Slow-release Formulation Research Articles

Donepezil for dementia due to Alzheimer's disease.

Background Alzheimer's disease is the most common cause of dementia in older people. One of the aims of therapy is to inhibit the breakdown of a chemical neurotransmitter, acetylcholine, by blocking the relevant enzyme. This can be done by a group of chemicals known as cholinesterase inhibitors. Objectives The objective of this review is to assess whether donepezil improves the well-being of patients with dementia due to Alzheimer's disease. Search methods The Cochrane Dementia and Cognitive Improvement Group's Specialized Register was searched using the terms 'donepezil', 'E2020' and 'Aricept' on 5 April 2006. This Register contains up-to-date records of all major health care databases and many ongoing trial databases. Members of the Donepezil Study Group and Eisai Inc were contacted. Selection criteria All unconfounded, double-blind, randomized controlled trials in which treatment with donepezil was compared with placebo for patients with mild, moderate or severe dementia due to Alzheimer's disease. Data collection and analysis Data were extracted by one reviewer (JSB), pooled where appropriate and possible, and the pooled treatment effects, or the risks and benefits of treatment estimated. Main results 24 trials are included, involving 5796 participants, of which 15 reported results in sufficient detail for the meta-analyses. Most trials were of 6 months or less duration in selected patients. Patients in 20 trials had mild to moderate disease, in two trials moderate to severe, and in two severe disease. Available outcome data cover domains including cognitive function, activities of daily living, behaviour, global clinical state, adverse events and health care resource costs. For cognition there is a statistically significant improvement for both 5 and 10 mg/day of donepezil at 24 weeks compared with placebo on the ADAS-Cog scale (-2.01 points MD, 95%CI -2.69 to -1.34, P < 0.00001); -2.80 points, MD 95% CI -3.74 to -2.10, P < 0.00001) and for 10 mg/day donepezil compared with placebo at 24 weeks (5.55 SIB points, 95% CI 3.60 to 7.49, p<0.00001) and 52 weeks (1.84 MMSE points, 95% CI, 0.53 to 3.15, P =0.006). The results show some improvement in global clinical state (assessed by a clinician) in people treated with 5 and 10 mg/day of donepezil compared with placebo at 24 weeks for the number of patients showing improvement (OR 2.38, 95% CI 1.78 to 3.19, P = < 0.00001, OR 1.82, 95% CI 1.42 to 2.35, P < 0.00001). Benefits of treatment were also seen on measures of activities of daily living and behaviour, but not on the quality of life score. There were significantly more withdrawals before the end of treatment from the 10 mg/day (289/1125 24% 10 mg/day vs 219/1079 20% placebo, OR 1.35, 95% CI 1.11 to 1.65, P = 0.003) but not the 5 mg/day, (100/561 18% 5 mg/day vs 109/568 19% placebo, OR 0.91, 95% CI 0.68 to 1.24, P = 0.56) donepezil group compared with placebo which may have resulted in some overestimation of beneficial changes at 10 mg/day. Benefits on the 10 mg/day dose were marginally larger than on the 5 mg/day dose. The results were similar for all severities of disease. Two studies presented results for health resource use, and the associated costs. There were no significant differences between treatment and placebo for any item, the cost of any item, and for the total costs, and total costs including the informal carer costs. Many adverse events were recorded, with more incidents of nausea, vomiting, diarrhoea, muscle cramps, dizziness, fatigue and anorexia (significant risk associated with treatment) in the 10 mg/day group, compared with placebo. There were more incidents of anorexia, diarrhoea, and muscle cramps in the 5 mg/day group compared with placebo, but not of dizziness, fatigue, nausea or vomiting. Very few patients left a trial as a direct result of the intervention. Authors' conclusions People with mild, moderate or severe dementia due to Alzheimer's disease treated for periods of 12, 24 or 52 weeks with donepezil experienced benefits in cognitive function, activities of daily living and behaviour. Study clinicians rated global clinical state more positively in treated patients, and measured less decline in measures of global disease severity. There is some evidence that use of donepezil is neither more nor less expensive compared with placebo when assessing total health care resource costs. Benefits on the 10 mg/day dose were marginally larger than on the 5 mg/day dose. Taking into consideration the better tolerability of the 5 mg/day donepezil compared with the 10 mg/day dose, together with the lower cost, the lower dose may be the better option. The debate on whether donepezil is effective continues despite the evidence of efficacy from the clinical studies because the treatment effects are small and are not always apparent in practice.

Inhaled Treprostinil-Prodrug Lipid Nanoparticle Formulations Provide Long-Acting Pulmonary Vasodilation.

Treprostinil (TRE), a prostanoid analogue approved in the USA for the treatment of pulmonary arterial hypertension, requires continuous infusion or multiple dosing sessions per day for inhaled and oral routes of administration due to its short half-life. The inhaled drug is known to induce adverse systemic and local effects including headache, nausea, cough, and throat irritation which may be due at least in part to transiently high drug concentrations in the lungs and plasma immediately following administration [1]. To ameliorate these side effects and reduce dosing frequency we designed an inhaled slow-release TRE formulation. TRE was chemically modified to be an alkyl prodrug (TPD) which was then packaged into a lipid nanoparticle (LNP) carrier. Preclinical screening in a rat model of hypoxia-induced pulmonary vasoconstriction led to selection of a 16-carbon alkyl ester derivative of TRE. The TPD-LNP demonstrated approximately 10-fold lower TRE plasma Cmax compared to inhaled TRE solution while maintaining an extended vasodilatory effect. The favorable PK profile is attributed to gradual dissociation of TPD from the LNP and subsequent conversion to TRE. Together, this sustained presentation of TRE to the lungs and plasma is consistent with a once- or twice-daily dosing schedule in the absence of high Cmax-associated adverse events which could provide patients with an improved treprostinil therapy.

The Expanding Therapeutic Utility of Botulinum Neurotoxins.

Botulinum neurotoxin (BoNT) is a major therapeutic agent that is licensed in neurological indications, such as dystonia and spasticity. The BoNT family, which is produced in nature by clostridial bacteria, comprises several pharmacologically distinct proteins with distinct properties. In this review, we present an overview of the current therapeutic landscape and explore the diversity of BoNT proteins as future therapeutics. In recent years, novel indications have emerged in the fields of pain, migraine, overactive bladder, osteoarthritis, and wound healing. The study of biological effects distal to the injection site could provide future opportunities for disease-tailored BoNT therapies. However, there are some challenges in the pharmaceutical development of BoNTs, such as liquid and slow-release BoNT formulations; and, transdermal, transurothelial, and transepithelial delivery. Innovative approaches in the areas of formulation and delivery, together with highly sensitive analytical tools, will be key for the success of next generation BoNT clinical products.

COMPARATIVE IN VITRO EVALUATION OF DIFFERENT BRANDS OF NIFEDIPINE 20mg RETARD TABLET PRODUCTS MARKETED IN ADDIS ABABA, ETHIOPIA

Nifedipine has been formulated and marketed as extended-release-film coated tablet. A certain degree of success has been achieved in reducing the incidence of adverse effects by the use of slow-release formulations such as nifedipine retard. The aim of the present study was to evaluate the physicochemical quality attributes and in vitro equivalence of six brands of nifedipine retard tablets available in different retail outlets in Addis Ababa, Ethiopia. After constructing the calibration curve, the in vitro drug release studies were carried out using USP type I dissolution apparatus at 100 rpm. The dissolution was done in a medium of 0.1N HCl containing 0.5% sodium lauryl sulfate for 12 hrs. All the tablets met the requirement for tablet weight uniformity. The mean crushing strengths of sample tablets ranged from 49.2 to 111.2 N. All the brands studied released more than 80% within 12 hours which is within the tolerance limit.  However the release profile revealed that five of the brands showed over 15% drug release at 1st hour except product F which released only 14.32%. In conclusion, all the brands of tablets had uniform thickness and good hardness. Despite all the brands could sustained the release for over 12 hours recommended for such formulations, five of them showed higher release in the first hour which may affect their in vivo performance.” Keywords: nifedipine, retard tablets, physicochemical properties, crushing strengths, in vitro drug release

Targeting cattle for malaria elimination: marked reduction of Anopheles arabiensis survival for over six months using a slow-release ivermectin implant formulation

BackgroundMosquitoes that feed on animals can survive and mediate residual transmission of malaria even after most humans have been protected with insecticidal bednets or indoor residual sprays. Ivermectin is a widely-used drug for treating parasites of humans and animals that is also insecticidal, killing mosquitoes that feed on treated subjects. Mass administration of ivermectin to livestock could be particularly useful for tackling residual malaria transmission by zoophagic vectors that evade human-centred approaches. Ivermectin comes from a different chemical class to active ingredients currently used to treat bednets or spray houses, so it also has potential for mitigating against emergence of insecticide resistance. However, the duration of insecticidal activity obtained with ivermectin is critical to its effectiveness and affordability.ResultsA slow-release formulation for ivermectin was implanted into cattle, causing 40 weeks of increased mortality among Anopheles arabiensis that fed on them. For this zoophagic vector of residual malaria transmission across much of Africa, the proportion surviving three days after feeding (typical mean duration of a gonotrophic cycle in field populations) was approximately halved for 25 weeks.ConclusionsThis implantable ivermectin formulation delivers stable and sustained insecticidal activity for approximately 6 months. Residual malaria transmission by zoophagic vectors could be suppressed by targeting livestock with this long-lasting formulation, which would be impractical or unacceptable for mass treatment of human populations.

The Science of Local Anesthesia: Basic Research, Clinical Application, and Future Directions.

Local anesthetics have been used clinically for more than a century, but new insights into their mechanisms of action and their interaction with biological systems continue to surprise researchers and clinicians alike. Next to their classic action on voltage-gated sodium channels, local anesthetics interact with calcium, potassium, and hyperpolarization-gated ion channels, ligand-gated channels, and G protein-coupled receptors. They activate numerous downstream pathways in neurons, and affect the structure and function of many types of membranes. Local anesthetics must traverse several tissue barriers to reach their site of action on neuronal membranes. In particular, the perineurium is a major rate-limiting step. Allergy to local anesthetics is rare, while the variation in individual patient's response to local anesthetics is probably larger than previously assumed. Several adjuncts are available to prolong sensory block, but these typically also prolong motor block. The 2 main research avenues being followed to improve action of local anesthetics are to prolong duration of block, by slow-release formulations and on-demand release, and to develop compounds and combinations that elicit a nociception-selective blockade.

Gold nanoparticles stabilize peptide-drug-conjugates for sustained targeted drug delivery to cancer cells

BackgroundPeptide-drug-conjugates (PDCs) are being developed as an effective strategy to specifically deliver cytotoxic drugs to cancer cells. However one of the challenges to their successful application is the relatively low stability of peptides in the blood, liver and kidneys. Since AuNPs seem to have a longer plasma half-life than PDCs, one approach to overcoming this problem would be to conjugate the PDCs to gold nanoparticles (AuNPs), as these have demonstrated favorable physico-chemical and safety properties for drug delivery systems. We set out to test whether PEG coated-AuNPs could provide a suitable platform for the non-covalent loading of pre-formed PDCs and whether this modification would affect the bioavailability of the PDCs and their cytotoxicity toward target cancer cells.MethodsPeptides specifically internalized by A20 murine lymphoma cells were isolated from a phage library displaying 7mer linear peptides. Peptide specificity was validated by flow cytometry and confocal microscopy. PDCs were synthesized containing a selected peptide (P4) and either chlorambucil (Chlor), melphalan (Melph) or bendamustine (Bend). Gold nanoparticles were sequentially coated with citrate, PEG-6000 and then PDC (PDC-PEG-AuNP). The physico-chemical properties of the coated particles were analyzed by electrophoresis, TEM, UV–VIS and FTIR. Stability of free and PDC-coated AuNP was determined.ResultsBiopanning of the phage library resulted in discovery of several novel peptides that internalized into A20 cells. One of these (P4) was used to synthesize PDCs containing either Chlor, Melph or Bend. All three PDCs specifically killed A20 target cells, however they had short half-lives ranging from 10.6 to 15.4 min. When coated to PEG-AuNPs, the half-lives were extended to 21.0–22.3 h. The PDC-PEG-AuNPs retained cytotoxicity towards the target cells. Moreover, whereas pre-incubation for 24 h of free PDCs almost completely abolished their cytotoxic activity, the PDC-PEG-AuNPs were still active even after 72 h pre-incubation.ConclusionsPeptide-drug-conjugates hold potential for improving the target efficacy of chemotherapeutic drugs, however their short half-lives may limit their application. This hurdle can be overcome by easily conjugating them to gold nanoparticles. This conjugation also opens up the possibility of developing slow release formulations of targeted drug delivery systems containing PDCs.

Tailoring hydroxyapatite nanoparticles to increase their efficiency as phosphorus fertilisers in soils

Hydroxyapatite nanoparticles (HA-NPs) have been proposed as a novel phosphorus (P) fertiliser that could potentially provide increased efficiency through controlled release. In the present study, three types of HA-NPs were synthesised with differences in surface charge and hydrodynamic sizes before being incubated in two P-deficient soils (an Ultisol and a Vertisol) in the laboratory for up to 240 d. The three types of HA-NPs had surface charge values of +21 (±4.3), 0 (±3.5) and −12 (±2.7) mV in a neutral medium (pH 7). In the Ultisol (pH 4.7), the addition of HA-NPs resulted in a smaller initial increase in P availability than triple superphosphate (TSP) due to their lower solubility. However, P availability in the TSP treatment decreased over time due to adsorption of P to the soil constituents, with a concomitant increase in the NaOH-extractable P fraction. In contrast, the release of P from the HA-NPs remained relatively constant over the entire incubation period. After 45 d, the soils amended with negatively charged HA-NPs had higher levels of available P when estimated using diffusive gradients in thin films (DGT-P) compared to both the neutral and the positively charged HA-NPs. In the Vertisol (pH 8.2), although the addition of TSP increased P availability markedly, amendment with the three HA-NPs did not increase P availability due to the low solubility of hydroxyapatite at this high pH. Indeed, for the Vertisol, most of the P added as HA-NPs remained in the Ca-P fraction. Our results show that for the acidic Ultisol, HA-NPs with altered surface charges are potentially a useful form of slow release P.

Glutathione-PEGylated liposomal methylprednisolone in comparison to free methylprednisolone: slow release characteristics and prolonged lymphocyte depression in a first-in-human study.

Intravenous high-dose free methylprednisolone (MP) hemisuccinate is the primary treatment for an acute relapse in relapsing-remitting multiple sclerosis. However, it is inconvenient and its side effects are undesirable. Both dose and dosing frequency can be reduced by incorporating free MP in glutathione-PEGylated liposomes, creating a slow-release formulation with reduced toxicity and prolonged peripheral efficacy. This first-in-human study was designed to assess the safety, pharmacokinetics and pharmacodynamics of glutathione-PEGylated liposomes containing MP (2B3-201). The first part was a double-blind, three-way cross over study in 18 healthy male subjects, receiving ascending doses of 2B3-201, active comparator (free MP) or placebo. Part 2 of the study was an open-label infusion of 2B3-201 (different doses), exploring pretreatment with antihistamines and different infusion schedules in another 18 healthy male subjects, and a cross-over study in six healthy female subjects. MP plasma concentrations, lymphocyte counts, adrenocorticotropic hormone, osteocalcin and fasting glucose were determined. Safety and tolerability profiles were assessed based on adverse events, safety measurements and central nervous system tests. The most frequent recorded AE related to 2B3-201 was an infusion related reaction (89%). 2B3-201 was shown to have a plasma half-life between 24 and 37h and caused a prolonged decrease in the lymphocyte count, adrenocorticotropic hormone and osteocalcin, and a rise in fasting glucose. 2B3-201 is considered safe, with no clinically relevant changes in central nervous system safety parameters and no serious adverse events. In addition, 2B3-201 shows a long plasma half-life and prolonged immunosuppressive effects.

Thiocarbamate fungicides: reliable tools in resistance management and future outlook.

Among contact fungicides, dithiocarbamates have remained successful and are used worldwide. These organic sulfur fungicides, viz. mancozeb, maneb, zineb, ziram, thiram, metiram and propineb, have helped growers manage several economically important plant diseases. Their multi-site mode of action and broad-spectrum disease control make them some of the most common partners in mixtures of a number of single-site fungicides as part of resistance management strategies. Indeed, it was the part played by ethylene-bis-dithiocarbamates such as mancozeb in delaying the evolution of phenylamide resistance in several oomycete phytopathogens that laid the groundwork for mixture strategies to become a cornerstone of anti-resistance management in plant disease control. Dithiocarbamates, however, do not have systemic action, are only surface protectants and have to be applied prior to pathogen infection. Dithiocarbamates will likely continue play a key role as reliable resistance management tools to prolong the efficacy of single-site fungicides. The primary metabolite ethylene thiourea produced by some of these fungicides is considered a reproductive and endocrine disrupter in animals. Therefore, dithiocarbamates need to be used at reduced rates or in slow-release formulations. © 2017 Society of Chemical Industry.

Slow-Release Formulation of Cowpea Mosaic Virus for In Situ Vaccine Delivery to Treat Ovarian Cancer.

The plant viral nanoparticle cowpea mosaic virus (CPMV) is shown to be an effective immunotherapy for ovarian cancer when administered as in situ vaccine weekly, directly into the intraperitoneal (IP) space in mice with disseminated tumors. While the antitumor efficacy is promising, the required frequency of administration may pose challenges for clinical implementation. To overcome this, a slow release formulation is developed. CPMV and polyamidoamine generation 4 dendrimer form aggregates (CPMV‐G4) based on electrostatic interactions and as a function of salt concentration, allowing for tailoring of aggregate size and release of CPMV. The antitumor efficacy of a single administration of CPMV‐G4 is compared to weekly administration of soluble CPMV in a mouse model of peritoneal ovarian cancer and found to be as effective at reducing disease burden as more frequent administrations of soluble CPMV; a single injection of soluble CPMV, does not significantly slow cancer development. The ability of CPMV‐G4 to control tumor growth following a single injection is likely due to the continued presence of CPMV in the IP space leading to prolonged immune stimulation. This enhanced retention of CPMV and its antitumor efficacy demonstrates the potential for viral–dendrimer hybrids to be used for delayed release applications.

Chemical speciation and fate of tripolyphosphate after application to a calcareous soil

Adsorption and precipitation reactions often dictate the availability of phosphorus in soil environments. Tripolyphosphate (TPP) is considered a form of slow release P fertilizer in P limited soils, however, investigations of the chemical fate of TPP in soils are limited. It has been proposed that TPP rapidly hydrolyzes in the soil solution before adsorbing or precipitating with soil surfaces, but in model systems, TPP also adsorbs rapidly onto mineral surfaces. To study the adsorption behavior of TPP in calcareous soils, a short-term (48 h) TPP spike was performed under laboratory conditions. To determine the fate of TPP under field conditions, two different liquid TPP amendments were applied to a P limited subsurface field site via an in-ground injection system. Phosphorus speciation was assessed using X-ray absorption spectroscopy, total and labile extractable P, and X-ray diffraction. Adsorption of TPP to soil mineral surfaces was rapid (< 48 h) and persisted without fully hydrolyzing to ortho-P. Linear combination fitting of XAS data indicated that the distribution of adsorbed P was highest (~ 30–40%) throughout the site after the first TPP amendment application (high water volume and low TPP concentrations). In contrast, lower water volumes with more concentrated TPP resulted in lower relative fractions of adsorbed P (15–25%), but a significant increase in total P concentrations (~ 3000 mg P kg soil) and adsorbed P (60%) directly adjacent to the injection system. This demonstrates that TPP application increases the adsorbed P fraction of calcareous soils through rapid adsorption reactions with soil mineral surfaces.

Drug Compatibility and Distribution Assessments of a Bupivacaine-Polymer Formulation Measured Following Site-Directed Injection in Mice

Background: A long-acting local anaesthetic agent would enable superior post-operative analgesia. Our slow-release bupivacaine-polymer formulation comprising 15% bupivacaine loaded into a poly (DL-lactic acid co castor oil 3:7), DL-LA:CO was effective for up to 96 hours. In this study we determined in vivo drug levels of the formulation from plasma and tissue assay and we tested the feasibility of drug level assessments from an exudate sample collected in a novel device near the injection-site. Methods: Prior to formulation injection, a titanium cylinder dual-open-ended chamber was implanted in the dorso-lumber region of female ICR mice, to be used as a biological compartment. Following a healing period, the bupivacaine-polymer formulation was injected close to the sciatic nerve. Formulation assay samples were collected over one-week post-injection; exudate was drawn from the chamber in the anaesthetised animal; and blood and tissue samples from the sacrificed animal. Bupivacaine distribution in the exudate and plasma samples was determined by liquid chromatography–mass spectrometry developed for these experiments, and in tissue samples by high -performance liquid chromatography. Results: Bupivacaine was detected during the first 24h following formulation injection in all three samples (exudate, plasma and tissue), and decreased to almost undetectable levels by day 7 post-injection. Conclusion: Bupivacaine drug assay measured from an exudate sample may be applicable in addition or as a replacement for standard plasma and tissue assay in studies of drug pharmacokinetic distribution. The high sensitivity and simplicity of the metallic chamber implant to detect drug concentration and exudate analysis was confirmed in sever hepatic impairment.

EFFECT OF TRADITIONAL SOLUBLE AND SLOW RELEASE N-FERTILIZERS ON WHEAT &amp; THEIR RESIDUAL EFFECT ON SORGHUM AND BARLEY IN SOME SOILS OF EGYPT

A pot experiment was conducted under greenhouse conditions using pots (perforated at the bottom), with 12 kg soil capacity of each. Pots were seeded with wheat (Triticum aestivum Sakha 8), to study the effects of traditional soluble-N and slow release-N fertilizers. The soil of each pot was thoroughly mixed with P at a rate of 12 mg P/kg soil. Soil K was in sufficient amount. The experimental pots were contained 288 pots, which arranged in a complete randomized block design with three replicate in four factors of three forms of soil , four N-fertilizers ( two traditional soluble-N and the other two slow release-N fertilizers) , three rates of N-fertilizers as well as two rates of moisture regimes of 70 and 100 WHC . At wheat maturity after 24 weeks-growth, plants in each pot were cut 2-cm above soil surface, carefully washed, dried and weighted. After wheat harvested and in the same pots, in order to study the N-fertilizes residual effect, two successive crops of Sorghum vulgar c.v. Giza 15 and then barley Hordium, vulgar Giza 121 were planted and harvested after 9 and 16 weeks , respectively. The obtained results may be summarized as follows: The traditional soluble forms of N-fertilizers produced higher dry matter (gm./pot) of wheat crop compared with the slow release forms of N-fertilizers. Dry weights (gm/pot) of both sorghum and barley were more under fertilization with slow release forms of N-fertilizers, than under fertilization with the traditional soluble forms, with approximately equal to two fold and threefold, respectively. Slow release forms resulted in less N-uptake by wheat than the traditional soluble forms. While the slow release forms of N-fertilizers affected positively on N-uptake by both of sorghum and barley, with increases approximately equal to twice threefold more than the traditional soluble ones. ·Residues of slow release N- fertilizers have appropriate supply of sorghum and barley, at the two successive with amounts of (N), because their ability to continuous supply (N) for long periods of time.

A novel controlled release formulation of the Pin1 inhibitor ATRA to improve liver cancer therapy by simultaneously blocking multiple cancer pathways

Hepatocellular carcinoma (HCC) is the second leading cause of cancer deaths worldwide largely due to lack of effective targeted drugs to simultaneously block multiple cancer-driving pathways. The identification of all-trans retinoic acid (ATRA) as a potent Pin1 inhibitor provides a promising candidate for HCC targeted therapy because Pin1 is overexpressed in most HCC and activates numerous cancer-driving pathways. However, the efficacy of ATRA against solid tumors is limited due to its short half-life of 45min in humans. A slow-releasing ATRA formulation inhibits solid tumors such as HCC, but can be used only in animals. Here, we developed a one-step, cost-effective route to produce a novel biocompatible, biodegradable, and non-toxic controlled release formulation of ATRA for effective HCC therapy. We used supercritical carbon dioxide process to encapsulate ATRA in largely uniform poly L-lactic acid (PLLA) microparticles, with the efficiency of 91.4% and yield of 68.3%, and ~4-fold higher Cmax and AUC over the slow-releasing ATRA formulation. ATRA-PLLA microparticles had good biocompatibility, and significantly enhanced the inhibitory potency of ATRA on HCC cell growth, improving IC50 by over 3-fold. ATRA-PLLA microparticles exerted its efficacy likely through degrading Pin1 and inhibiting multiple Pin1-regulated cancer pathways and cell cycle progression. Indeed, Pin1 knock-down abolished ATRA inhibitory effects on HCC cells and ATRA-PLLA did not inhibit normal liver cells, as expected because ATRA selectively inhibits active Pin1 in cancer cells. Moreover ATRA-PLLA microparticles significantly enhanced the efficacy of ATRA against HCC tumor growth in mice through reducing Pin1, with a better potency than the slow-releasing ATRA formulation, consistent with its improved pharmacokinetic profiles. This study illustrates an effective platform to produce controlled release formulation of anti-cancer drugs, and ATRA-PLLA microparticles might be a promising targeted drug for HCC therapy as PLLA is biocompatible, biodegradable and nontoxic to humans.

Synthesis and characterization of emamectin-benzoate slow-release microspheres with different surfactants

Pesticide slow-release formulations provide a way to increase the efficiency of active components by reducing the amount of pesticide that needs to be applied. Slow-release formulations also increase the stability and prolong the control effect of photosensitive pesticides. Surfactants are an indispensable part of pesticide formulations, and the choice of surfactant can strongly affect formulation performance. In this study, emamectin-benzoate (EMB) slow-release microspheres were prepared by the microemulsion polymerization method. We explored the effect of different surfactants on the particle size and dispersity of EMB in slow-release microspheres. The results indicated that the samples had uniform spherical shapes with an average diameter of 320.5 ±5.24 nm and good dispersity in the optimal formulation with the polymeric stabilizer polyvinyl alcohol (PVA) and composite non-ionic surfactant polyoxyethylene castor oil (EL-40). The optimal EMB pesticide slow-release microspheres had excellent anti-photolysis performance, stability, controlled release properties, and good leaf distribution. These results demonstrated that EMB slow-release microspheres are an attractive candidate for improving pesticide efficacy and prolonging the control effect of EMB in the environment.

Herbicidal activity of slow-release herbicide formulations in wheat stands infested by weeds

ABSTRACTThe present study reports the herbicidal activity of metribuzin and tribenuron-methyl embedded in the degradable matrix of natural poly-3-hydroxybutyrate [P(3HB)/MET and P(3HB)/TBM]. The developed formulations were constructed as films and microgranules, which were tested against the weeds such as white sweet clover Melilotus albus and lamb's quarters Chenopodium album in the presence of soft spring wheat (Triticum aestivum, cv. Altaiskaya 70) as the subject crop for investigation. The activity was measured in laboratory scale experiments by determining the density and weight of the vegetative organs of weeds. The study was also aimed at testing the effect of the experimental formulation on the growth of wheat crop as dependent on the method of herbicide delivery. The experimental MET and TBM formulations showed pronounced herbicidal activity against the weed species used in the study. The effectiveness of the experimental formulations in inhibiting weed growth was comparable to and, sometimes, higher than that of the commercial formulations (positive control). The amount of the biomass of the wheat treated with the experimental herbicide formulations was significantly greater than that of the wheat treated with commercial formulations.

Slow-release praziquantel for dogs: presentation of a new formulation for echinococcosis control

BackgroundEchinococcosis is a serious, zoonotic, parasitic disease with worldwide distribution. According to a epidemiological survey in 2012 in China, there are 20,000 infected patients and more than 50 million people at the risk. As the dog is the main, definitive host, the Government of China encourages monthly praziquantel treatment of every dog. However, this is difficult to achieve in geographically challenging areas, such as the Tibetan plateau, where there are also many dogs without owners. To overcome these problems, we investigated the transmission blocking capacity of a slow-release formulation of praziquantel administered by subcutaneous injection.MethodsThe impact of a slow-release preparation of two pharmacokinetically stereoselective praziquantel enantiomers, i.e., R-(−)-praziquantel (R-PZQ) and S-(+)-praziquantel (S-PZQ) absorbed into a biodegradable polymer was studied in beagle dogs (N = 6). The preparation was given by subcutaneous injection using a single dose of 100 mg/kg. Chiral-selective, high-performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS) were applied to measure the praziquantel enantiomers in the plasma of the dogs. The lower limit for estimating plasma concentrations accurately for R-PZQ was 4 ng/ml and for S-PZQ 20 ng/ml. The pharmacokinetic parameters were calculated by a noncompartmental analysis model using Drug Analyze System (DAS) software 2.0. The SPSS 19.0 software was used for statistical analysis, and the statistical comparison between enantiomers was assessed using the two-tailed t-test.ResultsTwo hours after administration, peak concentrations of R-PZQ and S-PZQ: 321 ± 26 and 719 ± 263 ng/ml, respectively, were achieved. After 180 days, the average plasma concentration of R-PZQ in the six dogs had decreased to 13 ng/ml. The average concentration value of S-PZQ was higher than that of R-PZQ in the first 90-day period but fell afterwards and could not be accurately estimated when dropping below 20 ng/ml (the lower methodological limit for this enantiomer). Taking all the dogs into account, the average maximum concentration (Cmax) of S-PZQ in plasma over the first 3 months was higher than that of R-PZQ by 114.0% (P < 0.05), while the average mean retention time (MRT) of R-PZQ in plasma was higher than that of S-PZQ by 96.3% (P < 0.05).ConclusionsPraziquantel given as an in situ slow-release formulation by subcutaneous injection resulted in concentrations of the active principle in beagle dogs, which should be capable of resisting new Echinococcus infections for at least 6 months. The new formulation of praziquantel represents a potential, alternative way of presenting medication against tapeworm infections in dogs.

Selenomethionine as a Safer Substitute for Barium Selenate in Long-Acting Injectable Se Supplements for Food-Producing Animals.

Nutritional supplementation with selenium (Se) can prevent Se deficiency in food-producing animals. Injection with slow-release formulations is a preferred method for free-range grazing sheep and cattle, and barium selenate (BaSeO4) provides optimal efficacy. This chemical can become a health risk to humans if the concentrated depot of an injection site is consumed, and consequently such use is recently banned in the EU. A possible replacement is selenomethionine (SeMet), a naturally occurring form of Se supplementation hitherto only administered orally. In four animal studies we found that injection with SeMet maintained nutritionally adequate concentrations of Se in blood and tissues of lambs for at least 191 days and in blood and milk of dairy cows for at least 95 days. Stereoisomer forms L- and DL-SeMet were functionally equivalent. This is the first demonstration that injectable SeMet can deliver efficacy similar to BaSeO4 but with less risk of undesirable residues in edible tissues.

Mechanochemical Encapsulation of an Aromatic Hydrocarbon into Mesoporous Silica as a Simple Slow Release Formulation

AbstractThe incorporation of para‐dichlorobenzene into mesoporous silica (with the pore diameter of 1.9 ‐ 3.1 nm) was conducted by a mechanochemical reaction, where mesoporous silica powder and para‐dichlorobenzene powder were mixed together using a mortar and a pestle at room temperature. The resulting host‐guest complexes exhibited useful controlled release of para‐dichlorobenzene into air as evaluated by the change in the sample weight. The release speed was affected by the pore size of the used mesoporous silicas; the release of para‐dichlorobenzene was suppressed when the mesoporous silica with the pore size of 3.1 nm was used. The present method for the slow release formulation has such advantages as the materials variation (porous silicas with different pore size and possible pore surface modification) and simple solvent free operation for the sample preparation (mechanochemical encapsulation into the pore).