Formulation of amphotericin B as nanosuspension for oral administration

Amphotherin B was formulated in a nanosuspension as a new oral drug delivery system for the treatment of experimental visceral leishmaniasis. Amphotericin B (AmB) nanosuspensions were produced by high pressure homogenisation obtaining particles with a PCS diameter of 528 nm. Environmental stability was determined in artificial gastrointestinal fluids at different pH and electrolyte concentrations. In vivo efficacy was determined in a mouse model of visceral leishmaniasis. Following oral administration (5 mg kg(-1)), micronised amphotericin B did not show any curative effect. However, administrations of amphotericin B nanosuspension, reduced liver parasite load by 28.6% compared to untreated controls.     

Enhanced nimodipine bioavailability after oral administration of nimodipine with morin, a flavonoid, in rabbits

The aim of this study was to investigate the effect of morin on the bioavailability of nimodipine after administering nimodipine (15 mg/kg) orally to rabbits either co-administered or pretreated with morin (2, 10 and 20 mg/kg). The plasma concentrations of nimodipine in the rabbits pretreated with morin were increased significantly (p < 0.05 at 10 mg/kg, p < 0.01 at 20 mg/kg) compared with the control, but the plasma concentrations of nimodipine co-administered with morin were not significant. The areas under the plasma concentration-time curve (AUC) and the peak concentrations (Cmax) of the nimodipine in the rabbits pretreated with morin were significantly higher (p < 0.05 at 10 mg/kg, p < 0.01 at 20 mg/kg), but only the Cmax of nimodipine coadministered with morin 10 mg/kg was increased significantly (p < 0.05). The absolute bioavailability (A.B%) of nimodipine in the rabbits pretreated with morin was significantly (p < 0.05 at 10 mg/kg, p < 0.01 at 20 mg/kg) higher (54.1-65.0%) than the control (36.7%). The increased bioavailability of nimodipine in the rabbits pretreated with morin might have been resulted from the morin, which inhibits the effiux pump P-glycoprotein and the first-pass metabolizing enzyme by cytochrome P-450 3A4 (CYP 3A4).     

尼莫地平缓释片制备

目的尼莫地平缓释片制备。方法通过比较体外释放度筛选处方。将尼莫地平微粉化与羟丙甲纤维素等混合,湿法制粒后制备缓释片,测定其释药度。结果羟丙甲纤维素、乳糖等对释放度均有影响。结论试制的与已经上市的尼莫地平缓释片释放行为基本一致。     

国产尼莫地平片剂的人体生物利用度

目的:比较两家药厂生产的尼莫地平(Nim)片的生物利用度.方法:9名健康志愿者随机4、5交叉单剂量po Nim 120mg后,HPLC法测定血清药物浓度,采用非房室模型分析得到有关的生物利用度参数.结果:A和B片的C_(max)分别为(50.27±28.23),(123.60±37.96)ng/ml;t_(max)分别为(0.43±0.24),(0.63±0.29)h;AUC分别为(102.34±42.06),(245.87±54.10)ng·h/ml ,结论:A片相对于B片的生物利用度为41.62%,B片的po吸收和生物利用度显著优于A.     

Formulation of lipid-based delivery systems for oral administration: materials, methods and strategies

Oral lipid-based drug delivery systems may include a broad range of oils, surfactants, and cosolvents. This diversity makes comparison of lipid-based formulations difficult. Although the relationship between formulation and drug absorption is understood at a conceptual level, performance in vivo cannot be predicted with confidence at present. The Lipid Formulation Classification System (LFCS) identifies the factors which are likely to affect performance in vivo. There is now a need to establish performance criteria which will facilitate in vitro-in vivo correlation studies. In this review we discuss the properties of excipients, and identify criteria for selection of excipients for lipid-based formulations. Excipients are discussed in the context of the LFCS, our existing knowledge of the fate of these materials during dispersion and digestion, and the likely consequences of their use in formulations. We outline the formulation strategies that can be used for each type of lipid formulation, and suggest a framework for the in vitro testing of each type. Finally we address the choice of lipid formulations in relation to the physicochemical properties of the drug.     

Formulation and bioequivalence of two valsartan tablets after a single oral administration

The aim of this study is to assess the quality of Valzan^® tablet (160 mg, valsartan immediate release test formulation) by comparing its pharmacokinetic parameters with Diovan^® tablet (160 mg, valsartan reference formulation). Valzan^® tablets were prepared according to a dry granulation method (roll compaction). To assess the bioequivalence of Valzan^® tablets a randomized, two-way, crossover, bioequivalence study was performed in 24 healthy male volunteers. The selected volunteers were divided into two groups of 12 subjects. One group was treated with the reference formulation (Diovan^®) and the other one with the generic Valzan^®, with a cross-over after the drug washout period of 14 days. Blood samples were collected at fixed time intervals and valsartan concentrations were determined by a validated HPLC assay method. The pharmacokinetic parameters AUC_0–48, AUC_0–∞, C_max, T_max, K_e and T_1/2 were determined for both the tablets and were compared statistically to evaluate the bioequivalence between the two brands of valsartan, using the statistical model recommended by the FDA. The analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals (CI) fell within the acceptable range for bioequivalence. Based on this statistical evaluation it was concluded that the test tablets (Valzan^®) is well formulated, since it exhibits pharmacokinetic profile comparable to the reference brand Diovan^®.     

尼莫地平口服固体制剂溶出度的研究

目的 测定尼莫地平口服固体制剂在不同溶出介质中的溶出度,并对测定方法进行评价.方法 采用0.25％十二烷基硫酸钠(SDS)、水、pH=1.2人工胃液、pH=4.5醋酸盐缓冲液、pH=6.8磷酸盐缓冲液作为溶出介质,测定尼莫地平的溶出度并绘制曲线.结果 尼莫地平片在含0.25％ SDS溶出介质中的溶出度与生物利用度不相关,而在其他溶出介质具有一定的相关性.结论 SDS掩盖了该制剂内在品质的表达,不能反映该制剂在体内的溶出情况;中国药典收载的溶出度方法可能难以满足本品的测定需要.     

Formulation design considerations for oral vaccines

Whilst oral vaccination is a potentially preferred route in terms of patient adherence and mass vaccination, the ability to formulate effective oral vaccines remains a challenge. The primary barrier to oral vaccination is effective delivery of the vaccine through the GI tract owing to the many obstacles it presents, including low pH, enzyme degradation and bile-salt solubilization, which can result in breakdown/deactivation of a vaccine. For effective immune responses after oral administration, particulates need to be taken up bythe M cells however, these are few in number. To enhance M-cell uptake, particle characteristics can be optimized with particle size, surface charge, targeting groups and bioadhesive properties all being considerations. Yet improved uptake may not translate into enhanced immune responses and formulating particulates with inherent adjuvant properties can offer advantages. Within this article, we establish the options available for consideration when building effective oral particulate vaccines.     

Lack of interaction between diazepam and nimodipine during chronic oral administration to healthy elderly subjects.

1. Nimodipine (30 mg three times daily) and diazepam (10 mg once daily), were given orally to 24 elderly healthy subjects in a randomized, non-blinded, threefold-crossover study. Each of the three treatment periods lasted 5 days separated by 2 week washout phases. 2. Plasma concentrations of nimodipine and diazepam were not affected by the combined treatment. 3. No clinically relevant changes in haemodynamics, ECG recordings, clinical chemistry or haematology were observed after all of the three treatments. The overall frequency of side effects was lowest during monotherapy with nimodipine and highest during diazepam monotherapy. 4. In the test of subjective rating of tiredness (VAS) and the Pauli calculation test, diazepam, alone and with nimodipine co-medication, produced an increase in tiredness and a clear reduction in performance and endurance. After nimodipine monotherapy an improvement was observed only in the Pauli test. Using the critical flicker fusion frequency test (CFF) significant decrements in performance were found after diazepam monotherapy only. 5. In summary, there was no evidence that either nimodipine or diazepam affected the pharmacokinetics, safety and tolerance of each other. However, the CNS-effects of diazepam were compensated partially by nimodipine.     

Formulation and evaluation of limonene-based membrane-moderated transdermal therapeutic system of nimodipine

The aim of the present study was to design a membranemoderated transdermal therapeutic system (TTS) of nimodipine using 2% w/w hydroxypropyl methylcellulose (HPMC) gel as a reservoir system containing 4% w/w of limonene as a penetration enhancer. The permeability flux of nimodipine through ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer (9 to 28%). The effect of pressure-sensitive adhesives such as TACKWHITE A 4MED® on the permeability of nimodipine through EVA membrane 2825 (28% w/w vinyl acetate) or membrane/rat skin composite also was studied. The permeability flux of nimodipine from the chosen EVA 2825 (with 28% vinyl acetate content) was 159.72 ± 1.96 μg/cm²/hr, and this flux further decreased to 141.85 ± 1.54 μg/cm²/hr on application of pressure-sensitive adhesive (TACKWHITE A 4MED®). However, the transdermal permeability flux of nimodipine across EVA 2825 membrane coated with TACKWHITE A 4MED®/rat skin composite was found to be 126.59 ± 2.72 μg/cm²/hr, which is 1.3-fold greater than the required flux. Thus, a new transdermal therapeutic system for nimodipine was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE 4A MED® and 2% w/w HPMC gel as reservoir containing 4% w/w of limonene as a penetration enhancer. The bioavailability studies in healthy human volunteers indicated that the TTS of nimodipine, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 20 hr with improved bioavailability in comparison with the immediate release tablet dosage form.     

Formulation and evaluation of diazepam hydrogel for rectal administration

Diazepam (DZP) has become a commonly used drug for treatment of acute repetitive epileptic seizures and febrile convulsions in children. Considering the advantages of rectal administration of DZP, the objective of our study was to formulate and evaluate rectal hydrogels containing DZP as a drug substance in combination with suitable co-solvents and preservatives. Prepared HPMC (hydroxypropyl methylcellulose) hydrogels containing different concentrations of DZP (2, 4 and 6 mg mL(-1)) manifested good quality in respect to physico-chemical parameters (pH value, drug content, ingredients content and viscosity), antimicrobial efficiency and microbiological quality. Under the proposed HPLC conditions, satisfactory separation of DZP and the preservatives used was achieved. In vitro release studies have shown that the total amount of DZP was released in a period of 3 h. Prepared formulations were stable for four months at 26 degrees C (ambient temperature characteristic of the 2nd climate zone).     

Effects of particle size on the pharmacokinetics of puerarin nanocrystals and microcrystals after oral administration to rat

Puerarin, which is extracted from traditional Chinese medicine, is widely used in clinic in China and mainly used as a therapeutic agent to cardiovascular diseases. Owing to its poor water solubility and adverse drug reactions caused by cosolvents after intravenous administration, the development of oral formulation is urgently needed. Nowadays, nanocrystals technique has become a preferred way to develop oral dosage form. In this study, we used high pressure homogenization (HPH) to prepare puerarin nanocrystals and microcrystals with different sizes ranged from 525.8 nm to 1875.6 nm and investigated the influence of particle size on pharmacokinetics. The nanocrystals and microcrystals prepared were characterized using DLS, DSC, XRD and SEM, and we found that the crystalline state of puerarin was changed during the preparation process and the drug was dispersed into HPMC. In the pharmacokinetic study, we observed an increasing of C_max and AUC and a decreasing of CL/F with the decreasing of particle size. The AUC of the puerarin nanocrystals (525.8 nm) was 7.6-fold of that of raw puerarin suspension, with an absolute bioavailability of 21.44%. From the above results, we can conclude that nanocrystal technique is an efficient technology to improve the oral bioavailability of puerarin.     

Formulation optimization and in vitro characterization of sertraline loaded self-nanoemulsifying drug delivery system (SNEDDS) for oral administration

Sertraline is a selective serotonin reuptake inhibitors used as major therapeutic advances in psychiatry and is drug of choice for treatment of major depressive disorders. The drug (free base) encounters problem of poor aqueous solubility and vulnerability to enzymatic degradation in liver. The hydrochloride salts of free base revert back to its original form in gastrointestinal tract leading to slow/poor absorption. In the current study, sertraline loaded self-nanoemulsifying drug delivery systems (SNEDDS) were prepared in an attempt to circumvent the problems associated with poor aqueous solubility, vulnerability to enzymatic degradation in liver and to sort out the problems associated with salt formation. Preliminary screening was carried out to select proper ingredient combinations. Ternary phase diagrams were then constructed and an optimum system was designated. Formulations selected were then compared for optimization. The systems were assessed for robustness, globule size, cloud point, percentage transmittance, surface morphology and drug release. An optimum system composed of oil (25.42?%), surfactant (49.72?%), and co-surfactant (24.86?%). It possessed a mean globule size, cloud point and percentage transmittance of 63.5?nm, 90?°C and 82.43?%, respectively. Transmission electron microscopy demonstrated spherical particle morphology. The drug release from the selected formulation was significantly higher than other SNEDDS and drug suspension as well. Optimized formulation was subjected to stability studies at different temperature and relative humidity and was found to be stable. No significant variations were observed in the formulation over a period of 3?months at accelerated conditions.     

Proliposomes of indomethacin for oral administration

Indomethacin, a non-steroidal anti-inflammatory drug was encapsulated into liposomes composed of soyabean lecithin, cholesterol and stearylamine for oral administration. Liposomes of homogenous size distribution and higher entrapment efficiency were derived from effervescent granule based proliposomes. The efficacy of the oral route was studied by measuring ulcerogenic index and anti-inflammatory activity using carrageenan induced paw oedema test in rats. The effervescent granule based liposomal products exhibited improved in vivo performance with reference to their cytoprotective and anti-inflammatory activities.     

Liposomes for oral administration of drugs

In the late 1970s liposome-entrapped insulin was administered by the oral route to both normal and diabetic animals. Results showed that small but significant amounts of insulin could reach the circulation. However, different liposome compositions gave varied results and no mechanism of absorption was elucidated. Subsequent in vitro studies suggested that many liposome compositions used were unstable in the conditions prevailing in the gastrointestinal tract. Using more stable liposomes in an everted gut system, it has been demonstrated that liposomes were pinocytosed by intestinal epithelial cells and transferred to the serosal side of the gut. Recent studies both in vitro and in vivo show that there may be the possibility of enhancing the uptake process to deliver a range of drugs by the oral route.     

Distribution of nimodipine in brain following intranasal administration in rats

AIM: To determine whether nasally applied nimodipine (NM) could improve its systemic bioavailability and be transported directly from the nasal cavity to the brain. METHODS: NM was administered nasally, intravenously (iv), and orally to male Sprague-Dawley rats. At different times post dose, blood, cerebrospinal fluid (CSF), and brain tissue samples were collected, and the concentrations of NM in the samples were analyzed byHPLC. RESULTS: Oral systemic bioavailability of NM in…     

Formulation of poorly water-soluble drugs for oral administration: physicochemical and physiological issues and the lipid formulation classification system.

Poorly water-soluble drug candidates often emerge from contemporary drug discovery programs, and present formulators with considerable technical challenges. The absorption of such compounds when presented in the crystalline state to the gastrointestinal tract is typically dissolution rate-limited, and the drugs are typically BCS class II or class IV compounds. Class IV compounds, which have low membrane permeability as well as poor aqueous solubility, are often poor candidates for development, unless the dose is expected to be low. The rate and extent of absorption of class II compounds is highly dependent on the performance of the formulated product. These drugs can be successfully formulated for oral administration, but care needs to be taken with formulation design to ensure consistent bioavailability. Essentially the options available involve either reduction of particle size (of crystalline drug) or formulation of the drug in solution, as an amorphous system or lipid formulation. The performance of amorphous or lipid formulations is dependent on their interaction with the contents of the gastrointestinal tract, therefore, a formulation exercise should involve the use of techniques which can predict the influence of gut physiology. A major consideration is the fate of metastable supersaturated solutions of drug, which are formed typically after dispersion of the formulation and its exposure to gastrointestinal digestion. A better understanding of the factors which affect drug crystallization is required, and the introduction of standardised predictive in vitro tests would be valuable. Although many bioavailability studies have been performed with poorly water-soluble drugs, thus far this research field has lacked a systematic approach. The use of a lipid formulation classification system combined with appropriate in vitro tests will help to establish a database for in vitro-in vivo correlation studies.     

Eplerenone nanocrystals engineered by controlled crystallization for enhanced oral bioavailability

Poor aqueous solubility of eplerenone (EPL) is a major obstacle to achieve sufficient bioavailability after oral administration. In this study, we aimed to develop and evaluate eplerenone nanocrystals (EPL-NCs) for solubility and dissolution enhancement. D-optimal combined mixture process using Design-Expert software was employed to generate different combinations for optimization. EPL-NCs were prepared by a bottom-up, controlled crystallization technique during freeze-drying. The optimized EPL-NCs were evaluated for their size, morphology, thermal behavior, crystalline structure, saturation solubility, dissolution profile, in vivo pharmacokinetics, and acute toxicity. The optimized EPL-NCs showed mean particle size of 46.8 nm. Scanning electron microscopy revealed the formation of elongated parallelepiped shaped NCs. DSC and PXRD analysis confirmed the crystalline structure and the absence of any polymorphic transition in EPL-NCs. Furthermore, EPL-NCs demonstrated a 17-fold prompt increase in the saturation solubility of EPL (8.96 vs. 155.85 µg/mL). The dissolution rate was also significantly higher as indicated by ∼95% dissolution from EPL-NCs in 10 min compared to only 29% from EPL powder. EPL-NCs improved the oral bioavailability as indicated by higher AUC, C_max, and lower T_max than EPL powder. Acute oral toxicity study showed that EPL-NCs do not pose any toxicity concern to the blood and vital organs. Consequently, NCs prepared by controlled crystallization technique present a promising strategy to improve solubility profile, dissolution velocity and bioavailability of poorly water-soluble drugs.     

New oral solid dosage form for furosemide oral administration

Furosemide (FURO) is a drug labeled in class IV of the Biopharmaceutics Classification System (BCS) as it is both poor soluble and poor permeable. The aim of this work was to improve FURO biopharmaceutical properties by its formulation in a new solid oral dosage form. It consists in the realization of the composite MgAl-HTlc-FURO, obtained by FURO intercalation into the inorganic matrix hydrotalcite (MgAl-HTlc), and its successive formulation in tablets intended to be swallowed whole and to disintegrate rapidly in the stomach. These formulations were prepared by direct compression of a simple powder mixture constituted by MgAl-HTlc-FURO, a super disintegrant (Explotab, PolyplasdoneXL, PolyplasdoneXL-10, PolyplasdoneINF 10 or L-HPCLH-21) and a filler. The prepared formulations were submitted to disintegration time tests, and only those displaying the lowest disintegration time in gastric medium were submitted to in vitro release studies. Drug dissolution profiles from MgAl-HTlc-FURO tablets were compared with those containing crystalline FURO alone or physically mixed to MgAl-HTlc instead of MgAl-HTlc-FURO. The results revealed that tablets containing MgAl-HTlc-FURO give the best dissolution profile and that L-HPCLH-21 is able to promote the highest drug release in gastric medium, resulting in the most suitable super disintegrant in comparison with the other tested.