scholarly journals Ocular in situ gel: An overview

2019 ◽  
Vol 9 (1) ◽  
pp. 337-347 ◽  
Author(s):  
Asmat Majeed ◽  
Nisar Ahmad Khan

Eye is the most sensitive organ of the body. Designing of ocular drug delivery system is the  most challenging field for pharmaceutical scientists as less than 5% of administered drug enters the eye due to the complicated anatomical structure of the eye, small absorptive surface and low transparency of the cornea, lipophilicity of corneal epithelium, pre corneal loss (due to nasolacrimal drainage), bonding of the drug with proteins contained in tear fluid, blinking, low capacity of conjunctival sac, that restricts the entry of drug molecule at the site of action and ultimately leads to poor ocular therapy. To improve ophthalmic drug bioavailability, there are considerable efforts directed towards newer drug delivery systems for ophthalmic administration. These novel drug delivery systems offer manifold advantages over conventional systems as they increase the efficiency of drug delivery by improving the release profile and also reduce drug toxicity. A lot of research going on in this area proves the fact that in situ gelling systems can be beneficial in the ocular drug delivery. In situ gel forming systems are drug delivery systems that are in solution form before administration in the body but once administered, undergo  in situ gelation, to form a gel triggered by external stimulus such as temperature, pH etc.  This review is to Specify a brief summary about in situ gels, various approaches for in situ gelling systems, different types of polymers used in in situ gels, their mechanisms of gel formation and evaluation of polymeric in situ gel. Keywords: in situ gel, polymers, Temperature induced in situ gel system, pH induced in situ gel system, Ion activated systems.

2020 ◽  
Vol 10 (2-s) ◽  
pp. 183-197
Author(s):  
Anjali Sunil Sabale ◽  
Abhijeet D Kulkarni ◽  
Ajay Sunil Sabale

Nasal delivery is an alternative to oral or parenteral administration due to certain limitations such as absorption of the drug, drug targeting to particular organs can cause a problem for administration through oral route.  The nasal route has also been successfully used for bypassing the blood-brain barrier and afterword delivering drug molecules to the central nervous system. Also, lag time related to oral drug delivery is reduces by this route and offers noninvasiveness, self-medication, patient comfort, and patient compliance. Extend drug delivery can be attained by different new dosage forms like in situ gel. In situ formulations are drug delivery systems. The in-situ gelling system is a process in which the solution forms of a gel before administration in the body, but once administrated, it undergoes gelation in-situ, to form a gel. In situ gelling system becomes very popular nowadays because of their several advantages over conventional drug delivery systems like a sustained and prolonged release of a drug, reduced Frequency of administration, improved patient compliance and comfort. Approaches towards the various formulation of in-situ gel concerning temperature, pH, and physicochemical conditions. The in situ gel-forming polymeric formulations offer several advantages like sustained and prolonged action reduced Frequency of administration, in comparison to conventional drug delivery systems.  From a manufacturing point of view, the production of such systems is less complex and thus lowers the investment and manufacturing cost. Various evaluation parameters are considered during the preparation of In-Situ gel. Keywords: Nasal Drug Delivery, In Situ gel, gelation, polymers, etc


Author(s):  
Smriti Sharma ◽  
Vinayak Bhatia

: In this review nanoscale based drug delivery systems particularly in relevance to the antiglaucoma drugs have been discussed. In addition to that, the latest computational/in silico advances in this field are examined in brief. Using nanoscale materials for drug delivery, is an ideal option to target tumours and drug can be released at areas of the body where traditional drugs may fail to act. Nanoparticles, polymeric nanomaterials, single-wall carbon nanotubes (SWCNTs), quantum dots (QDs), liposomes and graphene are the most important nanomaterials used for drug delivery. Ocular drug delivery is one of the most common and difficult tasks faced by pharmaceutical scientists because of many challenges like circumventing the blood–retinal barrier, corneal epithelium and the blood–aqueous barrier. Authors found compelling empirical evidence of scientists relying on in-silico approaches to develop novel drugs and drug delivery systems for treating glaucoma. This review in nanoscale drug delivery systems will help us in understand the existing queries and evidence gaps and will pave way for effective design of novel ocular drug delivery systems


2018 ◽  
Vol 244 (4) ◽  
pp. 283-293 ◽  
Author(s):  
Stephen J. Jones ◽  
Annette F. Taylor ◽  
Paul A Beales

Nanomedicines for controlled drug release provide temporal and spatial regulation of drug bioavailability in the body. The timing of drug release is usually engineered either for slow gradual release over an extended period of time or for rapid release triggered by a specific change in its physicochemical environment. However, between these two extremes, there is the desirable possibility of adaptive nanomedicines that dynamically modulate drug release in tune with its changing environment. Adaptation and response through communication with its environment is a fundamental trait of living systems; therefore, the design of biomimetic nanomedicines through the approaches of bottom-up synthetic biology provides a viable route to this goal. This could enable drug delivery systems to optimize release in synchronicity with the body’s natural biological rhythms and the personalized physiological characteristics of the patient, e.g. their metabolic rate. Living systems achieve this responsiveness through feedback-controlled biochemical processes that regulate their functional outputs. Towards this goal of adaptive drug delivery systems, we review the general benefits of nanomedicine formulations, provide existing examples of experimental nanomedicines that encapsulate the metabolic function of enzymes, and give relevant examples of feedback-controlled chemical systems. These are the underpinning concepts that hold promise to be combined to form novel adaptive release systems. Furthermore, we motivate the advantages of adaptive release through chronobiological examples. By providing a brief review of these topics and an assessment of the state of the art, we aim to provide a useful resource to accelerate developments in this field. Impact statement The timing and rate of release of pharmaceuticals from advanced drug delivery systems is an important property that has received considerable attention in the scientific literature. Broadly, these mostly fall into two classes: controlled release with a prolonged release rate or triggered release where the drug is rapidly released in response to an environmental stimulus. This review aims to highlight the potential for developing adaptive release systems that more subtlety modulate the drug release profile through continuous communication with its environment facilitated through feedback control. By reviewing the key elements of this approach in one place (fundamental principles of nanomedicine, enzymatic nanoreactors for medical therapies and feedback-controlled chemical systems) and providing additional motivating case studies in the context of chronobiology, we hope to inspire innovative development of novel “chrononanomedicines.”


Author(s):  
MRINMOY DEKA ◽  
ABDUL BAQUEE AHMED ◽  
JASHOBIR CHAKRABORTY

Eye is a sensitive organ and is easily injured and infected. Delivery of drugs into eye is complicated due to removal mechanism of precorneal area results decrease in therapeutic response. Conventional ocular delivery systems like solution, suspension, ointment shows some disadvantages such as rapid corneal elimination, repeated instillation of drug and short duration of action. In situ polymeric delivery system will help to achieve optimal concentration of drug at the target site, thereby helps to achieve the desired therapeutic concentration. There are various novel ocular drug delivery systems such as In-situ gel, dendrimers, niosomes, nanoparticulate system, collagen shield, ocular iontophoresis suspension and ocusert etc. In situ gelling systems are liquid upon instillation and undergo a phase transition to form gel due to some stimuli responses such as temperature modulation, change in pH and presence of ions. Various attempts have been made towards the development of stable sustained release in-situ gels. Newer research in ophthalmic drug delivery systems is directed towards an incorporation of several drug delivery technologies, that includes to build up systems which is not only extend the contact time of the vehicle at the ocular surface, but which at the same time slow down the removal of the drug. This is a review based on ocular in situ gels, characteristization, techniques and evaluation of in situ ophthalmic drug delivery systems,


Drug Delivery ◽  
2007 ◽  
Vol 14 (8) ◽  
pp. 507-515 ◽  
Author(s):  
Himanshu Gupta ◽  
Sanyog Jain ◽  
Rashi Mathur ◽  
Pushpa Mishra ◽  
Anil K. Mishra ◽  
...  

2007 ◽  
Vol 83A (3) ◽  
pp. 656-666 ◽  
Author(s):  
H. Ueda ◽  
M.C. Hacker ◽  
A. Haesslein ◽  
S. Jo ◽  
D.M. Ammon ◽  
...  

2018 ◽  
Vol 11 (1) ◽  
pp. 380
Author(s):  
Harsha Vardhani Kondepati ◽  
Girish Pai Kulyadi ◽  
Vamshi Krishna Tippavajhala

2021 ◽  
Vol 14 (11) ◽  
pp. 1201
Author(s):  
Bharti Gupta ◽  
Varsha Mishra ◽  
Sankalp Gharat ◽  
Munira Momin ◽  
Abdelwahab Omri

One of the major impediments to drug development is low aqueous solubility and thus poor bioavailability, which leads to insufficient clinical utility. Around 70–80% of drugs in the discovery pipeline are suffering from poor aqueous solubility and poor bioavailability, which is a major challenge when one has to develop an ocular drug delivery system. The outer lipid layer, pre-corneal, dynamic, and static ocular barriers limit drug availability to the targeted ocular tissues. Biopharmaceutical Classification System (BCS) class II drugs with adequate permeability and limited or no aqueous solubility have been extensively studied for various polymer-based solubility enhancement approaches. The hydrophilic nature of cellulosic polymers and their tunable properties make them the polymers of choice in various solubility-enhancement techniques. This review focuses on various cellulose derivatives, specifically, their role, current status and novel modified cellulosic polymers for enhancing the bioavailability of BCS class II drugs in ocular drug delivery systems.


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