Controlled-release Pellets Research Articles

Pharmaceutical Micropellets: A Multi-particulate Drug Delivery System

Abstract: The major target of Pharmaceutical Sciences is to design a successful and suitable dosage forms for effective therapy, considering individual patient needs and compliance. Development of new technology or development of new dosage form using the existing technology is growing in importance and attracting increased interest, as they are specifically effective at a comparably low dose. Pellets falling in the size range of 1-1000μm are of great interest in the pharmaceutical industry for a variety of reasons which are not only offer flexibility in dosage form design and development, but are also utilized to improve the safety and efficacy of bioactive agents. The most important factor responsible for the proliferation of pelletized products is the popularity of controlled release technology in the delivery of drugs. Moreover, controlled release pellets are less susceptible to dose dumping than the reservoir-type single unit formulations. In case of oral products these pellets solve difficult taste-masking problems, disperse freely in the gastro intestinal tract, invariably maximize drug absorption, reduce peak plasma fluctuations and minimize potential side effects without appreciably lowering drug bioavailability, and also reduce variations in gastric emptying rate and overall transit time, thus, intra and inter subject variability of plasma profiles, which are common with single unit regimens, are minimized.

A systematic approach for assessing the suitability of enteral feeding tubes for the administration of controlled-release pellet formulations

Enteral nutrition plays an important role for patients who are unable to properly swallow food. In such patients, enteral feeding tubes are often used, through which food, but often also oral medications, are administered. However, this can pose the risk of tube clogging. Compared to the administration of crushed tablets, multiparticulate dosage forms are often considered easier to administer and furthermore have the advantage of enabling the administration of even controlled-release preparations. The objective of this systematic study was to identify tube- and formulation-related factors that contribute to successful administration of coated pellet formulations via a variety of commercially available feeding tube devices. The suitability of enteral feeding tubes for the administration of controlled-release pellet formulations that differed in size and type of starter core and functional coating was investigated in a stepwise approach using a novel in vitro setup. Results of the study indicate that pellet diameter and inner diameter of the feeding tube are by no means reliable parameters for estimating the tube’s suitability for pellet administration, but that many other tube and formulation-related factors and combinations thereof must be considered to ensure safe and effective drug administration via enteral feeding tubes.

Demonstration of Advanced Data Mining Tools for Optimization of Pellets Employing Modified Extrusion-pelletization Technique

Background: The multi particulate drug delivery system is preferred due to its numerous advantages but the batch to batch consistency and to achieve desired physical properties are the major challenges in the formulation of such dosage form. Objective: The objective of the present study was to explore the concept of quality by design for the development of galantamine HBr controlled release pellets using a modified palletization technique. Methods: Compritol 888 and Ethocel were chosen as hydrophobic release retardants, while Avicel was chosen as pelletization aid. A compatibility study was conducted between the drug and excipients. Drug loaded extrudes were prepared by using a mixture of isopropyl alcohol, and dichloromethane. Before converting the wet extrudes into pellets, pregelatinized starch was sprinkled on them to improve the physical properties of the pellets. The pellets were characterized for size, shape, and flow. The critical evaluation parameter was the drug dissolution pattern in distilled water. The dissolution data were treated with advanced data mining techniques. The in-vivo profile was predicted employing pharmacokinetic parameters of the drug and in-vitro drug release data of optimized batch pellets. Results: The failure mode and effect analysis revealed that the amount of Compritol 888 ATO and Ethocel were the most critical formulation parameters. The results of FTIR and DSC revealed compatibility between the drug and the excipients. The spherical pellets exhibited good flow. The drug dissolution studies of the batches, prepared according to the central composite design, revealed modified drug release. Multiple regression analysis and analysis of variance were performed to identify statistically significant factors. Contour plots demonstrated the impact of the amount of Compritol 888 and ethyl cellulose. The Design-Expert software was used to identify optimized formulation. The predicted in-vivo plasma concentration-time profile revealed the modified drug release up to 12h. Conclusions: Compritol and Ethocel were able to retard the drug release up to 12 hrs in distilled water. The innovative finding of this study is the use of a dry binder (pregelatinized starch) to improve the characteristics of pellets. Other dry binders are expected to show a similar effect. The newer processing technique can be of use in the industry.

Hyperandrogenemia alters mitochondrial structure and function in the oocytes of obese mouse with polycystic ovary syndrome

Hyperandrogenemia in an obese PCOS mouse model results in altered glucose/insulin metabolism and mitochondrial structure and function in the oocytes, in part explaining adverse outcomes and inheritance patterns seen in PCOS. To study the oocyte quality by means of mitochondrial structure and function in a well-established classic PCOS mouse model. Animal study using an obese PCOS mouse model compared with control. Animal research facility in a tertiary care university hospital setting. C57/B6J mice. Three week old mice had subdermal implants of DHT controlled release pellet or placebo for 90 days. The mouse model was validated by performing glucose tolerance test, HbA1c levels, body weight and estrous cycle analyses. Oocytes were subsequently isolated and were used to investigate mitochondrial membrane potential, oxidative stress, lipid peroxidation, ATP production, mtDNA copy number, transcript abundance, histology and electron microscopy. Results showed glucose intolerance and hyperinsulinemia along with dysregulated estrus cycle. Analysis of the oocytes demonstrated impaired inner mitochondrial membrane function, increased ATP production and mtDNA copy number, altered RNA transcript abundance and aberrant ovarian histology. Electron microscopy of the oocytes showed severely impaired mitochondrial ultrastructure. The obese PCOS mouse model shows a decreased oocyte quality related to impaired mitochondrial function.

Measuring dissolution profiles of single controlled-release drug pellets

Many solid-dose oral drug products are engineered to release their active ingredients into the body at a certain rate. Techniques for measuring the dissolution or degradation of a drug product in vitro play a crucial role in predicting how a drug product will perform in vivo. However, existing techniques are often labor-intensive, time-consuming, irreproducible, require specialized analytical equipment, and provide only “snapshots” of drug dissolution every few minutes. These limitations make it difficult for pharmaceutical companies to obtain full dissolution profiles for drug products in a variety of different conditions, as recommended by the US Food and Drug Administration. Additionally, for drug dosage forms containing multiple controlled-release pellets, particles, beads, granules, etc. in a single capsule or tablet, measurements of the dissolution of the entire multi-particle capsule or tablet are incapable of detecting pellet-to-pellet variations in controlled release behavior. In this work, we demonstrate a simple and fully-automated technique for obtaining dissolution profiles from single controlled-release pellets. We accomplished this by inverting the drug dissolution problem: instead of measuring the increase in the concentration of drug compounds in the solution during dissolution (as is commonly done), we monitor the decrease in the buoyant mass of the solid controlled-release pellet as it dissolves. We weigh single controlled-release pellets in fluid using a vibrating tube sensor, a piece of glass tubing bent into a tuning-fork shape and filled with any desired fluid. An electronic circuit keeps the glass tube vibrating at its resonance frequency, which is inversely proportional to the mass of the tube and its contents. When a pellet flows through the tube, the resonance frequency briefly changes by an amount that is inversely proportional to the buoyant mass of the pellet. By passing the pellet back-and-forth through the vibrating tube sensor, we can monitor its mass as it degrades or dissolves, with high temporal resolution (measurements every few seconds) and mass resolution (700 nanogram resolution). As a proof-of-concept, we used this technique to measure the single-pellet dissolution profiles of several commercial controlled-release proton pump inhibitors in simulated stomach and intestinal contents, as well as comparing name-brand and generic formulations of the same drug. In each case, vibrating tube sensor data revealed significantly different dissolution profiles for the different drugs, and in some cases our method also revealed differences between different pellets from the same drug product. By measuring any controlled-release pellets, particles, beads, or granules in any physiologically-relevant environment in a fully-automated fashion, this method can augment and potentially replace current dissolution tests and support product development and quality assurance in the pharmaceutical industry.

Efficacy and welfare assessment of an encapsulated para-aminopropiophenone (PAPP) formulation as a bait-delivered toxicant for feral cats (Felis catus)

Abstract ContextFeral cats are invasive predators of small and medium-sized fauna throughout Australia. The only broad-scale population-management technique for feral cats currently available in Australia is poison baiting. As poison baits for feral cats must be surface-laid, this can lead to the unintended exposure of non-target species consuming the baits. Encapsulation of a toxin within a robust, controlled-release pellet implanted within the meat lure (the combination of which is termed the Curiosity® bait) substantially reduces the potential risk to non-target species. Para-aminopropiophenone (PAPP) has been shown to be an effective toxin to which cats are highly susceptible. AimsThe present study aimed to measure the efficacy of encapsulating PAPP toxin in a controlled-release pellet on feral cats in a pen situation and to document the observed behaviours through the toxication process. MethodsPen trials with captive cats were undertaken to document efficacy of encapsulating PAPP toxin in a controlled-release pellet and to assess the behaviours during toxicosis. These behaviours inform an assessment of the humaneness associated with the Curiosity bait using a published relative humaneness model. Key resultsThe trials demonstrated a 95% consumption of the toxic pellet and observed the pattern of behaviours exhibited during the intoxication process. There was a definitive delay in the onset of clinical signs and death followed at ~185min after the first definitive sign. The humaneness using the relative humaneness model was scored at ‘mild suffering’. ConclusionsThe encapsulating PAPP toxin in a controlled-release pellet for feral cats is effective. The feral cats display a range of behaviours through the toxication process, and these have been interpreted as mild suffering under the relative humaneness model. ImplicationsThe documented efficacy and behaviours of encapsulating PAPP toxin in a controlled-release pellet provides knowledge of how the PAPP toxin works on feral cats, which may assist in decision-making processes for conservation land managers controlling feral cats and whether to incorporate the use of the Curiosity® bait into existing management techniques.

A mechanistic understanding of compression damage to the dissolubility of coated pellets in tablets

Damage to the drug diffusion coat barrier of controlled release pellets by the compaction force when preparing multiple-unit pellet system tablets is a major concern. Previous studies have shown that pellets located at the tablet axial and radial peripheral surfaces were more susceptible to damage when compacted due to the considerable shear encountered at these locations. Hence, this study was designed to assess with precision the impact of pellet spatial position in the compact on the extent of coat damage by the compaction force via a single pellet in minitablet (SPIM) system. Microcrystalline cellulose (MCC) pellet cores were consecutively coated with a drug layer followed by a sustained release layer. Chlorpheniramine maleate was the model drug used. Using a compaction simulator, the coated pellets were compacted singly into 3 mm diameter SPIMs with MCC as the filler. SPIMs with individual pellets placed in seven positions were prepared. The uncompacted and compacted coated pellets, as SPIMs, were subjected to drug release testing. The dissolution results showed that pellets placed at the top-radial position were the most susceptible to coat damage by the compaction force, while pellets positioned within the minitablet at the middle and upper quadrant positions showed the least damage. The SPIM system was found to be effective at defining the extent of coat damage to the pellet spatial position in the compact. This study confirmed that coated pellets located at the periphery were more susceptible to damage by compaction, with pellets located at the top-radial position showing the greatest extent of coat damage. However, if the pellet was completely encrusted by the cushioning filler, coat damage could be mitigated. Further investigations were directed at how the extent of coat damage impacted drug release. Interestingly, small punctures were found to be most detrimental to drug release whilst coats with large surface cuts did not completely fail. A damaged pellet coat has some self-sealing ability and failure is not total. Thus, this study provides a deeper understanding of the consequence of coat damage to drug release when sustained release coated pellets are breached.

Self-Micro-Emulsifying Controlled Release of Eugenol Pellets: Preparation, In vitro/In vivo Investigation in Beagle Dogs.

This report aimed to formulate self-micro-emulsifying (SMEDDS) controlled-release pellets delivery system to improve aqueous solubility and in vivo availability of eugenol, a main constituent of clove oil with multiple pharmacological activities. The optimal formulation of eugenol-SMEDDS was eugenol: ethyl oleate: cremophor EL: 1, 2-propylene glycol at the ratio of 5:5:12:8. The SMEDDS were observed under transmission electron microscopy (TEM), and the size distribution was measured with dynamic laser light scatting (DLS). The particle size, index of dispersity (PDI), and zeta potential (Z-potential) were 68.8 ± 0.1nm, 0.285 ± 0.031, and - 11.62 ± 0.63mV, respectively. Eugenol-SMEDDS exhibited substantial increased in vitro dissolution compared with the free eugenol. The eugenol-SMEDDS sustained-release pellets (eugenol-SMEDDS-SR pellets) comprising of eugenol-SMEDDS, hydroxypropyl methylcellulose (HPMC), microcrystalline cellulose (MCC), and ethyl cellulose (EC) coats were obtained via extrusion spheronization technique. Consequently, the obtained pellets observed under scanning electron microscopy (SEM) showed spherical shape with smooth surface, desirable drug loading capacity (7.18 ± 0.17%), greater stability, and controlled release. Meanwhile, the oral test showed that bioavailability of eugenol in pellets was highly improved 23.6-fold to the free eugenol. Overall, these results suggested that the improvement of the oral bioavailability of eugenol-SMEDDS-SR could be due to the successful incorporation of the drug into SMEDDS.

Formulation and evaluation of almotriptan controlled release pellets

Abstract: The aim of the present study was to formulate and evaluate Almotriptan pellets. Almotriptan controlled release pellets were prepared by Solution layering technique by using croscarmellose and povidone in former case and three different polymers HPMC K 100, Ethyl cellulose and Eudragit RS 100 as rate controlling polymer in three different ratios like 1:1, 1:1.5 and 1:2 to achieve desired release in later case. Evaluation was performed according to the Pharmacopoeia standards including Drug excipients compatibility, Percentage yield, Particle size distribution, Drug content analysis and in-vitro release study. The best results were found to be using Almotriptan and Eudragit RS 100 in 1:2 ratios. A broad variety of drug release pattern could be achieved by variation of polymers ratios which was optimized to match the target release profile. In comparison of in-vitro release studies for different controlled release formulations, F9 releases 98.54% of drug at the end of 12th hour and was considered as best formulation. Stability study has shown no significant change in the drug content analysis and in-vitro dissolution study of best formulation even after 6 months.
 Keywords: Almotriptan, Controlled release, Dissolution profile, in-vitro drug release, Stability studies.

Efficacy of dart-delivered PZP-22 immunocontraceptive vaccine in wild horses (Equus caballus) in baited traps in New Mexico, USA

Abstract Context Federally protected wild horses on public lands are undergoing population growth that overwhelms the historical management strategy of removal and adoption. Porcine zona pellucida (PZP) has been used as an injectable immunocontraceptive vaccine to induce reversible infertility in free-roaming horses. PZP vaccination during February and March, which is the optimal time for administering current vaccines, is not possible for the herd on Jarita Mesa Wild Horse Territory (JM WHT), New Mexico, due to severe weather, terrain and subject wariness. AimsThe first goal was to assess bait trapping and remote darting as a minimally disruptive alternative to helicopter gathers for treatment. The second goal was to quantify the efficacy over 2 years following spring treatment with a single injection of PZP-22 (a combination of PZP-adjuvant emulsion and controlled-release pellets) by remote dart delivery. Methods Bait trapping and dart delivery of PZP-22 was carried out on JM WHT from 4 April to 16 June 2012. The herd was observed in the summers of 2011, 2013 and 2014 to determine the foaling status of the study mares. Outcome (foal or no foal) as a function of treatment was analysed using Fisher’s exact test. Key resultsThere were 157 individuals, including 66 females >1 year old, documented in 2011. In 2012, 26 females (including three yearlings) identified by colour and markings were bait trapped and darted with PZP-22. The proportion of treated females foaling was lower than that of untreated females in 2013 and 2014, but the difference was only significant in 2013. Of the treated mares observed in 2013, the two that foaled were the last two treated in 2012. Untreated mares >4 years old were significantly more likely to foal than younger mares. Conclusions Bait trapping at JM WHT permitted successful delivery of PZP-22 in a previously inaccessible herd. Dart administration of PZP-22 in April–June induced at least 1 year of measurable infertility. Implications This is the first demonstration of the efficacy of an initial treatment of PZP-22 delivered by dart instead of hand injection. Considerations for PZP-22 treatment include seasonal timing of treatments and age of treated mares. Treatments need to take place early enough to allow antibody titers to build to contraceptive levels before the breeding season.

Paliperidone ascending controlled-release pellets with osmotic core and driven by delayed osmotic pressure

The aim of this work was to develop an ascending controlled-release pellet (ACRP) of paliperidone to improve poor solubility and provide a stable blood drug concentration. The inner core was produced by mixing different ratios of sodium chloride as an osmotic substance and microcrystalline cellulose (MCC) to offer a pressure drive when in contact with medium. After, the drug layer was processed by a liquid-layering method, with paliperidone ground to a nano-size in order to improve the solubility and modify the final release profile. Finally, in combination with an isolation layer and coating film, initial burst release could be prevented and the migration of medium was impeded. The results showed that due to the sustained-release film, the release of ACRP was less than 10% in the initial 4 h, and then up to 60% as the sodium chloride dissolved and provided an increasing pressure difference over the next 8 h, with an ascending rate similar to that of osmotic pump tablets, Invega, in pH 1.2 hydrochloric acid solution. The release profile of ACRP was most suitable for the DoseResp curve, and so the mechanism was explained by delayed osmotic pressure caused by the osmotic substance and nano-crystal reservoir controlled-membrane system.

Biopharmaceutical Process of Diclofenac Multi-particulate Systems for Chronotherapy of Rheumatoid Arthritis.

Diclofenac exhibits limited solubility, low bioabsorption and gastric toxicity. The objective of the study was to address the above limitations and to design a multi-particulate formulation for the chronotherapy of RA. Solid dispersions of DC with SSG and GG were prepared. Uniform-sized (∼400 µm) non-pareil seeds were coated with solid dispersions to produce immediate-release pellets (DMP-1 and DMP-2) and controlled-release pellets (DMP-3 and DMP-4). The resultant controlled-release pellets were further layered with methacrylate polymers to obtain pulsatile-release pellets (DMPP). Solubility, FTIR, DSC, micrometrics, SEM, drug content, drug release, pharmacokinetics, and stability studies were performed for DMPP. The solubility of DC was improved by 164-folds due to the presence of hydrophilic carriers in the solid dispersions. No chemical and physical interactions were noticed in FTIR spectra and also in thermograms. A fluidized bed processor facilitated the production of high-quality, circular, and regular pellets with an angle of repose less than 19.5 degrees and DC content between 95.18% and 98.87%. The maximum drug was released from DMPP at the end of 12 hours. DMP-1 and DMP-2 pellets had 2 hr of drug release and pulsatile, controlled-release pellets had a 6 hr lag phase followed by 12 hr controlled release. Both DMP-1 and DMP-2-immediate showed first-order release followed by Hixson-Crowell kinetics, whereas DMPP pellets followed zero-order release with Higuchi's kinetics. The maximum concentration of DC in plasma was 400.8 ng/mL at 5 hr for DMP-2 and 381.1 ng/mL at 14 hr for DMPP-5. The solubility of DC was increased with the application of solid dispersion and in turn increased the pharmacokinetics. The pellets were plausibly stable over a period of 90 days. Thus, multi-particulate pulsatile systems of DC were as effective as chronotherapeutics in the treatment of circadian rhythm-based ailments such as RA.

Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS): A rapid test for enteric coating thickness and integrity of controlled release pellet formulations

There are no rapid dissolution based tests for determining coating thickness, integrity and drug concentration in controlled release pellets either during production or post-production. The manufacture of pellets requires several coating steps depending on the formulation. The sub-coating and enteric coating steps typically take up to six hours each followed by additional drying steps. Post production regulatory dissolution testing also takes up to six hours to determine if the batch can be released for commercial sale. The thickness of the enteric coating is a key factor that determines the release rate of the drug in the gastro-intestinal tract. Also, the amount of drug per unit mass decreases with increasing thickness of the enteric coating. In this study, the coating process is tracked from start to finish on an hourly basis by taking samples of pellets during production and testing those using BARDS (Broadband Acoustic Resonance Dissolution Spectroscopy). BARDS offers a rapid approach to characterising enteric coatings with measurements based on reproducible changes in the compressibility of a solvent due to the evolution of air during dissolution. This is monitored acoustically via associated changes in the frequency of induced acoustic resonances. A steady state acoustic lag time is associated with the disintegration of the enteric coatings in basic solution. This lag time is pH dependent and is indicative of the rate at which the coating layer dissolves. BARDS represents a possible future surrogate test for conventional USP dissolution testing as its data correlates directly with the thickness of the enteric coating, its integrity and also with the drug loading as validated by HPLC.

Chronopharmacokinetic Evaluation of Budesonide Multiparticulate Systems.

Poor oral absorption of budesonide limits the design of its solid oral dosage form. With this context, multiparticulate pulsatile system of budesonide for chronotherapy of nocturnal asthma was aimed in this study. Initially, solid dispersions of budesonide (BD) using sodium starch glycolate (SSG) and guar gum (GG) were developed and characterized. Uniform sized non-pareil seeds (~400 µm) were coated with solid dispersions to obtain immediate (BMP) and controlled release pellets by solution layering technique. Rationale of selection of BD in this research was based on recent patents such as diltiazem HCl (US5914134) and multipar-ticulate systems (US5017381). Pulsatile drug release pellets (BMPP) of BD were obtained by coating the controlled release pellets with Eudragit L100 and RS 100. Pellets were assessed by saturation sol-ubility, FTIR, DSC, micromeritic, SEM, drug content, drug release, pharmacokinetic and stability studies. Solubility of BD was increased by 22 folds due to inter-particle distribution of BD and polymers in solid dispersions. No changes in characteristic functional groups of BD had indicated the compatibility of drug with polymers as noticed in FTIR and DSC. Fluidized bed processor enabled the production of spherical and uniformly distributed pellets with optimum angle of repose (12-19°) and friability (<1%). Solution layering technique employed in preparation of pellets had facilitated with moderately high BD content (91.5-99.6%) and 100% drug release at the end of 12hr. The pulsatile release pellets (BMPP) produced 6hr lag phase followed by 12hr controlled release. Promised pharmacokinetics was resulted as Cmax of 380ng/ml for BMP-2 and 162ng/ml for BMPP-5 and Tmax of 5 hr for BMP-2 and 12hr for BMPP-5. Increased pharmacokinetics was the direct results of increased solubility of BD due to application of solid dispersion and solution layering on pellets. Chronopharmacokinetics of BD were achieved with the help of Eudragit coatings on pellets. The BMP and BMPP formulations were found to be reasonably stable over a period of time. Thus, optimal chronopharmacokinetics of BD was achieved successfully by multiparticulate pulsatile technology.

Design and assessment of pulsatile technology based chronomodulated delivery systems of nifedipine

Nifedipine has poor aqueous solubility which limits its oral absorption as unit formulation. This limitation was acted through multiparticulate pulsatile systems for the treatment of angina pectoris. Initially, solid dispersions of nifedipine (NF) using sodium starch glycolate (SSG) and guar gum (GG) in 1:1 and 1:2 ratios were processed by kneading technique. Solution layering technique was employed to coat the solid dispersions on non-pareil sugar spheres (∼450 µm) to obtain immediate (NMP 1 and 2) and controlled release pellets (NMP-3 and 4). Controlled release pellets were further coated with Eudragit L100 and RS100 to achieve pulsatile pellets (NMPP-1 to 5). Pellets were subjected to saturation solubility, FTIR, DSC, micromeritics, SEM, drug content, drug release, pharmacokinetic and stability studies. By means of solid dispersions, solubility of NF was increased by 130-folds due to encompassing ordered interparticle mixing of NF and carriers. Significant interactions between NF and carriers were not demonstrated in FTIR spectra as well as in DSC thermograms. Fluidization process again proved its supremacy in producing defined spherical shaped pellets with desired micromeritics. Solution layering process resulted with high drug content (81–94.2%) and maximum drug was released by end of 12 h with 6 h lag phase. Suitable pharmacokinetic parameters were moderated by immediate (NMP) and pulsatile pellets (NMPP) as Cmax of 820 ng/mL for NMP-2 and 360.8 ng/mL for NMPP-5 at 5 and 16 h respectively. Increased pharmacokinetics and bioavailability were the result of linear increase in solubility of NF with solid dispersions. The pulsatile formulations were physicochemically intact over a period of time. Thus, multiparticulate systems of NF had demonstrated their applicability in chronotherapy of circadian based ailments.

Sclerostin activity plays a key role in the negative effect of glucocorticoid signaling on osteoblast function in mice

Stress during prenatal development is correlated with detrimental cognitive and behavioral outcomes in offspring. However, the long-term impact of prenatal stress (PS) and disrupted glucocorticoid signaling on bone mass and strength is not understood. In contrast, the detrimental effect of lead (Pb) on skeletal health is well documented. As stress and Pb act on common biological targets via glucocorticoid signaling pathways and co-occur in the environment, this study first sought to assess the combined effect of stress and Pb on bone quality in association with alterations in glucocorticoid signaling. Bone parameters were evaluated using microCT, histomorphometry, and strength determination in 8-month-old male mouse offspring subjected to PS on gestational days 16 and 17, lifetime Pb exposure (100 p.p.m. Pb in drinking water), or to both. Pb reduced trabecular bone mass and, when combined with PS, Pb unmasked an exaggerated decrement in bone mass and tensile strength. Next, to characterize a mechanism of glucocorticoid effect on bone, prednisolone was implanted subcutaneously (controlled-release pellet, 5 mg·kg−1 per day) in 5-month-old mice that decreased osteoblastic activity and increased sclerostin and leptin levels. Furthermore, the synthetic glucocorticoid dexamethasone alters the anabolic Wnt signaling pathway. The Wnt pathway inhibitor sclerostin has several glucocorticoid response elements, and dexamethasone administration to osteoblastic cells induces sclerostin expression. Dexamethasone treatment of isolated bone marrow cells decreased bone nodule formation, whereas removal of sclerostin protected against this decrement in mineralization. Collectively, these findings suggest that bone loss associated with steroid-induced osteoporosis is a consequence of sclerostin-mediated restriction of Wnt signaling, which may mechanistically facilitate glucocorticoid toxicity in bone.

Contraceptive efficacy of priming and boosting doses of controlled-release PZP in wild horses

Context At some sites, wild horse populations have been effectively and non-invasively regulated using remote darting with porcine zona pellucida (PZP) immunocontraceptive vaccines. However, this model has not been widely applied to wild horse herds in western USA, many of which are difficult to access because they roam large areas and are wary of people. Single-treatment, multi-year contraceptive vaccines would significantly broaden the scope for successful contraceptive management. Aims The aims of the present field studies were to (1) test the contraceptive effectiveness and longevity of primers incorporating PZP–adjuvant emulsions plus PZP and adjuvant in controlled-release pellets (‘PZP-22’); and (2) compare the contraceptive effectiveness and duration of PZP–adjuvant emulsion-only boosters with those of PZP-22 boosters when administered by hand or remote darting to PZP-22-primed mares. Methods Wild horses in herd management areas in Colorado and Utah, USA, were rounded up in 2008 and in Utah again in 2012. Previously untreated females received a single hand-injection of PZP–emulsion plus controlled-release PZP pellets (‘PZP-22’ vaccine) and were then released. In Autumn 2010, 50 Colorado females treated in 2008 were booster-darted with either the PZP-22 vaccine or the PZP emulsion alone. In Utah, 57 previously treated females rounded up in 2012 received hand-injections of either the PZP emulsion–pellet vaccine or the PZP emulsion alone. Maternity was established through field observation of nursing and other close associations. Key results Effectiveness of initial controlled-release PZP treatments over 2 years was low relative to previous trials. However, boosters delivered by dart or by hand to PZP-22-primed mares yielded high levels of contraceptive effectiveness for 3 years, with no consistent difference between simple PZP-emulsion boosters and boosters incorporating controlled-release pellets. Conclusions Priming mares with PZP-22 extends the efficacy of a subsequent PZP booster to at least 3 consecutive years. Implications Regulation of wild horse populations may be achieved with existing contraceptive agents by developing models and management plans that account for the increased longevity of repeated contraceptive treatments.

Testosterone replacement attenuates intimal hyperplasia development in an androgen deficient model of vascular injury

BackgroundAndrogen deficiency (AD) is associated with increased risk of vascular disease. Dysfunctional remodeling of the vessel wall and atypical proliferative potential of vascular smooth muscle cells (VSMCs) are fundamental processes in the development of intimal hyperplasia (IH). We have demonstrated an inverse relationship between dihydrotestosterone (DHT) levels, matrix metalloproteinase activity, and VSMC migration and proliferation in vitro. Here, we investigated the role of AD and testosterone (TST) replacement in IH development in an animal model of vascular injury to elucidate mechanisms modulated by AD that could be playing a role in the development of vascular pathogenesis. MethodsAged orchiectomized male rats underwent TST supplementation via controlled release pellet (0.5-35 mg). Young adult and middle-age adult intact (MI) and orchiectomized placebo (Plac) groups served as controls. All groups underwent balloon angioplasty of the left common carotid at a 14-d post-TST. Carotid tissue was collected at a 14-d post-balloon angioplasty and subjected to morphologic and immunohistochemical analyses. Human male VSMCs were treated with DHT (0-3000 nM) for 24 h then subjected to quantitative PCR for gene expression analyses and costained for F-actin and G-actin for visualization of cytoskeletal organization. ResultsI:M ratio was increased in Plac, subphysiological, low-physiological, and high pharmacologic level TST animals compared with MI controls but was decreased with high-physiological TST supplementation. Injury-induced expression of previously defined matrix metalloproteinase remodeling enzymes was not significantly affected by TST status. Urotensin (UTS) receptor (UTSR) staining was low in injured vessels of all young adult intact, MI, and Plac controls but was significantly upregulated in all groups receiving exogenous TST supplementation, irrespective of dose. In vitro DHT exposure increased the expression of UTSR in VSMCs in a dose-dependent manner. However, this did not correlate with any change in proliferative markers. F:G actin staining revealed that DHT-induced cytoskeletal organization in a dose-dependent manner. ConclusionsAD increased IH development in response to vascular injury, whereas physiological TST replacement attenuated this effect. AD-induced IH occurs independent of matrix remodeling mechanisms known to be heavily involved in vascular dysfunction, and AD alone does not affect the UTS and/or UTSR mechanism. Exogenous TST and/or DHT increases UTSR pathway signaling in vitro and in vivo. This modulation correlates to a shift in cytoskeletal organization and may exacerbate vasoconstrictive pathogenesis. While physiological TST replacement attenuates AD-modulated IH development, its UTS-mediated effect on vasotone may prove deleterious to overall vascular function.

High-throughput automated dissolution method applicable for a wide dose range of controlled release pellets

The aim of the present study was to demonstrate the application of an automated high-throughput (HT) dissolution method as a useful screening tool for characterization of controlled release pellets in the formulation development phase. Five controlled release pellet formulations with drug substances exhibiting high or low solubility were chosen to investigate the correlation of the automated HT dissolution method with the conventional dissolution testing. Overall, excellent correlations (R2 > 0.96) between the HT and the conventional dissolution method were obtained. In one case the initial unsatisfactory correlation (R2 = 0.84) and poor method agreement (SD = 12.5) was improved by optimizing the HT dissolution method with design of experiment approach. Here in comparison to initial experimental HT dissolution settings, increased amount of pellets (25% of the capsule filling mass), lower temperature (22 °C) and no shaking resulted in significantly better correlation (R2 = 0.97) and method agreement (SD = 5.3). These results show that such optimization is valuable for the development of HT dissolution methods. In conclusion, the high correlation of dissolution profiles obtained from the conventional and the automated HT dissolution method combined with low within-sample and measurement system variability, justifies the utilization of the automated HT dissolution method during development phase of controlled release pellets.

Ethylcellulose film coating of guaifenesin-loaded pellets: A comprehensive evaluation of the manufacturing process to prevent drug migration

The aim of the research was to investigate the complete process of pellet production in a Wurster fluidized bed coater in order to determine the main factors affecting the migration phenomenon of a soluble API through the ethycellulose film coating (Surelease®) and hence the long-term stability of the controlled release pellets. Guaifenesin (GFN), as BCS class I model drug, was layered on sugar spheres using a binder-polymer solution containing the dissolved GFN. The drug loaded pellets were then coated with Surelease®. The influence of drug loading (4.5–20.0% w/w), curing conditions (40–60°C and dynamic-static equipment), coating level (12–20% theoretical weight gain) and composition of the binder-layering solution (hypromellose versus Na alginate) on process efficiency (RSDW%), GFN content uniformity (RSDC%), GFN solid state (DSC and XRD) and pellet release profiles was evaluated. The effectiveness of the Surelease film was strongly affected by the ability of GFN to cross the coating layer and to recrystallize on the pellet surface. Results indicated that this behaviour was dependent on the polymer used in the binder-layering solution. Using hypromellose as polymer, GFN recrystallized on the coated pellet surface at both drug loadings. The curing step was necessary to stabilize the film effectiveness at the higher drug loading. Increasing the coating level delayed but did not prevent the GFN diffusion. Replacing hypromellose with Na alginate, reduced the migration of GFN through the film to a negligible amount even after six months of storage and the curing step was not necessary to achieve stable controlled release profiles over storage.