Controlled-release Preparation Research Articles

Temperature-responsive microcapsule hydrogel fabricated by pickering emulsion polymerization for pheromones application

Insect pheromone is a natural effective biological pesticide. To improve the utilization efficiency of pheromone pesticides and reduce labor costs, a sustained and controlled release preparation coordinating with the circadian rhythm of insects has been proposed by our previous report. However, that preparation has some deficiencies, such as the loading capacity of pheromone and sustained time. In order to overcome the existent shortcomings, a temperature-responsive release microcapsule hydrogel loaded with myrcene (as a pheromone model) was fabricated by Pickering emulsion polymerization using modified SiO2 nanoparticles as a stabilizer of microcapsule wall, octadecane and Poly(N-isopropylacrylamide) (PNIPAM) separately as temperature responders of microcapsule core and wall in the present study. The morphological structure and thermal performance of the microcapsule hydrogel were characterized. The release behaviors of myrcene at different environmental temperatures and alternating temperature cycles were also tested. The results indicated that myrcene was successfully loaded in the Myrcene/Octadecane@SiO2-PNIPAM (MOSP) microcapsule hydrogel with encapsulation efficiency and loading capacity of 80.3 % and 13.3 %, respectively. The results of the myrcene release under simulated diurnal temperature cycles revealed that the cumulative release amount was only about 43 % during 15 cycles and release rates respectively were about 0.79 μg/h at 35 °C and 0.058 μg/h at 25 °C, which demonstrated the persistent temperature sensitivity and good temperature rhythm remained after 15 cycles. These results suggested that the MOSP microcapsule hydrogel had a good controlled release effect on myrcene and could adapt well to the circadian rhythm activity of some insects. Therefore, this study provided a promising strategy to improve the utilization efficiency of pheromones through the combination of octadecane and PNIPAM as pheromones release controllers.

Study of Gelatin-grafted-2-Acrylamido-2-methylpropane sulfonic acid hydrogels as a controlled release vehicle for amorphous solid dispersion of Tripterygium Wilfordii bioactive constituents

The development of controlled-release preparations for herbal medicines remains challenging due to their complex compositions and distinct physicochemical properties. Tripterygium Wilfordii (TWHF) is a traditional Chinese medicine used to treat inflammatory diseases like rheumatoid arthritis, neurodegenerative and autoimmune diseases. The main active ingredients include diterpenes, triterpenes and alkaloids. These agents have poor pharmacokinetic and physicochemical characteristics, making it difficult to achieve therapeutic benefits. In the present study, a solid dispersion of TWHF (TWHF-SD) was prepared and loaded into Gelatin-grafted-2-Acrylamido-2-methylpropane sulfonic acid hydrogels (Gelatin-g-AMPS) for controlled drug release. A total of 48 compounds were identified in TWHF-SD using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) analysis. The hydrogel's structure and physicochemical properties were confirmed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis(TGA), and Differential Scanning Calorimetry (DSC). Studies regarding hydrogel structure–function relationships were conducted, such as average weight between two or mor crosslinks (Mc), polymer volume fraction (V2,s), and diffusion coefficient (D). Hydrogel swelling and drug release from loaded hydrogels were slightly higher at pH 1.2 (swelling ratio of 60.84%, drug release of 85.08) than at pH 7.4 (swelling ratio of 46.46%, drug release of 75.03%) after 48 h. The gel fraction of hydrogel increased with increasing polymer/crosslinker ratios. Additionally, in vitro studies confirmed that the developed hydrogels were effective against bacterial growth and had good antioxidant properties.

Constructing a drug release model by central composite design to investigate the interaction between drugs and temperature-sensitive controlled release nanoparticles

To study the release behavior of a thermosensitive controlled release drug delivery system and construct a predictable mathematical model of drug release, poly(N-isopropylacrylamide-co-Allylamine) (P(NIPA-AL17)) and ploy(styrene sulfonate) (PSS) were functionalized on the surface of hollow mesoporous carbon nanoparticles (HMCNs) through layer-by-layer (LBL) assembly to construct a photothermal responsive controlled release system. A five-level four-factorial central composite design (CCD) was performed to investigate the relationship between four independent variables including drug loading (A), number of polymer layers (B), temperature (C) and vibration rate of the shaker (D), and three dependent response variables, including cumulative release over 1 h (Y1), cumulative release over 24 h (Y2) and the release rate constant k (Y3). The CCD results indicate that A and C significantly affect Y1 (P < 0.05). C significantly affects Y2 (P < 0.05). A and B is found to affect Y3 (P < 0.05) significantly. When C is below 39 °C, Y1 and Y2 decrease with the increase of A and B, and when C is above 39 °C, they increase with the increase of A and B; Y3 decreases as A and B increase; and D shows the least or even no influence on Y1, Y2 and Y3. The constructed predictable mathematical model will provide a scientific reference for the further development and application of photothermal responsive controlled-release preparations.

Effervescent Tablets: Everything You Need To Know

Oral dosage forms are the most popular way of taking medication, despite having some disadvantages compared with other methods like risk of slow absorption of the medicament, which can be overcome by administering the drug in liquid form, therefore, possibly allowing the use of a lower dosage. However, instability of many drugs in liquid dosage form limits its use. Effervescent technique can be used as alternate to develop a dosage form which can accelerate drug disintegration and dissolution, is usually applied in quick release preparations. Along with the development of new pharmaceutical technique, effervescent tablets are more and more extensively to adjust the behavior of drug release, such as in sustained and controlled release preparations, pulsatile drug delivery systems, and so on. In this review we have discussed about formulation, evaluation, advantages of effervescent tablets and also demonstrated the new applying of effervescent technique in effervescent tablets. Keywords: Effervescent tablets. Carbon tablet, Effervescent granules.

Formulation, Characterization, and Antibacterial Study of Microsponge- Loaded Gel of Clarithromycin for Topical Drug Delivery

Background: Microsponge drug delivery systems comprise spherical and porous micro-spheres for prolonged topical drug delivery. These systems considerably reduce the undesirable side effects, offering improved patient compliance and reduced dosing frequency. Objective: The present study focused on developing topical controlled release preparations of microsponges-loaded gel of clarithromycin to cure bacterial skin infections. Materials and Methods: Four batches of microsponges (F1, F2, F3, and F4) of clarithromycin (CLR) containing fixed amounts of clarithromycin (100 mg), dichloromethane (5 ml), polyvinyl al-cohol (5 % w/v) and distilled water (25 ml) with varying polymer concentrations were prepared by the quasi-emulsion solvent diffusion method and evaluated for % Production Yield, % drug content, % encapsulation efficiency, particle size, polydispersity index (PDI) and % drug release characteris-tics. The selected microsponge formulation (F3) was incorporated in Carpopol 934 gel for topical application. The prepared gel (CLRMS-F3 Gel) was evaluated for physical characteristics, pH, spreadability, viscosity, and in vitro drug release. Furthermore, the gel formulation was compared with pure clarithromycin gel for antibacterial activity against the gram-positive (S. aureus) and gram-negative strain (E. coli.) using the cup and plate method. Results and Discussion: The F3 microsponge formulation exhibited a production yield of 83.75%, drug content (21.5 ± 0.50 %), and encapsulation efficiency of 86.04 ± 2.30%. Their particle size was satisfactory (3.80 ± 0.01 μm), and they were found to be spherical and porous in nature. F3 microsponges released 69.36 ± 1.27% of the drug over a period of 8 hrs and were incorporated into the gel formulations. The gel prepared using F3 microsponges was transparent, homogenous, and exhibited a pH of 6.8 ± 0.02, spreadability of 9.92 ± 0.44 g/cm, and viscosity of 35370.17 ± 493.09 centipoises. The CLRMS-F3 gel released 82.13 ± 0.47% drug in 12 hrs using a zero-order kinetic. The antibacterial activity studies revealed a higher potency against both S. aureus and E. coli of the prepared CLRMS-F3 gel compared to pure CLR gel and azithromycin standard. Conclusion: Based on the above study, it may be concluded that microsponges’ gel formulation can be potentially useful in improving topical drug delivery of antibacterial agents and can give better therapeutic efficacy.

Bibliometric analysis of articles on nanoemulsion and/or in-situ gel for ocular drug delivery system published during the 2011–2021 period

The bibliometric data were extracted from the Scopus database to investigate the conceptual framework of ocular nanoemulsion and/or in-situ gel drug delivery system using “ocular” AND “nanoemulsion” OR “in-situ gel” keywords. The data were evaluated with RStudio and VOSviewer program. The results reveal that the publication trends tend to increase continually. India is the most impactful country, and the most constructive institution is Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University. International Journal of Pharmaceutics is the top influential source. Ali A is the most prolific author. The title of the most impactful article was In-situ gelling systems based on Pluronic F127/Pluronic F68 formulations for ocular drug delivery”. “Controlled release” is the most popular keyword. These results provide insights for stimulating research collaborations and revealing open issues of controlled-release ocular preparation to overcome an ocular barrier and enhance patient compliance.

Preparation and Characterization of Controlled-Release Floating Bilayer Tablets of Esomeprazole and Clarithromycin.

Controlled-release effervescent floating bilayer tablets reduce dosage frequency and improve patient compliance with enhanced therapeutic outcomes. Generally, two different tablets of clarithromycin and esomeprazole, respectively, are given for the treatment of Helicobacter pylori infection and it might be worth incorporating both in a single tablet. In the current study, controlled-release floating bilayer tablets of clarithromycin and esomeprazole (F1–F4) were developed with different rates of polymeric materials by a direct compression method. During the formulation, Fourier-transform infrared spectroscopy (FTIR) analysis was performed for possible interactions between drugs and excipients. No interactions between drugs and excipients were noted. Moreover, the bilayer tablets’ thickness, diameter, friability, hardness, weight variation, dissolution, and percent purity were found within the acceptable limits. The floating lag time and total floating time of all formulations were found to be < 25 s and 24 h, respectively. The release of both the clarithromycin and esomeprazole started at the same time from the controlled-release floating bilayer tablets by anomalous non-Fickian diffusion, and the polymeric materials extended the drug release rate up to 24 h. In the case of F1, the results approached ideal zero-order kinetics. The dissolution profiles of the tested and reference tablet formulations were compared, but no significant differences were observed. It can be concluded that such controlled-release effervescent floating bilayer tablets can be efficiently used in clinical practice to reduce dosage frequency and increase patient compliance with continuous drug release for 24 h, which ultimately might enhance therapeutic efficacy.

Mechanochemical Effect on Controlled Drug Release of Konjac Glucomannan Matrix Tablets during Dry Grinding

To design a controlled drug release preparation based on a safe natural material, a Konjac glucomannan (KGM) mixture containing 16.0 w/w% calcium hydroxide (Ca(OH)2) was ground in a planetary ball mill for 0–120 min. The mechanochemical effect on the physicochemical properties of the KGM ground product was investigated by Fourier-transform infrared spectroscopy (FT-IR), powder X-ray spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and drug release testing. The FT-IR spectra of the ground KGM indicated that the deacetylation reaction of KGM was accelerated in the Ca(OH)2-containing sols by mechanochemical energy, and the degree of deacetylation of KGM was dependent on the grinding time. The time required for tablet disintegration of the KGM matrix tablets containing theophylline increased as the grinding time increased; therefore, drug release was sustained. The Higuchi plots of the matrix tablets obtained from KGM ground for 60–120 min exhibited good linearity because they maintained their gel matrix tablet shape during the release test. However, KGM tablets ground for 0–30 min exhibited nonlinear curves, which were caused by tablet disintegration. This suggests that drug release from the KGM matrix tablet can be freely controlled by the degree of mechanochemical treatment.

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.

Study on preparation and in vitro anti-tumor activity of chitosan-modified mesoporous silica hybrids by GPTMS cross-linking agent

Using (3–glycidoxypropyl) trimethoxysilane (GPTMS) as the cross-linking agent, a novel pH-responsive nanocarrier based on chitosan/mesoporous silica hybrids (MSNs/CS) was successfully fabricated. The optimal technological conditions for the synthesis of MSNs or MSNs/CS were investigated, and the composites were characterized using field emission electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectra, X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and nitrogen adsorption/desorption isotherms, among other techniques. Haemolysis and MTT assays showed that MSNs and MSNs/CS had good biocompatibility, when the concentration of MSNs/CS was as high as 2 mg/mL, the hemolysis rate was still lower than 5%, and the cell viability of the carrier material was still greater than 80% when the concentration of MSNs/CS reached 250 μg/mL. Doxorubicin hydrochloride (DOX•HCl), as the model therapeutic agent, was released faster in simulated tumor microenvironment, and the drug loading and encapsulation efficiency of MSNs/CS were 32.47 ± 0.478% and 96.164 ± 0.0643%, respectively. Moreover, the in vitro drug release curve of MSNs/CS is highly fitted to the Higuchi equation, which indicates that the MSNs/CS-DOX•HCl system has pH response and sustained-release characteristics. Intracellular drug uptake and release experiments as well as the in-vitro anti-tumor efficacy, both demonstrated that loading DOX•HCl on the MSNs/CS improved the drug's tumor-targeted therapeutic effect. MSNs/CS synthesized by GPTMS was shown to be a novel idea for the research and development of targeted sustained and controlled-release preparations.

Formulation and Evaluation of Paracetamol Effervescent Tablet

Oral dosage forms are the most popular way of taking medication, despite having some disadvantages compared with other methods like risk of slow absorption of the medicament, which can be overcome by administering the drug in liquid form, therefore, possibly allowing the use of a lower dosage. However, instability of many drugs in liquid dosage form limits its use. Effervescent technique can be used as alternate to develop a dosage form which can accelerate drug disintegration and dissolution, is usually applied in quick release preparations. The tablet is added into a glass of water just before administration and the drug solution or dispersion is to be drunk immediately. The tablet is quickly broken apart by internal liberation of CO2 in water due to interaction between tartaric acid and citric acid with alkali metal carbonates or bicarbonates in presence of water. Due to liberation in CO2 gas, the dissolution of API in water as well as taste masking effect is enhanced Along with the development of new pharmaceutical technique, effervescent tablet are more and more extensively to adjust the behavior of drug release, such as in sustained and controlled release preparations, pulsatile drug delivery systems, and so on. In present work an attempt has been made to formulate an effervescent tablet containing immediate release of paracetamol using various acids and bases. In present work we are used different acids and bases in different concentration. The formulation of tablets was done by using wet granulation as well as dry granulation in that technique wet granulation which was found acceptable. Then formulated tablets were evaluated for hardness, friability, weight variation, and disintegration time . From study it was concluded that F5 shows the better result than the F1, F2, and F3 &amp; F4.&#x0D;

Study on pharmacokinetics of nimodipine nano-controlled release agent modified by host-guest reaction of β-cyclodextrin in rats

Nimodipine (NIMO) has been identified as a second-generation dihydropyridine calcium channel antagonist. NIMO’s specificity for the cerebrovascular smooth muscle contributes to its broad usage in treating ischemic cerebrovascular diseases in the elderly. Therefore, enhancing NIMO’s therapeutic effect and reducing its adverse reactions caused by short-term repeated use have become a focus of research. As a result, a new controlled-release preparation of NIMO, the carboxymethyl chitosan/nimodipine-hydroxypropyl-β-cyclodextrin nanoparticle (Nano-NIMO), was constructed based on hydroxypropyl-β-cyclodextrin. The novel composite Nano-NIMO preparation could significantly improve the stability of NIMO in rat plasma, achieving an absolute bioavailability as high as 62.3%, which is three times that of the traditional NIMO oral preparation. Therefore, Nano-NIMO is expected to provide a new direction for the preparation of modified controlled-release Nano- NIMO agents.

Starch/Poly(glycerol-adipate) Nanocomposites: A Novel Oral Drug Delivery Device

Biocompatible and bio-based materials are an appealing resource for the pharmaceutical industry. Poly(glycerol-adipate) (PGA) is a biocompatible and biodegradable polymer that can be used to produce self-assembled nanoparticles (NPs) able to encapsulate active ingredients, with encouraging perspectives for drug delivery purposes. Starch is a versatile, inexpensive, and abundant polysaccharide that can be effectively applied as a bio-scaffold for other molecules in order to enrich it with new appealing properties. In this work, the combination of PGA NPs and starch films proved to be a suitable biopolymeric matrix carrier for the controlled release preparation of hydrophobic drugs. Dynamic Light Scattering (DLS) was used to determine the size of drug-loaded PGA NPs, while the improvement of the apparent drug water solubility was assessed by UV-vis spectroscopy. In vitro biological assays were performed against cancer cell lines and bacteria strains to confirm that drug-loaded PGA NPs maintained the effective activity of the therapeutic agents. Dye-conjugated PGA was then exploited to track the NP release profile during the starch/PGA nanocomposite film digestion, which was assessed using digestion models mimicking physiological conditions. The collected data provide a clear indication of the suitability of our biodegradable carrier system for oral drug delivery.

Design and development of sustained and controlled release preparations in traditional Chinese medicine based on quality by design( QbD)

In this paper,the design and development of sustained and controlled release preparations in traditional Chinese medicine( TCM) based on quality by design( QbD) was put forward,aiming at the current situation that the final product quality is affected by multiple factors during the development of sustained and controlled release preparations in TCM. The important development of sustained and controlled release preparations in western medicine in recent years was summarized. According to the complex process of TCM,the concept of QbD was proposed to design and develop sustained and controlled release preparations in TCM. QbD concept was used to analyze the complex factors affecting sustained and controlled release preparations in TCM,and determine the high risk factors affecting the quality of the final product. The high risk factors were controlled from the process to achieve the goal of quality control.This article could provide research ideas for the sustained and controlled release preparations with complex components in TCM,so as to promote the research and development of sustained and controlled release preparations in TCM.

Phospholipid-modified poly(lactide-co-glycolide) microparticles for tuning the interaction with alveolar macrophages: In vitro and in vivo assessment

Controlled drug delivery to the lungs is promising with plentiful advantages over current rapid release products. However, alveolar macrophage clearance has severely hindered the application of inhaled controlled release preparations. The objective of our study was to explore the feasibility to decorate poly(lactide-co-glycolide) (PLGA) microparticles with endogenous phospholipids found in the deep lungs, thus, to regulate the interplay with alveolar macrophages. The influence of the phospholipid amount and type on macrophage uptake of PLGA microparticles was investigated systemically under both in vitro (RAW264.7 and NR8383) and in vivo conditions. The uptake rate (k) by macrophages, in vivo elimination rate from the bronchoalveolar lavage fluid (k′) and elimination rate from the whole lung (k″) were used as parameters for evaluation. Our data showed that a modification with dipalmitoyl phosphatidylcholine (DPPC) enhanced the macrophage phagocytosis significantly over the unmodified counterparts. Thereafter, using the same modification ratio, remarkable enhancement of macrophage uptake was found in the presence of different types of other phospholipids, especially with distearoyl phosphatidylethanolamine (DSPE). When replaced by a poly(ethylene glycol)-conjugated version of DSPE the uptake of the modified PLGA microparticles was reduced by ~200%. Meanwhile, the drug content in the lung tissue was improved by 3-fold (area under the curve value). Finally, it was possible to establish a correlation between in vitro phagocytosis and in vivo lung elimination rate for the investigated formulations. Overall, our study demonstrated that phospholipids play an important role in modulating the clearance of microparticle-based drug delivery vehicles, which gives a meaningful insight into the development of prolonged drug release system for inhalation.

1023. A Controlled-Release Prescription Oral Opioid Can Prolong S. aureus Survival in Injection Drug Preparation Equipment and Potentially Increase Bacteremia Risk

Background S. aureus is the most common pathogen associated with injection drug use-associated endocarditis (IDUaIE). Our center has a high incidence of IDUaIE and the opiate of choice in our population is hydromorphone-controlled release (HCR), a prescribed oral opiate widely used in Canada and Europe. The complex technique for preparation for injection provides multiple opportunities for contamination of the solution and the controlled-release preparation contains several excipients (carbohydrates, protein, and iron), which could enhance Staphylococcal survival. A large amount of drug remains in the injection drug preparation equipment (IDPE) after each use and therefore, used IDPE is saved by people who inject drugs (PWID) for subsequent reuse by adding more water and then injecting the solution intravenously.MethodsUsed IDPE was collected from active PWID, rinsed with sterile water, aspirated into a syringe in a technique which mimicked reuse of equipment by PWID, and then plated on Mannitol salt agar (MSA). Bacterial isolates from local bacteremic PWID were used to test the survival of S. aureus (MRSA and MSSA) and S. pyogenes on unused IDPE with HCR or hydromorphone immediate release (HIR). The solutions were aspirated using techniques similar to that of local PWID and then plated on MSA and Blood agar.ResultsA total of 109 used IDPE samples were collected between March 2017 and March 2018. S. aureus was detected in 15/94 (16%) IDPE samples that had been used for injection of HMC (seven MRSA, seven MSSA, and two borderline resistant [one sample contained both MRSA and MSSA]), but 0/15 (0%) samples used for hydromorphone immediate release (HIR). HCR, but not HM, was associated with greater survival of MSSA and MRSA (but not S. pyogenes) in solutions of the drug when compared with sterile water vehicle control (Figure 1). There was a 2-log reduction in the number of viable S. aureus when IDPE containing HCR solutions spiked with MRSA or MSSA were heated with a cigarette lighter until bubbling (<10 seconds).ConclusionIDPE that has been used in the preparation of HCR is frequently contaminated with S. aureus; and in vitro HCR, but not HM, prolongs the survival of MRSA and MSSA. Heating IDPE may be an effective harm-reduction strategy to reduce bacterial complications of injection of HCR. Disclosures All authors: No reported disclosures.

Formulation and evaluation of effervescent tablets: a review

Oral dosage forms are the most popular way of taking medication, despite having some disadvantages compared with other methods like risk of slow absorption of the medicament, which can be overcome by administering the drug in liquid form, therefore, possibly allowing the use of a lower dosage. However, instability of many drugs in liquid dosage form limits its use. Effervescent technique can be used as alternate to develop a dosage form which can accelerate drug disintegration and dissolution, is usually applied in quick release preparations. Along with the development of new pharmaceutical technique, effervescent tablet are more and more extensively to adjust the behaviour of drug release, such as in sustained and controlled release preparations, pulsatile drug delivery systems, and so on. This review demonstrated the new applying of effervescent technique in effervescent tablets.&#x0D; Keywords: Effervescent Tablet, Sustained release, Floating Delivery System

Long-term safety, tolerability, and efficacy of OROS® hydromorphone in patients with chronic pain

To assess the safety and efficacy of long-term repeated dosing of OROS hydromorphone in chronic pain patients. This multicenter, open-label extension trial enrolled patients from three short-term OROS hydromorphone trials. Fifty-six centers in the United States and Canada. Adults with chronic cancer pain or chronic nonmalignant pain who were receiving stable doses of OROS hydromorphone (> or = 8 mg/day). Three hundred and eighty-eight patients were enrolled, 106 patients completed at least 12 months of therapy. OROS hydromorphone (individualized doses) was administered once daily. Safety and efficacy (Brief Pain Inventory and patient and investigator global evaluations) were assessed at monthly visits. The median duration of extended OROS hydromorphone therapy was 274 days. The median daily dose of study medication was 32.0 mg at extension-study baseline, 40.0 mg at month 3, and 48.0 mg at months 6, 9, and 12, respectively. The most frequently reported adverse events were nausea (n = 93, 24.0 percent) and constipation (n = 75, 19.3 percent). The analgesic effects of OROS hydromorphone, assessed using the Brief Pain Inventory, were maintained throughout the extension. At 12 months, 72.4 percent of patients and 75.9 percent of investigators rated overall treatment as good, very good, or excellent. Once-daily OROS hydromorphone is an osmotically driven, controlled-release preparation that may be particularly well suited to long-term use, because it provides consistent plasma concentrations and sustained around-the-clock analgesia. In this study, the benefits of OROS hydromorphone attained in short-term studies were maintained in the long-term when daily administration was continued.

Starch Phosphate Microgels for Controlled Release of Biomacromolecules

Gel-forming starch phosphates with a content of acidic phosphate groups ranging from 2.1 to 3.8 mmol/g were obtained in a phosphoric acid-urea system. The rates of starch phosphate degradation in buffer solution in the absence of amylase and in the presence of this enzyme were investigated in vitro. Starch phosphate gels were shown to be prone to enzymatic degradation. However, the rate of biodegradation decreased gradually as the content of phosphate groups increased. The use of microgels with average particle sizes in the range of 7.8–60.1 μm for the production of controlled-release preparations of interferon-alpha 2b has been demonstrated to be possible in principle.

Preparation and Characterization of Controlled-Release Avermectin/Castor Oil-Based Polyurethane Nanoemulsions

Avermectin (AVM) is a low-toxic and high-active biopesticide, but it can be easily degraded by UV light. In this paper, biodegradable castor oil-based polyurethanes (CO-PU) are synthesized and used as carriers to fabricate a new kind of AVM/CO-PU nanoemulsion through an emulsion solvent evaporation method, and the chemical structure, colloidal property, AVM loading capacity, controlled-release behavior, foliar adhesion, and photostability of the AVM/CO-PU drug delivery systems are investigated. Results show that AVM is physically encapsulated in the CO-PU carrier nanospheres, the diameter of the AVM/CO-PU nanoparticles is <50 nm, and the AVM/CO-PU films are flat and smooth without any AVM aggregate. The drug loading capacity is up to 42.3 wt % with a high encapsulation efficiency of >85%. The release profiles indicate that the release rate is relatively high at the early stage and then slows, which can be adjusted by loaded AVM content, temperature, and pH of the release medium. The foliar pesticide retention of the AVM/CO-PU nanoemulsions is improved, and the photolysis rate of AVM in the AVM/CO-PU nanoparticles is significantly slower than that of the free AVM. A release mechanism of the AVM/CO-PU nanoemulsions is proposed, which is controlled by both diffusion and matrix erosion.