Influence of amount of hard fat in suppositories on the in vitro release rate and bioavailability of paracetamol and codeine. I. A comparison of three suppository compositions in vivo

1994 ◽  
Vol 102 (1-3) ◽  
pp. 71-80 ◽  
Author(s):  
Kirsti Gjellan ◽  
Christina Graffner ◽  
Hans Quiding

Fig. 12 Scanning electron micrograph of D.L-PLA nanoparticles loaded with CGP 57813. (Ref. 51.) scanning force microscopy (also called atomic force microscopy), enable the visualiza-tion of nanoparticles at atmospheric pressure without gold coating [12,64]. Neverthe-less, the resolution obtained with these new tools is still lower than that with SEM. For size determination, transmission electron microscopy is not as widely used as PCS and SEM, but it is still a powerful method for determining the morphology of particles. With this technique, Fessi et al. [42] estimated the wall thickness of PLA nanocapsules. Krause et al. [18] described the highly porous structure of PLA nano-spheres prepared by the emulsion-evaporation procedure. VIII. IN VITRO RELEASE STUDIES In vitro release studies should in principle be useful for quality control as well as for the prediction of in vivo kinetics. Unfortunately, due to the very small size of the par-ticles, the release rate observed in vivo can differ greatly from the release obtained in a buffer solution. However, in vitro release studies remain very useful for quality control as well as for evaluation of the influence of process parameters on the release rate of active compounds. In vitro drug release from microdispersed systems has been exten-sively reviewed by Washington [65]. Depending on the type of polyester, drug release from nanoparticles can take place through several processes, of which the following appear to be the most important: (1) The drug may diffuse out of the carrier through the solid matrix; to allow complete release from the carriers, (the concentration of drug in the release medium should re-main infinitely low, which condition is known as sink condition); (2) The solvent may penetrate the nanoparticles and dissolve the drug, which then diffuses out into the re-lease medium. Depending on the physico-chemical characteristics of the particles, wa-ter can enter the particles through narrow pores or by hydration. Once the drug is dis-solved, the drug diffuses out of the particles. Here again, since diffusion is driving the

1998 ◽  
pp. 204-216

1997 ◽  
Vol 2 (1) ◽  
pp. 11-24 ◽  
Author(s):  
Gurvinder Singh Rekhi ◽  
Natalie D. Eddington ◽  
Michael J. Fossler ◽  
Paul Schwartz ◽  
Lawrence J. Lesko ◽  
...  

1987 ◽  
Vol 57 (02) ◽  
pp. 201-204 ◽  
Author(s):  
P Y Scarabin ◽  
L Strain ◽  
C A Ludlam ◽  
J Jones ◽  
E M Kohner

SummaryDuring the collection of samples for plasma β-thromboglobulin (β-TG) determination, it is well established that artificially high values can be observed due to in-vitro release. To estimate the reliability of a single β-TG measurement, blood samples were collected simultaneously from both arms on two separate occasions in 56 diabetic patients selected for a clinical trial. From each arm, blood was taken into two tubes containing an anticoagulant mixture with (tube A) and without (tube B) PGE!. The overall mean value of B-TG in tube B was 1.14 times higher than in tube A (p <0.01). The markedly large between-arms variation accounted for the most part of within-subject variation in both tubes and was significantly greater in tube B than in tube A. Based on the difference between B-TG values from both arms, the number of subjects with artifically high B-TG values was significantly higher in tube B than in tube A on each occasion (overall rate: 28% and 14% respectively). Estimate of between-occasions variation showed that B-TG levels were relatively stable for each subject between two occasions in each tube. It is concluded that the use of PGEi decreases falsely high B-TG levels, but a single measurement of B-TG does not provide a reliable estimate of the true B-TG value in vivo.


Author(s):  
Chukwuebuka Umeyor ◽  
Uchechukwu Nnadozie ◽  
Anthony Attama

This study seeks to formulate and evaluate a solid lipid nanoparticle-based, solidified micellar carrier system for oral delivery of cefepime. Cefepime has enjoyed a lot of therapeutic usage in the treatment of susceptible bacterial infections; however, its use is limited due to its administration as an injection only with poor patient compliance. Since oral drug administration encourage high patient compliance with resultant effect in improved therapy, cefepime was formulated as solid lipid microparticles for oral delivery using the concept of solidified micellar carrier system. The carrier system was evaluated based on particle yield, particle size and morphology, encapsulation efficiency (EE %), and thermal analysis using differential scanning calorimeter (DSC). Preliminary microbiological studies were done using gram positive and negative bacteria. In vitro release study was performed using biorelevant media, while in vivo release study was performed in white albino rats. The yield of solid lipid microparticles (SLM) ranged from 84.2 – 98.0 %. The SLM were spherical with size ranges of 3.8 ± 1.2 to 42.0 ± 1.4 µm. The EE % calculated ranged from 83.6 – 94.8 %. Thermal analysis showed that SLM was less crystalline with high potential for drug entrapment. Microbial studies showed that cefepime retained its broad spectrum anti-bacterial activity. In vitro release showed sustained release of cefepime from SLM, and in vivo release study showed high concentration of cefepime released in the plasma of study rats. The study showed that smart engineering of solidified micellar carrier system could be used to improve oral delivery of cefepime.


Author(s):  
Nagratna Dhople ◽  
P N Dandag ◽  
A P Gadad ◽  
C K Pandey ◽  
Masthiholimath V S

A gastroretentive sustained release system of itopride hydrochloride was formulated to increase the gastric residence time and modulate its release behavior. Itopride hydrochloride is a prokinetic drug used in the treatment of gastroeosophageal reflux disease, Non-ulcer dyspepsia and as an antiemetic. Hence, itopride hydrochloride beads were prepared by emulsion gelation method by employing low methoxy pectin and sodium alginate as sustained release polymers in three different ratios alone and in combination and sunflower oil was used to enable floating property to the beads. The effect of variation in polymer and their concentration was investigated. The beads were evaluated for production yield, particle size, swelling index, density measurement, buoyancy, drug content, drug entrapment efficiency, in vitro release characteristics and release kinetic study. Based on drug entrapment efficiency, buoyancy, swelling and in vitro release, F9 was selected as the optimized formulation. F9 was further subjected to surface morphology by SEM, in vitro release comparison with marketed formulation, in vivo floating study in rabbits and stability study for 90 days. In vitro release follows zero order and fitted in Korsmeyer peppas model (Non-Fickian release). Therefore, the rate of drug release is due to the combined effect of drug diffusion and polymer swelling. The in vivo X-ray studies revealed that the beads were floating in the rabbit stomach up to 10 hours. Thus, it was concluded that the sustained release formulation containing itopride hydrochloride was found to improve patient compliance, minimize the side effects and decrease the frequency of administration.


2020 ◽  
pp. 1-9
Author(s):  
Yunhong Wang ◽  
Rong Hu ◽  
Yanlei Guo ◽  
Weihan Qin ◽  
Xiaomei Zhang ◽  
...  

OBJECTIVE: In this study we explore the method to prepare tanshinone self-microemulsifying sustained-release microcapsules using tanshinone self-microemulsion as the core material, and chitosan and alginate as capsule materials. METHODS: The optimal preparation technology of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules was determined by using the orthogonal design experiment and single-factor analysis. The drug loading and entrapment rate were used as evaluation indexes to assess the quality of the drug, and the in vitro release rate was used to evaluate the drug release performance. RESULTS: The best technology of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules is as follows: the concentration of alginate is 1.5%, the ratio of tanshinone self-microemulsion volume to alginate volume to chitosan mass is 1:1:0.5 (ml: ml: g), and the best concentration of calcium chloride is 2.0%. To prepare the microcapsules using this technology, the drug loading will be 0.046%, the entrapment rate will be 80.23%, and the 24-hour in vitro cumulative release rate will be 97.4%. CONCLUSION: The release of the microcapsules conforms to the Higuchi equation and the first-order drug release model and has a good sustained-release performance.


1986 ◽  
Vol 12 (14) ◽  
pp. 2521-2540 ◽  
Author(s):  
A. Muktadir ◽  
A. Babar ◽  
A. J. Cutie ◽  
F. M. Plakogiannis

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