What is in situ gelling?
In situ gelling systems are polymeric formulations that are in sol forms before entering in the body, but change to gel forms under the physiological conditions. Pectin, xyloglucan, gellan gum, chitosan and alginic acid are some of the natural polymers (1).
Which of the ocular formulation combines the advantages of solutions and gels?
In situ gelation approach combines advantages of both solutions and gels, such as accuracy and ease of administration of the former and prolonged precorneal retention of the latter[7,8]. Sol–gel phase transition on eye surface can be triggered by a change in temperature, pH, or ionic strength.
What is situ gel?
In situ gels are systems which are applied as solutions or suspensions and are capable of undergoing rapid sol-to-gel transformation triggered by external stimulus such as temperature, pH etc. on instillation. The aim of the present study was to formulate and evaluate pH responsive in-situ gel for ophthalmic delivery.
Which solution becomes gel at tear fluid pH?
The 0.4% w/v carbopol/0.5% w/v chitosan based in situ gelling system was in liquid state at room temperature and at the pH formulated (pH 6.0) and underwent rapid transition into the viscous gel phase at the pH of the tear fluid (lacrimal fluid) (pH 7.4).
Why are preservatives not in atropine sulphate eye ointment?
This it because the medicine contains a preservative that can be absorbed by soft contact lenses and cause eye irritation. This eye ointment may cause blurred vision and the pupil(s) may be bigger than normal for a few hours after it is put in, which can make the eyes more sensitive to light.
What is gelling capacity?
Gelling capacity (or water holding capacity) refers to the capability of a hydrocolloid to retain water. Gelling capacity can be defined as the ability of a substance to spontaneously absorb liquids within an aqueous surrounding. More often than not, this term is associated with hydrocolloids.
What is insitu sampling?
Soil moisture can be measured either by using a field soil moisture probe (in situ sampling) or by collecting a soil sample and analyzing it in the laboratory (grab sampling). Another example includes synthetic runoff testing of a wet pond for hydraulic performance using a conservative tracer.
Which of the following is a gelling agent whose gelling ability is pH dependent?
Table 2
| Hydrocolloid as a gelling agent | Characteristics |
|---|---|
| κ-Carrageenan and ί- carrageenan | Thermoreversible gels on cooling |
| Low methoxy pectin | Thermoreversible gels on cooling at acidic pH |
| High methoxy pectin | Thermoirreversible gels on cooling at high acidic pH |
| Gellan gum | Thermoreversible highly transparent gels formed on cooling |
Which of the following is a gelling agent whose gelling ability is pH dependent *?
Chitosan, an amine-polysaccharide is also pH dependent, cationic polymer.
Is atropine and atropine sulfate the same?
Atropine Sulfate Ophthalmic Solution, USP 1%: each mL contains 10 mg of atropine sulfate equivalent to 8.3 mg of atropine.