Literature review gel ocular drug delivery systems

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Literature review gel ocular drug delivery systems

Download PDF Abstract Bioassay is defined as estimation or determination of concentration or potency of physical, chemical or biological agents by means of measuring and comparing the magnitude of the response of the test with that of standard over a suitable biological system under standard set of conditions.

Bioassay is a successful tool in estimation and discovery of biologically active substances and important application in sensitivity and specificity of pharmacological applications. Chemical method is very complex method which requires high chemical dosage and chemical composition shows the pharmacological actions against the drug.

Keywords Bioassay, Types of Bioassay, Bioassay for Drugs Introduction Biological assays are methods for the estimation of nature, constitution, or potency of a material by means of the reaction that follows its application to living matter.

Bioassay is defined as estimation or determination of concentration or potency of physical, chemical or biological agents by means of measuring and comparing the magnitude of the response of the test with that of standard over a suitable biological system under standard set of conditions [ 12 ].

An assay is a form of biological experiment; but the interest lies in comparing the potencies of treatments on an agreed scale, instead of in comparing the magnitude of effects of different treatments. Biological assays or biological standardizations or simply bioassays are methods used for estimation of the potency of substances by observing their pharmacological effects on living animals in vivo or isolated tissues in vitro and comparing the effect of these substances of unknown potency to the effect of a standard.

In this analysis the response produced by the test compound is compared with that of standard sample the way similar to other analytical methods but here the biological system is involved in the determination [ 3 ]. Bioassay is Assessment of a biological substance.

Bioassay or biological standardization is a type of scientific experiment typically conducted to measure the effects of a substance on a living organism and is essential in the development of new drugs and in monitoring environmental pollutants [ 4 ].

Bioassays are based upon the use of biological responses as detection system for biologically active substances. In the simplest form it is used to assay the presence and concentration of a particular substance by comparison with a known amount of the same substance.

Both are procedures by which the potency or the nature of a substance is estimated by studying its effects on living matter. Bioassay is a procedure for the determination of the concentration of a particular constitution of a mixture [ 5 - 8 ].

Structure of Biological Assay The typical bioassay involves a stimulus applied to a subject. Application of stimulus is followed by a change in some measurable characteristic of the subject, the magnitude of the change being dependent upon the dose.

The intensity of the stimulus is varied by using the various Doses by the analyst. Principle of Bioassay Active principle to be assayed should show the same measured response in all animal species [ 9 ].

Bioassay involves the comparison of the main pharmacological response of the unknown preparation with that of the standard [ 10 - 14 ].


The method selected should be reliable, sensitive, and reproducible and should minimize errors due to biological variation and methodology. The degree of pharmacological response produced should be reproducible under identical conditions. The reference standard and test sample should have same pharmacological effect and mode of action, so that their DRC curve run parallel and their potency ratio can be calculated [ 15 - 18 ].

Bioassay might measure a diff aspect of the same substance compared to chemical assay. The test solution and standard should be compared for their established pharmacological effect using a specified pharmacological technique [ 20 - 23 ].

Prior to the development of sensitive, precise, accurate chemical and binding displacement assays for the presence or concentrations of drugs or autacoids we had to rely on bio-assays [ 24 - 26 ]. Types of Bioassays There are three main types of bioassays other than qualitative assays [ 27 ] 1.

Indirect Assays based upon quantitative responses 3. Indirect Assay In indirect bio-assays the relationship between the dose and response of each preparation is first ascertained.

Then the dose corresponding to a given response is obtained from the relation for each preparation separately [ 29 ]. These can be biossayed by end point method.

Predetermined response is measured which is produced by threshold effect. Quantal Responses are population response based on an all-or-nothing 0 or 1 — presence or absence response such as death [ 30 - 34 ]. Graded Assay It is proportional to the dose and response may lie between no response and maximum response [ 28 ].

Graded Responses can be any type of measured responses in isolated tissues in particular, but also in whole animals. Such responses are infinitely graded and there are a large number of them.

Examples include contractions of muscle, blood pressure, blood sugar concentrations, etc. This may also limit to analytical dilution assay, as the assay involves the determination of the factor by which the test substance is diluted or concentrated in order to produce response that is equal to that of known amount of the standard drug [ 39 - 40 ].

Its advantage is that it does not depend on the assumption of a dose-response relationship. The main disadvantages are that it is purely subjective, and experimental errors cannot be determined from the assay.

It gives no indication or the parallelism of the dose-response curves of the standard drug and test substance, and hence the qualitative differences, as the effects are matched at only one dose level.

Literature review gel ocular drug delivery systems

Quick and easy; useful when one is has many samples to test and a semiqualitative answer is sufficient.This course concentrates specifically on protein synthesis inhibitors which consist of many different pharmacologic categories with their respective therapeutic agents.

Intracellular protein delivery may provide a safe and non-genome integrated strategy for targeting abnormal or specific cells for applications in cell reprogramming therapy.

Thus, highly efficient intracellular functional protein delivery would be beneficial for protein drug discovery. In this study. The review article aims to highlight the recent developments in various in situ gel-forming polymeric systems that are used to achieve prolonged contact time of drugs with the cornea and increase.

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Topical eye drop is the most convenient and patient compliant route of drug administration, especially for the treatment of anterior segment diseases.

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Principles Involved in Bioassay by different Methods: A Mini-Review | Open Access Journals