Long-acting injectable hormonal dosage forms for contraception

Injectable systems for long-lasting insulin therapy

Insulin therapy is the mainstay to treat diabetes characterizedd by hyperglycemia. However, its short half-life of only 4-6 min limits its effectiveness in treating chronic diabetes. Advances in recombinant DNA technology and protein engineering have led to several insulin analogue products that have up to 42 h of glycemic control. However, these insulin analogues still require once- or twice-daily injections for optimal glycemic control and have poor patient compliance and adherence issues. To achieve insulin release for more than one day, different injectable delivery systems including microspheres, in situ forming depots, nanoparticles and composite systems have been developed. Several of these delivery systems have advanced to clinical trials for once-weekly insulin injection. This review comprehensively summarizes the developments of injectable insulin analogs and delivery systems covering the whole field of injectable long-lasting insulin technologies from prototype design, preclinical studies, clinical trials to marketed products for the treatment of diabetes.

Dissolving Microneedles Loaded with Gestodene: Fabrication and Characterization In Vitro and In Vivo

Background

Gestodene (GEST) is widely used in female contraception. It is currently being used as an oral contraceptive. However, unfortunately, oral contraceptives are often associated with several bothersome side effects and poor compliance. Therefore, a sustained delivery system for GEST to overcome these shortcomings is highly desirable.

Objectives

The present study successfully developed a kind of novel dissolving microneedles (DMNs) with a potential for sustained release and a minimally invasive intradermal treatment of GEST.

Methods

The dissolving microneedles containing GEST were fabricated using polyvinylpyrrolidone as the base material. The characteristics in vitro and pharmacokinetics in vivo of GEST-loaded DMNs were investigated.

Results

The results showed that the microneedle could pierce the porcine skin and release the drug at an average dose of 20µg/cm2 daily for seven days. The pharmacokinetic experiment of the microneedles indicated that the plasma level of GEST in rats increased with increasing drug dosage, and the plasma drug concentration-time curves were much flatter compared with subcutaneous injection and oral administration. In addition, no cutaneous irritation was observed.

Conclusions

GEST-loaded DMNs may be a promising intradermal sustained delivery system for contraceptive use.

Levonorgestrel Microneedle Array Patch for Sustained Release Contraception: Formulation, Optimization and In Vivo Characterization

Background: The goal of this work was to develop a levonorgestrel liposome-loaded microneedle array patch for contraception. Methods: Levonorgestrel-loaded liposome was formulated by a solvent injection technique, characterized, and studied. Results: The formulated liposomes were characterized for particle size (147 ± 8 nm), polydispersity index (0.207 ± 0.03), zeta potential (−23 ± 4.25 mV), drug loading (18 ± 3.22%) and entrapment efficiency (85 ± 4.34%). A cryo high-resolution transmission electron microscopy and cryo field emission gun scanning electron microscopy study showed spherical shaped particles with a smooth surface. The in vitro drug release and in vivo pharmacokinetic study showed sustained behaviour of Levonorgestrel for 28 days. Conclusion: The levonorgestrel liposome-loaded microneedle array patch showed better contraception than the drug-loaded microneedle array patch.

Coaxial electrospray of uniform polylactide core-shell microparticles for long-acting contraceptive

Despite its high efficacy and good patient compliance, the only long-acting injectable (LAI) contraceptive currently available in the US, depot medroxyprogesterone acetate (DMPA), is limited by significant side effects and a delayed return to fertility for up to 10 months after its intended duration of action. To overcome these limitations, we sought to develop an injectable poly(D,l-lactide) (PLA) microparticle for sustained release of contraceptive hormone, etonogestrel (ENG). A one-step technique, coaxial electrospray method was applied to prepare uniform ENG loaded core-shell structured and slow-degrading PLA microparticles (ENG-cs-MPs) to provide release control while minimizing polymer content. By adjusting voltage, polymer concentration and flow rate of the coaxial jetting solution, the prepared ENG-cs-MPs exhibited uniformly small particle size with volume mean diameter of 14.7 ± 0.5 μm and a shell thickness of 2.5 ± 0.1 μm, high drug loading of ~54%, high encapsulation efficiency of ~99%, and initial 1-day burst release of just ~10%. Long-term in vitro release of ENG was continuous for more than 3 months without change of the shell structure in 6 months. In PK studies, ENG-cs-MPs achieved a steady and continuous drug release for approximately 3 months and then quickly tapered off within 3 weeks. Hence, ENG-cs-MPs prepared by the coaxial electrospray method may be useful as a LAI contraceptive with an improved PK profile relative to DMPA.

Impact of jet pulverization and wet milling techniques on properties of aripiprazole long-acting injection and absorption mechanism research in vivo

This study aims to explore the influence of wet milling and jet pulverization on the aripiprazole microcrystalline long-acting injection. Crystal form and particle size distribution were taken as inspection indicators in vitro, and process parameters were optimized. The formulation prepared by wet milling (AMLAI-WM) was shown to undergo a slight conversion of crystal form by DSC, PXRD, TG, FT-IR and have a wider particle size distribution with D50 and Span values of 2.967 μm and 3.457 compared to the formulation fabricated by jet pulverization (AMLAI-JP) with 2.887 μm and 2.258 respectively. In addition, the in vitro release of AMLAI-WM was faster, whereby the pharmacokinetic data indicated that AMLAI-WM was absorbed more quickly within five days with AUC_0-5d of 5243.7 μg·L^-1·h and 4818.28 μg·L^-1·h, respectively. Furthermore, no statistically significant differences in C_max, t_max and AUC between AMLAI-JP and the commercial formulation (Abilify Maintena™) were found. The absorption mechanism was studied and showed a 1.4-fold later T_max after depletion of macrophages and significantly lower C_max and AUC after inhibiting angiogenesis, indicating inflammatory granuloma could facilitate drug plasma exposure. Overall, we demonstrated that jet pulverization was a good strategy for long-acting microcrystalline injection, and that the absorption behavior was affected by both particle size distribution and inflammatory granuloma.

Evaluating parameters affecting drug fate at the intramuscular injection site

Intramuscular (IM) injections are a well-established method of delivering a variety of therapeutics formulated for parenteral administration. While the wide range of commercial IM pharmaceuticals provide a wealth of pharmacokinetic (PK) information following injection, there remains an inadequate understanding of drug fate at the IM injection site that could dictate these PK outcomes. An improved understanding of injection site events could improve approaches taken by formulation scientists to identify therapeutically effective and consistent drug PK outcomes. Interplay between the typically non-physiological aspects of drug formulations and the homeostatic IM environment may provide insights into the fate of drugs at the IM injection site, leading to predictions of how a drug will behave post-injection in vivo. Immune responses occur by design after e.g. vaccine administration, however immune responses post-injection are not in the scope of this article. Taking cues from existing in vitro modelling technologies, the purpose of this article is to propose "critical parameters" of the IM environment that could be examined in hypothesis-driven studies. Outcomes of such studies might ultimately be useful in predicting and improving in vivo PK performance of IM injected drugs.

Impact of Formulation Parameters on In Vitro Release from Long-Acting Injectable Suspensions

The development of long-acting injectable (LAI) suspension products has increased in recent years. A better understanding of the relationship between the physicochemical properties of these products and their in vitro as well as in vivo performance is expected to further facilitate their development and regulatory review. Using Depo-SubQ Provera 104® as the reference listed drug (RLD), four qualitatively and quantitatively (Q1/Q2) equivalent LAI suspensions with different formulation properties were prepared. Two recrystallization methods (solvent evaporation and antisolvent) were utilized to obtain active pharmaceutical ingredient (API) with different properties and solid-state characterization was performed. In addition, two different sources of the major excipient were used to prepare the Q1/Q2 equivalent suspensions. Physiochemical characterization and in vitro release testing of the prepared Q1/Q2 equivalent suspension formulations and the RLD were conducted. In vitro drug release was dependent not only on the particle size, the morphology, and the crystallinity of the API but also on the residual solvent in the API. The excipient source also affected the drug release rates.

A New Long-Term Composite Drug Delivery System Based on Thermo-Responsive Hydrogel and Nanoclay

Several problems and limitations faced in the treatment of many diseases can be overcome by using controlled drug delivery systems (DDS), where the active compound is transported to the target site, minimizing undesirable side effects. In situ-forming hydrogels that can be injected as viscous liquids and jellify under physiological conditions and biocompatible clay nanoparticles have been used in DDS development. In this work, polymer-clay composites based on Pluronics (F127 and F68) and nanoclays were developed, aiming at a biocompatible and injectable system for long-term controlled delivery of methylene blue (MB) as a model drug. MB release from the systems produced was carried out at 37 °C in a pH 7.4 medium. The Pluronic formulation selected (F127/F68 18/2 wt.%) displayed a sol/gel transition at approx. 30 °C, needing a 2.5 N force to be injected at 25 °C. The addition of 2 wt.% of Na116 clay decreased the sol/gel transition to 28 °C and significantly enhanced its viscoelastic modulus. The most suitable DDS for long-term application was the Na116-MB hybrid from which, after 15 days, only 3% of the encapsulated MB was released. The system developed in this work proved to be injectable, with a long-term drug delivery profile up to 45 days.

A once-a-month oral contraceptive

Poor patient adherence to oral contraceptives is the predominant cause of failure of these therapies, leading to unplanned pregnancies that can negatively affect female health worldwide. To improve patient adherence, we developed an oral contraceptive that is administered once a month. Here, we describe the design and report in vivo characterization of a levonorgestrel-releasing gastric resident dosage form in pigs.

Assessment of Residual Solvent and Drug in PLGA Microspheres by Derivative Thermogravimetry

Thermogravimetry does not give specific information on residual organic solvents in polymeric matrices unless it is hyphenated with the so-called evolved gas analysis. The purpose of this study was to apply, for the first time, derivative thermogravimetry (DTG) to characterize a residual solvent and a drug in poly-d,l-lactide-co-glycolide (PLGA) microspheres. Ethyl formate, an ICH class 3 solvent, was used to encapsulate progesterone into microspheres. DTG provided a distinct peak, displaying the onset and end temperatures at which ethyl formate started to evolve from to where it completely escaped out of the microspheres. DTG also gave the area and height of the solvent peak, as well as the temperature of the highest mass change rate of the microspheres. These derivative parameters allowed for the measurement of the amount of residual ethyl formate in the microspheres. Interestingly, progesterone affected not only the residual solvent amount but also these derivative parameters. Another intriguing finding was that there was a linear relationship between progesterone content and the peak height of ethyl formate. The residual solvent data calculated by DTG were quite comparable to those measured by gas chromatography. In summary, DTG could be an efficient and practical quality control tool to evaluate residual solvents and drugs in various polymeric matrices.

Exploring Trehalose on the Release of Levonorgestrel from Implantable PLGA Microneedles

Hydrophobic drugs wrapped in poly (lactic-co-glycolic acid) (PLGA)-based microneedles (MNs) require a long time to release completely. To obtain the desired duration, it is still necessary to modulate the release of hydrophobic drugs from MNs, while the PLGA composition is unchangeable. In this work, implantable PLGA microneedles (IPMNs) composed of PLGA arrowheads encapsulating levonorgestrel (LNG) and a water-soluble supporting array were designed. We explored trehalose used as a porogen on the release of hydrophobic LNG from PLGA-based MNs. Varying the trehalose content in PLGA arrowheads could induce different rates of drug release. The highest cumulative release of LNG was 76.2 ± 3.9% for IPMNs with 33.3% trehalose during 21 days in vitro, while the cumulative release of LNG was 60.4 ± 3.5% for IPMNs without trehalose. Pharmacokinetic results in rats showed that plasma levels of LNG were sustained for 13 days for IPMNs with 33.3% trehalose and 16 days for IPMNs without trehalose. Furthermore, the PLGA arrowheads with trehalose degraded more rapidly than those without trehalose over 21 days in rats. Consequently, using trehalose as a porogen was a feasible approach to modulate the release of a hydrophobic drug from PLGA-based MNs.

ELQ-331 as a prototype for extremely durable chemoprotection against malaria

Background

The potential benefits of long-acting injectable chemoprotection (LAI-C) against malaria have been recently recognized, prompting a call for suitable candidate drugs to help meet this need. On the basis of its known pharmacodynamic and pharmacokinetic profiles after oral dosing, ELQ-331, a prodrug of the parasite mitochondrial electron transport inhibitor ELQ-300, was selected for study of pharmacokinetics and efficacy as LAI-C in mice.

Methods

Four trials were conducted in which mice were injected with a single intramuscular dose of ELQ-331 or other ELQ-300 prodrugs in sesame oil with 1.2% benzyl alcohol; the ELQ-300 content of the doses ranged from 2.5 to 30 mg/kg. Initial blood stage challenges with Plasmodium yoelii were used to establish the model, but the definitive study measure of efficacy was outcome after sporozoite challenge with a luciferase-expressing P. yoelii, assessed by whole-body live animal imaging. Snapshot determinations of plasma ELQ-300 concentration ([ELQ-300]) were made after all prodrug injections; after the highest dose of ELQ-331 (equivalent to 30 mg/kg ELQ-300), both [ELQ-331] and [ELQ-300] were measured at a series of timepoints from 6 h to 5½ months after injection.

Results

A single intramuscular injection of ELQ-331 outperformed four other ELQ-300 prodrugs and, at a dose equivalent to 30 mg/kg ELQ-300, protected mice against challenge with P. yoelii sporozoites for at least 4½ months. Pharmacokinetic evaluation revealed rapid and essentially complete conversion of ELQ-331 to ELQ-300, a rapidly achieved (< 6 h) and sustained (4–5 months) effective plasma ELQ-300 concentration, maximum ELQ-300 concentrations far below the estimated threshold for toxicity, and a distinctive ELQ-300 concentration versus time profile. Pharmacokinetic modeling indicates a high-capacity, slow-exchange tissue compartment which serves to accumulate and then slowly redistribute ELQ-300 into blood, and this property facilitates an extremely long period during which ELQ-300 concentration is sustained above a minimum fully-protective threshold (60–80 nM).

Conclusions

Extrapolation of these results to humans predicts that ELQ-331 should be capable of meeting and far-exceeding currently published duration-of-effect goals for anti-malarial LAI-C. Furthermore, the distinctive pharmacokinetic profile of ELQ-300 after treatment with ELQ-331 may facilitate durable protection and enable protection for far longer than 3 months. These findings suggest that ELQ-331 warrants consideration as a leading prototype for LAI-C.

Biodegradable Polymeric Injectable Implants for Long-Term Delivery of Contraceptive Drugs

Development of injectable, long-lasting, contraceptive drug delivery formulations and implants are highly desired to avoid unplanned pregnancies while improving patient compliance and reducing adverse side effects and treatment costs. The present study reports on the fabrication and characterization of two levonorgestrel (LNG) microsphere injectable formulations. Poly(ε-caprolactone) (PCL) with 12.5% and 24% (w/w) LNG were fabricated into microspheres, measuring 300±125 μm, via the oil-in-water (o/w) emulsion solvent evaporation technique. Formulations showed sustained drug release up to 120 days. FTIR, XRD, DSC, and TGA confirmed the absence of LNG chemical interaction with PCL as well as its molecular level distribution. The in vitro release of LNG was calculated to be Fickian diffusion controlled and properly characterized. The inclusion of multiple elevated release temperatures allowed for the application of the Arrhenius model to calculate drug release constants and representative sampling intervals, demonstrating the use of elevated temperatures for accelerated-time drug release studies.

Injectable In Situ Forming Depot Systems for Long-Acting Contraception

Up to date, no long-acting reversible contraceptive (LARC) is developed to be injectable through needles smaller than 18 G and can also provide contraception for more than 3 months after single injection. In this study, injectable polymeric in situ forming depot (ISD) systems are developed to have injectability through 21-23 G needles, and capability of sustained release of levonorgestrel (LNG) for at least 7 months in vitro and in vivo after single subcutaneous injection in rats. The systems are polymeric solutions composed of biodegradable poly(lactide-co-glycolide) and poly(lactic acid) polymers dissolved in a mixture of solvents like N-methyl-2-pyrrolidone and benzyl benzoate or triethyl citrate. LNG released from ISD systems successfully suppressed the estrous cycle of rats at plasma concentration above 0.35 ng mL^-1 . At the end of the treatment, when LNG plasma concentration drops down to be nondetectable, predictable return of fertility is observed in rats. The designed ISD systems have great potential to be further developed into robust injectable LARCs that can be injected through a 21 G or smaller needle and achieve a variety of contraception durations with high patient compliance and low cost.

Beyond conventional antibiotics - New directions for combination products to combat biofilm

Medical device related infections are a significant and growing source of morbidity and mortality. Biofilm formation is a common feature of medical device infections that is not effectively prevented or treated by systemic antibiotics. Antimicrobial medical device combination products provide a pathway for local delivery of antimicrobial therapeutics with the ability to achieve high local concentrations while minimizing systemic side effects. In this review, we present considerations for the design of local antimicrobial delivery systems, which can be facilitated by modeling local pharmacokinetics in the context of the target device application. In addition to the need for local delivery, a critical barrier to progress in the field is the need to incorporate agents effective against biofilm. This article aims to review key properties of antimicrobial peptides that make them well suited to meet the demands of the next generation of antimicrobial medical devices, including broad spectrum activity, rapid and biocidal mechanisms of action, and efficacy against biofilm.

An Accelerated Release Study to Evaluate Long-Acting Contraceptive Levonorgestrel-Containing in Situ Forming Depot Systems

Biodegradable polymer-based injectable in situ forming depot (ISD) systems that solidify in the body to form a solid or semisolid reservoir are becoming increasingly attractive as an injectable dosage form for sustained (months to years) parenteral drug delivery. Evaluation of long-term drug release from the ISD systems during the formulation development is laborious and costly. An accelerated release method that can effectively correlate the months to years of long-term release in a short time such as days or weeks is economically needed. However, no such accelerated ISD system release method has been reported in the literature to date. The objective of the current study was to develop a short-term accelerated in vitro release method for contraceptive levonorgestrel (LNG)-containing ISD systems to screen formulations for more than 3-month contraception after a single subcutaneous injection. The LNG-containing ISD formulations were prepared by using biodegradable poly(lactide-co-glycolide) and polylactic acid polymer and solvent mixtures containing N-methyl-2-pyrrolidone and benzyl benzoate or triethyl citrate. Drug release studies were performed under real-time (long-term) conditions (PBS, pH 7.4, 37 °C) and four accelerated (short-term) conditions: (A) PBS, pH 7.4, 50 °C; (B) 25% ethanol in PBS, pH 7.4, 50 °C; (C) 25% ethanol in PBS, 2% Tween 20, pH 7.4, 50 °C; and (D) 25% ethanol in PBS, 2% Tween 20, pH 9, 50 °C. The LNG release profile, including the release mechanism under the accelerated condition D within two weeks, correlated (r² ≥ 0.98) well with that under real-time conditions at four months.

Strengths, weaknesses, opportunities and challenges for long acting injectable therapies: Insights for applications in HIV therapy

Advances in solid drug nanoparticle technologies have resulted in a number of long-acting (LA) formulations with the potential for once monthly or longer administration. Such formulations offer great utility for chronic diseases, particularly when a lack of medication compliance may be detrimental to treatment response. Two such formulations are in clinical development for HIV but the concept of LA delivery has its origins in indications such as schizophrenia and contraception. Many terms have been utilised to describe the LA approach and standardisation would be beneficial. Ultimately, definitions will depend upon specific indications and routes of delivery, but for HIV we propose benchmarks that reflect perceived clinical benefits and available data on patient attitudes. Specifically, we propose dosing intervals of ≥1week, ≥1month or ≥6months, for oral, injectable or implantable strategies, respectively. This review focuses upon the critical importance of potency in achieving the LA outcome for injectable formulations and explores established and emerging technologies that have been employed across indications. Key technological challenges such as the need for consistency and ease of administration for drug combinations, are also discussed. Finally, the review explores the gaps in knowledge regarding the pharmacology of drug release from particulate-based LA injectable suspensions. A number of hypotheses are discussed based upon available data relating to local drug metabolism, active transport systems, the lymphatics, macrophages and patient-specific factors. Greater knowledge of the mechanisms that underpin drug release and protracted exposure will help facilitate further development of this strategy to achieve the promising clinical benefits.