that have been shown to deliver compounds with a particular therapeutic impact. However, the information is limited and preliminary. Endometriosis research has identified the patients who could benefit most from this kind of medication administration. No one has ever been used in a clinical study to treat endometria. Alternative medication delivery techniques may help to enhance compliance, effectiveness, and the development of novel treatment approaches. The use of vaginal rings as a unique and alternative medication delivery route for AIs, as well as the experience with danazol, are examples. The vaginal ring has been studied as a new medication delivery mechanism for danazol and aromatase inhibitors. Nanotechnologies are made up of bioconjugates that deliver anti-inflammatory, antioxidant, anti-angiogenic, and immunomodulating chemicals directly to the illness site. At this early stage of proof-of-concept, the evidence is limited and tentative. Clinical effectiveness can not be predicted using mouse models.

Fertility of Women Treated during Childhood with Triptorelin (Depot Formulation) for Central Precocious Puberty: The PREFER Study

<b><i>Background:</i></b> Gonadotropin-releasing hormone analogues (GnRHa) administered as depot formulations are the standard of care for children with central precocious puberty (CPP). Puberty resumes after treatment discontinuation, but little is known concerning fertility in women who have been treated with GnRHa for CPP during childhood. <b><i>Methods:</i></b> The PREFER (PREcocious puberty, FERtility) study prospectively analysed fertility, via a series of questionnaires, in women treated during childhood with triptorelin (depot formulation) for CPP. Co-primary endpoints were the proportion of women wanting a pregnancy any time before study inclusion and during the follow-up period but not pregnant 6 and 12 months after stopping contraception and the waiting time to pregnancy (WTP). <b><i>Results:</i></b> A total of 574 women were identified, and 194 women were included in the analysis. Although there were not enough data for primary endpoint assessment, few women (1.7%) reported issues with fertility or were unable to become pregnant despite trying to conceive. Most pregnancies (84.4%, 95% CI [67.2–94.7%]) occurred within 1 year of trying to conceive, in line with the WTP for women without previous CPP. <b><i>Conclusion:</i></b> The results, based on a limited sample of patients, suggest that CPP treated with triptorelin does not negatively impact women’s fertility in adulthood. These results need to be consolidated with a subsequent study performed when these women will have reached their mid-thirties.

Novel Long-Acting Buprenorphine Medications for Opioid Dependence: Current Update

Opioid maintenance treatment with oral methadone or sublingual buprenorphine is the first-line treatment in opioid dependence. Three novel long-acting buprenorphine formulations have been approved or will be available soon: for subcutaneous weekly and monthly application, the depot formulations CAM 2038 (Buvidal®), the monthly depot formulation RBP-6000 (Sublocade™), and a 6-month buprenorphine implant (Probuphine™). Clinical data available so far on the efficacy of these 3 medications are given, and possible clinical implications are discussed.

Fasudil Loaded PLGA Microspheres as Potential Intravitreal Depot Formulation for Glaucoma Therapy

Rho-associated protein kinase (ROCK) inhibitors allow for causative glaucoma therapy. Unfortunately, topically applied ROCK inhibitors suffer from high incidence of hyperemia and low intraocular bioavailability. Therefore, we propose the use of poly (lactide-co-glycolide) (PLGA) microspheres as a depot formulation for intravitreal injection to supply outflow tissues with the ROCK inhibitor fasudil over a prolonged time. Fasudil-loaded microspheres were prepared by double emulsion solvent evaporation technique. The chemical integrity of released fasudil was confirmed by mass spectrometry. The biological activity was measured in cell-based assays using trabecular meshwork cells (TM cells), Schlemm’s canal cells (SC cells), fibroblasts and adult retinal pigment epithelium cells (ARPE-19). Cellular response to fasudil after its diffusion through vitreous humor was investigated by electric cell-substrate impedance sensing. Microspheres ranged in size from 3 to 67 µm. The release of fasudil from microspheres was controllable and sustained for up to 45 days. Released fasudil reduced actin stress fibers in TM cells, SC cells and fibroblasts. Decreased collagen gel contraction provoked by fasudil was detected in TM cells (~2.4-fold), SC cells (~1.4-fold) and fibroblasts (~1.3-fold). In addition, fasudil readily diffused through vitreous humor reaching its target compartment and eliciting effects on TM cells. No negative effects on ARPE-19 cells were observed. Since fasudil readily diffuses through the vitreous humor, we suggest that an intravitreal drug depot of ROCK inhibitors could significantly improve current glaucoma therapy particularly for patients with comorbid retinal diseases.

Injectable Lipid-Based Depot Formulations: Where Do We Stand?

The remarkable number of new molecular entities approved per year as parenteral drugs, such as biologics and complex active pharmaceutical ingredients, calls for innovative and tunable drug delivery systems. Besides making these classes of drugs available in the body, injectable depot formulations offer the unique advantage in the parenteral world of reducing the number of required injections, thus increasing effectiveness as well as patient compliance. To date, a plethora of excipients has been proposed to formulate depot systems, and among those, lipids stand out due to their unique biocompatibility properties and safety profile. Looking at the several long-acting drug delivery systems based on lipids designed so far, a legitimate question may arise: How far away are we from an ideal depot formulation? Here, we review sustained release lipid-based platforms developed in the last 5 years, namely oil-based solutions, liposomal systems, in situ forming systems, solid particles, and implants, and we critically discuss the requirements for an ideal depot formulation with respect to the used excipients, biocompatibility, and the challenges presented by the manufacturing process. Finally, we delve into lights and shadows originating from the current setups of in vitro release assays developed with the aim of assessing the translational potential of depot injectables.