Oral Dispersible System: A New Approach in Drug Delivery System

Dosage form is a mean used for the delivery of drug to a living body. In order to get the desired effect the drug should be delivered to its site of action at such rate and concentration to achieve the maximum therapeutic effect and minimum adverse effect. Since oral route is still widely accepted route but having a common drawback of difficulty in swallowing of tablets and capsules. Therefore a lot of research has been done on novel drug delivery systems. This review is about oral dispersible tablets a novel approach in drug delivery systems that are now a day''s more focused in formulation world, and laid a new path that, helped the patients to build their compliance level with the therapy, also reduced the cost and ease the administration especially in case of pediatrics and geriatrics. Quick absorption, rapid onset of action and reduction in drug loss properties are the basic advantages of this dosage form.     

蒙花苷磷脂复合物的制备及其药动学评价

目的 制备蒙花苷磷脂复合物，研究其药动学性质。方法 溶剂挥发法制备蒙花苷磷脂复合物，以复合率为评价指标，通过正交试验优化制备工艺。SD大鼠灌胃给予蒙花苷磷脂复合物，HPLC测定蒙花苷的血药浓度。结果 采用优化后的磷脂复合物制备工艺，复合率接近100%。X射线衍射结果表明蒙花苷以无定型状态存在于磷脂复合物中，在水和正辛醇中的表观溶解度显著增大。药动学结果显示，蒙花苷磷脂复合物的t_max，C_max，AUC_0-t等参数与蒙花苷原料药相比具有显著性差异，口服吸收生物利用度提高1.11倍。结论 磷脂复合物改善了蒙花苷的溶解性质，口服吸收生物利用度得到明显提高。     

Prediction of steady state bioequivalence relationships using single dose data II-nonlinear kinetics

Two nonlinear pharmacokinetic models were simulated to investigate the relationship between single and multiple dose bioequivalency parameters for drugs such as phenytoin and propranolol which exhibit either saturable elimination kinetics or a capacity limited first pass effect. Mean Tmax, Cmax and area under the plasma-concentration time curve values from 0 to infinity (AUC 0-infinity) were compared after a single and multiple dose(s) of a test or reference drug. The aim was to determine if there were systematic changes in the limits of the single dose confidence interval at steady state that would limit the usefulness of confidence intervals following a single dose in accurately predicting bioavailability following multiple dosing. The 90 per cent confidence interval expressed as a percentage of the reference mean for Tmax, Cmax, and AUC 0-infinity showed model dependent changes from single to multiple dosing in response to the level of data error and changes in absorption. Changes in clearance also seemed to have a marked effect on the observed limits of the single and multiple dose confidence intervals especially for Cmax which showed a characteristic change in the intervals as a function of the clearance ratio. The model used to describe phenytoin had confidence intervals for Cmax and AUC 0-infinity from single to multiple dosing that were similar to that seen for the experimental data. However, the model predictions for Tmax confidence intervals following single and multiple dosing was at variance with the experimental data for formulations A and B.     

In Vitro and in Vivo Evaluation of Whole and Half Tablets of Sustained-Release Adinazolam Mesylate

The mechanism of release from sustained-release adinazolam mesylate tablets was assessed by the Higuchi equation and by analysis of drug release profiles through 60% released using the Peppas equation. Computed values of the diffusional exponent, n, ranged from 0.59 to 0.66. Values of n in this range are consistent with a mixed mechanism of release, with diffusion of drug through the hydrated polymer matrix and relaxation of this matrix being the principal processes controlling release. The rate of in vitro drug release was increased for half tablets relative to whole tablets and is attributed to an increase in the surface to volume ratio of half tablets of about 16%. This increase in surface-to-volume ratio of half tablets was reflected by an increase in the constant, k, from the Peppas equation of 20–23% and by an increase in the slope of Higuchi plots of 12–18% for four lots of tablets. In vivo/in vitro relationships from two bioavailability studies were thoroughly evaluated. Using either a linear or a quadratic relationship, an in vivo/in vitro correlation exists for sustained-release adinazolam mesylate tablets.     

Bioavailability and Pharmacokinetics of a New Sustained-Release Potassium Chloride Tablet

The bioavailability of a new sustained-release potassium chloride (KC1) tablet, designed for once-a-day dosing, was compared to a KC1 elixir using urinary excretion data. The study utilized 25 male volunteers dosed in a crossover design in a dietary/activity-controlled environment. The regimens consisted of a total of 80 mEq of potassium in three equally divided doses of elixir every 6 hr and a single 80-mEq dose using four 20-mEq sustained-release (SR) tablets. The mean time to maximum rate of potassium urinary excretion was 2.2 hr for the first elixir dose and 5.5 hr after the SR tablet (P < 0.01), thereby supporting the prolonged-release properties of this formulation. After correction for baseline urinary potassium excretion, the mean total 24-hr urinary potassium excretion was 42.18 mEq for the elixir and 40.41 mEq for the SR tablet. The results indicate that the absorption pattern from the SR tablet is equal to three doses of KC1 elixir dosed 6 hr apart.     

Comparative kinetics of phenobarbital after administration of the acid and the propylhexedrine salt (barbexaclone)

Summary The kinetics of phenobarbital (PB) was compared after oral administration of equivalent doses of the drug as the acid or the propylhexedrine salt (barbexaclone) to 7 normal volunteers. The absorption and elimination parameters were very similar. It was concluded that propylhexedrine did not affect the serum kinetics of PB given as barbexaclone.     

枢复宁在肺癌患者体内的药物动力学和生物利用度

９名接受顺铂化疗的原发性肺癌患者单次口服和静脉注射枢复宁８ｍｇ后，用反相高效液相色谱法测定血浆药物浓度。经用ＰＫＢＰ－Ｎ１程序在计算机上拟合计算表明，枢复宁在人体内表现为二房室模型。口服后主要药动学参数：Ｔ１／２Ｋａ＝０．４１±０．３０ｈ，Ｔ１／２α＝０．９±０．４３ｈ，Ｔ１／２β＝３．３±１．２ｈ，Ｃｍａｘ＝２８．６±９．５ｎｇ／ｍｌ，Ｔｍａｘ＝１．７±０．９ｈ，ＡＵＣ＝１５８±７３ｎｇ·ｈ／ｍｌ，绝对生物利用度为５５％。     

A Comparison of Oral and Rectal Absorption of L-Dopa Esters in Rats and Mice

Short-chain alkyl esters of L-dopa were administered to rats and mice via oral and rectal routes. Plasma L-dopa esters and L-dopa were determined in the systemic and portal circulation by HPLC. A comparison of isopropyl, butyl, and 4-hydroxybutyl esters of L-dopa demonstrated significantly higher levels of the esters in both systemic and portal blood samples following rectal administration than following oral administration. In most cases, oral administration resulted in nondetectable (<0.01 µg/ml) levels of the esters in plasma. Correspondingly, the plasma levels of L-dopa itself were consistently higher following rectal administration. At very high oral doses (500 mg L-dopa equivalents/kg body weight), systemic plasma levels of the butyl ester could be detected (1.25 µg/ml at 10 min), which might indicate saturation of the esterase activity of the small intestine. These studies indicate that the systemic availability of L-dopa from short-chain alkyl esters of L-dopa may be best optimized by rectal administration, which avoids the relatively high esterase activity characteristic of the small intestine.     

雷公藤双层栓的研制

介绍了雷公藤双层栓的制备和质量检查。雷公藤双层栓的上层为空白层,下层为含药层。空白层可有效地阻止后端所释药物向上扩散,从而避免相当部分药物经门肝系统吸收,因此可明显提高其生物利用度。     

Formulation and in Vitro-in Vivo Evaluation of Sustained-Release Lithium Carbonate Tablets

The release of lithium carbonate incorporated into polymethylmethacrylate, poly vinyl chloride, hy-drogenated vegetable oil, and carbomer matrix tablets was studied in vitro. The formulation containing 10% carbomer showed a sustained-release profile comparable to that of a standard, commercially available, sustained-release preparation containing 400 mg lithium carbonate embedded in a composite material. In vivo the newly formulated and standard sustained-release lithium carbonate tablets were compared to an oral solution and conventional lithium carbonate tablets in 12 healthy subjects. These crossover studies showed that the sustained-release tablets produced a flatter serum concentration curve than the oral solution and conventional tablet, without loss of total bioavailability.