scholarly journals Design and Evaluation of In-Situ Ophthalmic Gel Containing Carbopol and Methylcellulose as Viscosity Modifier

2010 ◽  
Vol 9 (1) ◽  
pp. 17
Author(s):  
Ahmad Zafar ◽  
U. M. Johari ◽  
D. M. Sakarkar
Keyword(s):  
Viscosity Modifier

scholarly journals OPHTHALMIC IN-SITU SUSTAINED GEL OF CIPROFLOXACIN, PREPARATION AND EVALUATION STUDY

2018 ◽  
Vol 10 (4) ◽  
pp. 153 ◽  
Author(s):  
Fadia Yassir Al-bazzaz ◽  
Myasar Al-kotaji
Keyword(s):  
Hydroxypropyl Methylcellulose ◽  
In Vitro Release ◽  
Poloxamer 407 ◽  
Gelling Agent ◽  
In Situ Gel ◽  
Viscosity Modifier ◽  
Vitro Release

Objective: This work aims to formulate and evaluate an ophthalmic in-situ gel of ciprofloxacin hydrochloride (HCl) using poloxamer 407 (P407) as a gelling agent and hydroxypropyl methylcellulose (HPMC) as a viscosity modifier. The objective of this work was to prolong the contact time as the in-situ gel will be converted into a gel upon contact with the cul-de-sac. Methods: Ciprofloxacin HCl ophthalmic in-situ gel was prepared by utilizing (P407) as a temperature-dependent polymer while hydroxypropyl methylcellulose was used as a viscosity modifier. The system was evaluated for physical appearance, pH, drug content, sterility, irritancy and stability. In addition, gelation temperature and a viscosity at different shear rates and different temperatures were studied. The compatibility of the polymer with ciprofloxacin was studied by using fourier transform infrared spectroscopy (FTIR). The in vitro release of the drug was also evaluated and supported by a preliminary in vivo test.Results: The results showed that the prepared formulas were clear, with acceptable pH and the drug contents were within the acceptable limits. FTIR results detected no incompatibility between poloxamer 407 and ciprofloxacin HCl. Notably, the viscosity of the system showed a pseudoplastic behaviour where a reduction in viscosity upon increasing the shear rate was observed. The in vitro release study confirmed the prolongation of the release of the optimized formula (F6) up to 8 h. Upon application of F6 into eyes of rabbits there was no irritancy. In addition, in vivo elimination study showed a prolonged contact for the in-situ gel in comparison with the rapid clearance of eye drop. Stability study indicated the stability of the optimized formula (F6). Conclusion: The prepared optimized formula (F6) represents a successful, safe, stable and prolonged release in-situ gel formula of ciprofloxacin.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Structural Studies on Mitotic Spindle Fibres

1978 ◽  
Vol 36 (3) ◽  
pp. 615-626
Author(s):  
J.R. Mcintosh
Keyword(s):  
Chemical Composition ◽  
Mitotic Spindle ◽  
Structural Studies ◽  
Mitotic Apparatus ◽  
Chemical Studies ◽  
Medical Interest ◽  
Spindle Fibres

The mitotic apparatus is a structure of obvious biological and medical interest, but it has proved to be a difficult cellular machine to understand. The chemical composition of the spindle is only slightly elucidated, largely because of the difficulties in preparing useful isolates of the structure. Chemical studies of the mitotic spindle have been reviewed elsewhere (Mcintosh, 1977), and will not be discussed further here. One would think that structural studies on the mitotic apparatus (MA) in situ would be straightforward, but even with this approach there is some disagreement in the results obtained with various methods and by different investigators. In this paper I will review briefly the approaches which have been used in structural studies of the MA, pointing out the strengths and problems of each approach. I will summarize the principal findings of the different methods, and identify what seem to be fruitful avenues for further work.

Electron Probe Analysis of Muscle

1982 ◽  
Vol 40 ◽  
pp. 398-401
Author(s):  
A. V. Somlyo ◽  
H. Shuman ◽  
A. P. Somlyo
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Resting State ◽  
Binding Sites ◽  
Electron Probe ◽  
Frog Skeletal Muscle ◽  
Electron Probe Analysis ◽  
Probe Analysis

Electron probe analysis of frozen dried cryosections of frog skeletal muscle, rabbit vascular smooth muscle and of isolated, hyperpermeab1 e rabbit cardiac myocytes has been used to determine the composition of the cytoplasm and organelles in the resting state as well as during contraction. The concentration of elements within the organelles reflects the permeabilities of the organelle membranes to the cytoplasmic ions as well as binding sites. The measurements of [Ca] in the sarcoplasmic reticulum (SR) and mitochondria at rest and during contraction, have direct bearing on their role as release and/or storage sites for Ca in situ.

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