法莫替丁缓释微丸的悬浮包衣法制备

采用淀粉和蔗糖为赋形剂制备法莫替丁含药微丸，以乙基纤维素为包衣材料，采用悬浮包衣法制备了法莫替丁缓释微丸，并用正交设计筛选出了最佳制备工艺参数。释放度研究结果表明：在进风温度为45℃，喷雾压力为147kPa及输液速度为10ml/min的条件下进行包衣，可制得在12h内释药符合Higuchi模型动力学过程的缓释微丸。     

挤出-滚圆和流化床包衣法制备盐酸二甲双胍肠溶微丸

目的研制盐酸二甲双胍肠溶微丸。方法采用挤出-滚圆工艺和流化床包衣法制备,用正交试验设计优化处方,考察产品的体外释放度。结果制得的盐酸二甲双胍肠溶微丸圆整度高、收率高、体外释放度好。结论所用制备工艺简单易行,重现性好。     

Processing Considerations for an EC Latex Coating System: Influence of Curing Time and Temperature

The influence of curing time and curing temperature for a commercially available ethylcellulose latex coating dispersion (Aquacoat^®) were evaluated using response surface methodology. Levels for the factor curing time ranged from 30 to 300 minutes while levels for curing temperature ranged from 45° to 75°C. Responses, A, , and , were derived from regression analysis of the dissolution profiles and correspond to the maximum amount of drug released over the 12 hour sampling period, the rate of release, and the inflection point of the dissolution profile, respectively. The nature of the response surface was dramatically influenced by the plasticizer incorporated into the coating formula. When dibutyl sebacate was employed as the plasticizer, faster release resulted (higher A and values, lower values) when samples were exposed to higher curing temperatures or were stored for longer periods of time. Paradoxically, when tributyl citrate was used as the plasticizer, slower release resulted when samples were exposed to more rigorous conditions. Overall, curing temperature had a more dramatic effect than curing time.     

Comparative pharmacokinetics of sodium- and methylglucamine diatrizoate in urography

Summary Comparative tests were carried out, using a radioactive tracer method, on the pharmacokinetics of sodium and methylglucamine diatrizoate. A biological model was simulated using an analogue computer; and the rate and elimination constants, the elimination half life, and the ratio of tissue entry to tissue elimination constants were calculated. Over the period of time required for X-ray diagnosis, the two salts of the contrast medium acid which were tested did not alter the pharmacokinetics of the contrast medium itself.     

Pharmacokinetics of phenprocoumon in man investigated using a gas chromatographic method of drug analysis

Summary A gas chromatographic method for the determination of phenprocoumon (Marcumar^®) in serum and urine is described, which facilitates accurate values down to 0.5 g phenprocoumon/ml serum. After the i.v. administration of 20 mg phenprocoumon in a single dose to 4 healthy volunteers the following pharmacokinetic data were obtained:After the initial fast decrease (phase 1) of the serum level of phenprocoumon, probably due to the distribution into the different compartments is followed by a subsequent slower fall (phase 2) which occurs with a serum half-life of 157 h. The apparent distribution volume was 6.51. Analysis of the urine demonstrated that 90% of the excreted phenprocoumon detected was in the glucuronide form.This study was supported by a grant from the Deutsche Forschungsgemeinschaft.Preliminary reports were presented on March, 19, 1973 at the 14th Spring Meeting of the Deutsche Pharmakologische Gesellschaft in Mainz and on May 2, 1973 at the 79th Congress of the Deutsche Gesellschaft für innere Medizin in Wiesbaden.     

Hepatic Uptake of Octreotide,a Long-Acting Somatostatin Analogue,via a Bile Acid Transport System

The hepatic transport mechanism of octreotide (Sandostatin^®), a somatostatin analogue, was studied using freshly prepared rat hepatocytes. The initial uptake rate of octreotide represented exclusively a saturable transport process. The half-saturation constant, K_t, and the maximum uptake-rate, J_max, for the uptake of octreotide were 91.1 ± 28.4 µM and 104.6 ± 19.7 pmol/mg protein/min, respectively. An energy requirement was demonstrated for [¹⁴C]octreotide uptake since metabolic inhibitors (DNP, rotenone, antimycin and NaCN) significantly reduced the initial uptake rate. [¹⁴C]octreotide uptake was also significantly inhibited by ouabain. [¹⁴C]octreotide uptake was reduced in the absence of Na⁺ in the uptake medium. [¹⁴C]octreotide uptake was significantly inhibited by bile acids, iodipamide, d-tubocurarine, whereas it was not inhibited by bilirubin, TEMA and insulin. Competitive inhibition of taurocholic acid was observed for octreotide uptake with the inhibition constant, K_i, of 82 ± 17 µM. Moreover, a significant inhibitory effect of octreotide was observed for the Na ⁺ dependent uptake of [¹⁴C]taurocholic acid. These results suggest that octreotide is transported into hepatocytes via a bile acid carrier-mediated system.     

Attempted treatment of tri-ortho-cresyl phosphate intoxication with a water-soluble protein-free extract of mammalian heart muscle

Recosen^® protects cocks from paralysis caused by tri-ortho-cresyl phosphate.This work was supported by a Grant (No 869-1/72) from the Foundation for Scientific Research of the Republic Bosnia and Herzegovina.     

Gene markers in dendritic cells unravel pieces of the skin sensitization puzzle

The underlying events of how dendritic cells (DC) are capable of evoking an antigen-specific skin sensitization response are not yet understood. Recently, we revealed a set of genes in human cord blood CD34⁺ DC (CD34-DC) that show a discriminating behaviour after skin sensitizing exposure. Based on their differential expression, an in vitro assay was developed to identify chemicals as sensitizing or not.     

Comparative Tissue Distribution and Elimination of Amphotericin B Colloidal Dispersion (Amphocil®) and Fungizone® After Repeated Dosing in Rats

The pharmacokinetic profiles of amphotericin B (AmB) after administration of Amphocil^®, an AmB/cholesteryl sulfate colloidal dispersion (ABCD) and the micellar AmB/deoxycholate (Fungizone^®) were compared after repeated dosing in rats. After administration of ABCD and Fungizone at an equal AmB dose (1 mg/kg), AmB concentrations in plasma and most tissues were lower for the ABCD dose, especially in the kidneys where reduced drug concentration correlated with reduced nephrotoxicity. In contrast, AmB concentrations in the liver were substantially higher when ABCD was administered; however, without an accompanying increase in hepato-toxicity. Daily administration of ABCD for 14 days did not lead to AmB accumulation in plasma; while a slight accumulation was observed after multiple administration of Fungizone. AmB was eliminated more slowly from the plasma and various tissues and urinary and fecal recoveries of AmB were reduced after ABCD administration. These results suggest that ABCD may be stored in tissues in a form that is less toxic and is eliminated from the systemic circulation by a different mechanism than the free and protein-bound AmB in plasma. AmB accumulation in the spleen was observed when higher doses of ABCD (5 mg/kg) were administered, which could be due to saturation of hepatic uptake of AmB. Comparison of spleen concentrations of AmB between ABCD and Fungizone^® at 5 mg/kg AmB doses was not possible because of Fungizone's toxicity in rats. In all other organs, AmB concentrations reached or approached a steady state within two weeks of dosing with ABCD. Urinary and fecal clearances of AmB were not different between ABCD and Fungizone administration. In summary, the distribution and elimination characteristics of AmB in rats were substantially altered when it was administered as ABCD in comparison to Fungizone. Nephrotoxicity of AmB in rats was reduced after administration of ABCD apparently because of the altered tissue distribution pattern. Thus, ABCD (Amphocil^®) may be a clinically beneficial formulation of AmB in patients with systemic fungal infections.     

Immobilization of Russian VX skin depots by localized cooling: implications for decontamination and medical countermeasures

The chemical weapon nerve agent known as Russian VX (VR) is a potent organophosphorus (OP) compound that is much less studied than its VX analogue with respect to toxicity, as well as to the effectiveness of several known countermeasures against it. An anaesthetized domestic swine model was utilized to assess several approaches in mitigating its toxicity, including the utility of cooling VR treated skin to increase the therapeutic window for treatment. The 6 h LD₅₀ for VR topically applied on the ear was 100 μg/kg. Treatment of VR exposed animals (5× LD₅₀) with pralidoxime (2PAM) very poorly regenerated inhibited blood cholinesterase activity, but was partially effective in preventing signs of OP poisoning and increasing survival. In contrast, treatment with the Hagedorn oxime HI-6 reactivated cholinesterase, eliminated all signs of poisoning and prevented death. Decontamination with the Reactive Skin Decontaminant Lotion (RSDL) 15 min after VR exposure was completely effective in preventing death. Cooling of the VR exposure sites for 2 or 6 h prevented signs of OP poisoning and death during the cooling period. However, these animals died very quickly after the cessation of cooling, unless they were treated with oxime or decontaminated with RSDL. Blood analyses showed that cooling of agent exposure sites delayed the entry of VR into the bloodstream. Medical treatment with HI-6 and to a lesser extent 2PAM, or decontamination with RSDL are effective in protecting against the toxic effects of cutaneous exposure to VR. Immobilizing this agent (and related compounds) within the dermal reservoir by cooling the exposure sites, dramatically increases the therapeutic window in which these medical countermeasures are effective.     

The therapeutic use of localized cooling in the treatment of VX poisoning

The organophosphate (OP) nerve agent VX is a weaponized chemical warfare agent that has also been used by terrorists against civilians. This contact poison produces characteristic signs of OP poisoning, including miosis, salivation, mastication, dysrhythmias and respiratory distress prior to death. Although successful treatment of OP poisoning can be obtained through decontamination and/or oxime reactivation of agent-inhibited cholinesterase, medical countermeasures that increase the therapeutic window for these measures would be of benefit. An anaesthetized swine model was utilized to examine the effects of lethal VX exposure to the skin, followed by cooling the exposure site prior to decontamination or treatment. The cooling was simply accomplished by using crushed ice in grip-seal plastic bags applied to the exposure sites. Cooling of skin exposed to lethal doses of VX significantly increased the window of opportunity for successful decontamination using the Reactive Skin Decontaminant Lotion^® (RSDL^®) or treatment with the oxime antidotes HI-6 and 2PAM. Analyses of blood VX levels showed that cooling acted to slow or prevent the entry of VX into the bloodstream from the skin. If the exposure site is known, the simple and non-invasive application of cooling provides a safe means with which to dramatically increase the therapeutic window in which decontamination and/or antidote treatment against VX are life-saving.     

Baclofen ester and carbamate prodrug candidates: a simultaneous chromatographic assay, resolution optimized with DryLab

Baclofen exhibits insufficient CNS-availability when dosed systemically. Hence, prodrug candidates (methyl, ethyl, 1-propyl, 2-propyl and butyl 4-(tert-butoxycarbonyl amino)-3-(4-chlorophenyl) butanoate) were synthesized aiming at CNS-levels appropriate for the treatment of spastic disorders. The characterization of some biopharmaceutically highly relevant physicochemical properties (Log P and aqueous solubility) and the evaluation of biophase levels represent one important component of the project. The overall research aim was to generate an HPLC optimized method using DryLab^®, a simulation software for the optimization of a RP-HPLC method, which was optimized using a simulation software (DryLab^®), for the simultaneous determination of baclofen and ten synthesized prodrug candidates. The chromatographic resolution predicted and obtained via the simulation is Rs >1.5 for all baclofen derivatives, as well as, with parent baclofen. The method was used to assay the prodrugs and determine their purities, solubility and lipophilicity parameters. The designed analytical method also permits the tracking of the new prodrug candidates’ hydrolysis in vitro and in vivo. The determined physicochemical properties indicate for some of the compounds that they might be suitable for CNS-targeting which was exemplified by the detection of significant baclofen levels in rat brain tissues following an i.p. dose of ethyl carbamate (vs. ethyl ester, for which only traces of baclofen were detected).     

Recent Advances in Brain Tumor Therapy: Local Intracerebral Drug Delivery by Polymers

New approaches to malignant glioma are being actively investigated. Local drug delivery directly to the site of the tumor is one novel approach that has been approved by the US FDA and other regulatory agencies worldwide. This agent, Gliadel, delivers the chemotherapeutic drug carmustine (BCNU) from a biodegradable polymer placed in the resection cavity after brain tumor surgery. Gliadel represents the first clinical application of polymer delivery for brain tumors, but the potential for this new methodology is far greater. In this review, we will briefly summarize the development of Gliadel from a laboratory idea to its current role as an approved treatment for gliomas. Then we will present the most recent work being done to expand the potential benefits of polymeric delivery for brain tumors. This work includes trials for its use as the initial therapy for gliomas, as well as its use against metastasis. Further clinical trials exploring the maximum-tolerated dose and the combination of Gliadel with systemic chemotherapeutic treatments such as temozolamide and O(6)-benzylguanine will be reviewed. Finally, we will present preclinical work on the efficacy of polymeric methods for delivering other chemotherapeutic agents, and a variety of novel compounds that modify brain tumor biology. This latter work represents potential future clinical applications of local polymeric drug delivery to the brain and other sites where cancers can occur.     

Development and validation of a reversed-phase HPLC method for the simultaneous analysis of simvastatin and tocotrienols in combined dosage forms

A RP-HPLC method for the simultaneous analysis of tocotrienol isoforms (TRF) and simvastatin (SIM) in SIM–TRF nanoparticles (NPs) was developed. Analytes were monitored by UV detection at 238 and 295 nm for SIM and TRF, respectively, using a gradient methanol/water elution. Calibration curves for TRF and SIM were linear over concentration range of 20–80 μg/mL and 1–10 μg/mL with correlation coefficients 0.9990 and 0.9991, respectively. The recovery of TRF and SIM from the NPs was in the range from 97.35 to 102.19% and from 92.71 to 104.35%, respectively. This developed method was successfully employed in quantifying both drugs in NPs for future use in cancer therapy.     

Extinction with varenicline and nornicotine, but not ABT-418, weakens conditioned responding evoked by the interoceptive stimulus effects of nicotine

The interoceptive stimulus effects of nicotine acquire control over behavior. This observation, among others, suggests that the stimulus effects of nicotine are important in the development and tenacity of tobacco dependence. Despite this importance, there has been little research examining whether non-reinforced presentations (extinction) of a ligand that share stimulus effects of nicotine will weaken responding controlled by nicotine. Rats were trained to discriminate nicotine (0.4 mg/kg) from saline using a discriminated goal-tracking task in which nicotine signaled intermittent access to sucrose; sucrose was withheld on saline sessions. Experiment 1 examined substitution for nicotine by ABT-418, nornicotine, epibatidine, varenicline, or cytisine in 4-min extinction tests. Experiments 2–5 [low-dose nicotine (0.05 mg/kg), ABT-418, nornicotine, or varenicline, respectively] examined whether substitution for nicotine would persist if extinction tests were increased to 20 min and repeated daily for 6 days. Finally, generalization of this extinction back to the nicotine training stimulus was assessed. Full substitution in brief 4-min extinction tests was seen for ABT-418, nornicotine, epibatidine, varenicline, and cytisine. Low-dose nicotine, ABT-418, nornicotine, and varenicline, evoked only a partial ‘nicotine-like’ response in the first 20-min extinction test. With repeated extinction, only low-dose nicotine, nornicotine, and varenicline continued to substitute. Extinction with nornicotine and varenicline transferred back to nicotine as indicated by a partial conditioned response to the training stimulus. Interpretations regarding ‘nicotine-like’ effects of a ligand depend on the nature of the test. Understanding the processes mediating transfer of extinction learning with potential pharmacotherapies may reveal new treatment targets.     

Quantitative Prediction of the Bitterness Suppression of Elemental Diets by Various Flavors Using a Taste Sensor

PURPOSE: The purpose of the study was to develop a method for the quantitative prediction of the bitterness suppression of elemental diets by various flavors and to predict the optimum composition of such elemental diets for oral administration using a multichannel taste sensor. METHODS: We examined the effects of varying the volume of water used for dilution and of adding varying quantities of five flavors (pineapple, apple, milky coffee, powdered green tea, and banana) on the bitterness of the elemental diet, Aminoreban EN. Gustatory sensation tests with human volunteers (n = 9) and measurements using the artificial taste sensor were performed on 50 g Aminoreban EN dissolved in various volumes (140), 180, 220, 260, 300, 420, 660, 1140, and 2100 ml) of water, and on 50 g Aminoreban EN dissolved in 180 ml of water with the addition of 3-9 g of various flavors for taste masking. RESULTS: In gustatory sensation tests, the relationship between the logarithmic values of the volumes of water used for dilution and the bitterness intensity scores awarded by the volunteers proved to be linear. The addition of flavors also reduced the bitterness of elemental diets in gustatory sensation tests; the magnitude of this effect was, in decreasing order, apple, pineapple, milky coffee, powdered green tea, and banana. With the artificial taste sensor, large changes of membrane potential in channel 1, caused by adsorption (CPA values, corresponding to a bitter aftertaste), were observed for Aminoreban EN but not for any of the flavors. There was a good correlation between the CPA values in channel 1 and the results of the human gustatory tests, indicating that the taste sensor is capable of evaluating not only the bitterness of Aminoreban EN itself but also the bitterness-suppressing effect of the five flavors, which contained many elements such as organic acids and flavor components, and the effect of dilution (by water) on this bitterness. Using regression analysis of data derived from the taste sensor and from human gustatory data for four representative points, we were able to predict the bitterness of 50 g Aminoreban EN solutions diluted with various volumes of water (14-300 ml), with or without the addition of a selected flavor. CONCLUSIONS: Even though this prediction method does not offer perfect simulation of human taste sensations, the artificial taste sensor may be useful for predicting the bitterness intensity of elemental diets containing various flavors in the absence of results from full gustatory sensation tests.     

Inhibition of lymphocyte response to mitogens by dipyridamole: Preliminary findings

Summary It has been recently noted that dipyridamole (DP) may be involved in certain immunological reactions, in addition to its antiplatelet action. In the present investigation the mitogenic response of human lymphocytes from three groups of subjects to 3 different lectins was examined. In both the experimental group treated over a short period and in the controls a highly significant decrease in the mean lymphocyte response to all 3 mitogens was noted following 3 days of DP administration. The response remained low after an additional 3 days of treatment. Discontinuation of drug administration was followed by a significant increase in response to two mitogens, concanavalin A (Con A) and pokeweed mitogen (PWM). The response to phytohaemagglutinin (PHA) extent only increased to a small, non-significant. No change in the mean mitogenic response was detected in the group undergoing long-term treatment. The mechanism by which DP alters lymphocyte activity is as yet unknown.     

Characterization of diffusion and duration of action of a new botulinum toxin type A formulation

RT002, an injectable form of botulinum neurotoxin type A (BoNTA), comprised of a purified 150 kDa neurotoxin formulated in a novel formulation, is designed to limit the extent of diffusion and permit safe administration of longer acting doses. The aim of this study was to evaluate the degree of diffusion of RT002 in comparison to another commercially available BoNTA product, Botox^® Cosmetic (OnabotulinumtoxinA, Allergan, Inc., Irvine, CA, USA), and establish the relative duration of effect for diffusion matched doses of the two BoNTA formulations using quantitative measurements in mice.Measurement of muscle paralysis by muscle force generation (MFG) in mice at the injected gastrocnemius muscles indicated that RT002 and Botox are equipotent. Measurements of MFG inhibition in an adjacent muscle, the tibialis anterior muscle, indicated significantly less diffusion for RT002 as compared to Botox. When RT002 and Botox were dosed using the established diffusion matched doses, RT002 treatment resulted in an extended duration of drug effect as compared to Botox by 58-100% as assessed by either partial or complete recovery endpoints. Use of a daily voluntary running activity model provided confirmation that the two BoNTA formulations are equipotent by daily running distance and further confirmed the diffusion matched dose ratio assessed by degree of drug effect on body weight gain. Using these diffusion matched doses, RT002 treatment resulted in an extended duration of drug effect as compared to Botox (100-126% increase in duration) as assessed by either partial or complete recovery endpoints. Use of this model provides further evidence that the RT002 formulation limits diffusion with equipotency and thereby may permit safe administration of higher and more efficacious doses. In summary, data from two murine models suggest that RT002 may represent a next generation of BoNTA drug formulation offering superior degree and duration of effect at the intended target while controlling the unwanted diffusion and accompanying adverse effects of BoNTA at neighboring muscles and distal systemic targets.     

Development and validation of HPLC method for the determination of Cyclosporin A and its impurities in Neoral capsules and its generic versions

Cyclosporin A (CyA) is a cornerstone immunosuppressant for the prophylaxis against allograft rejection after organ transplantation. The most widely prescribed CyA formulation is Neoral^® soft gelatine capsules (Novartis Pharmaceuticals, Basel, Switzerland). After Novartis patent expiration, several generic formulations have been developed.