Barriers of Ocular drug delivery system.pptx

In the context of drug delivery, especially with Oral Drug Delivery Systems (ODDs), various barriers can impact the effectiveness and efficiency of drug absorption and therapeutic outcomes. Addressing these barriers through innovative drug delivery systems and formulation strategies can significantly improve the efficacy and safety of oral drug therapies.

1. BARRIERS OF DRUG PERMEATION OF OCCULAR DRUG DELIVERY SYSTEM AL AMEEN COLLEGE OF PHARMACY, BANGALORE PRESENTED BY : Brian. P. Lopes 1 st M. PHARMA Dept of Pharmaceutics Al Ameen college of Pharmacy. Bangalore SUBMITTED TO : Mrs Suma Mam Associate Professor Dept of Pharmaceutics Al Ameen college of Pharmacy. Bangalore

2. CONTENTS Introduction Definition Composition of Eye tear Anatomy of human eye Barriers of drug permeation of Ocular Drug Delivery system a) Anatomical barriers b) Physiological barriers c) Blood-ocular barriers References

3. INTRODUCTION OF OCCULAR DRUG DELIVERY SYSTEM Ocular administration of drug is primarily associated with the need to treat ophthalmic diseases.
Eye is the most easily accessible site for topical administration of a medicine.
Ideal ophthalmic drug delivery must be able to sustain the drug release and to remain in the vicinity of front of the eye for prolong period of time
Several types of the dosage forms can be applied as the delivery systems for the ocular delivery of drugs. In that most prescribed dosage form is the eye drop solution.

4. DEFINATION OF OCCULAR DRUG DELIVERY SYSTEM “These are specialized dosage forms designed to be instilled onto the external surface of the eye (topical), administered inside (intraocular) or adjacent (periocular) to the eye or used in conjunction with an ophthalmic device”. The novel approach of drug delivery system in which drug can instilled on the cull de sac cavity of eye is known has ocular drug delivery system. Cull de sac cavity : the space between eye lids and eye balls.

5. ANATOMY OF HUMAN EYE Layers of Human Eye :- There are three layer of the Eye 1) Sclera – white, outer layer of the eyeball; tough, fibrous membrane that helps to maintain the spherical shape of the eyeball • Cornea – part of sclerotic coat; transparent, front part of eyeball through which light waves pass no blood vessels but lots of nerve endings

6. • Canals of Schlem – venous passages that drain the fluid that accumulates behind the cornea; located where the sclera & cornea meet • Conjunctiva – thin, transparent mucous membrane that covers the eyeball 2) Choroid layer – middle layer of the eye; supplies blood vessels to the eye and contains dark pigment granules that prevent the reflection of light in the eye • Ciliary body – intrinsic muscle; smooth muscle fibers support & modify lens shape • Iris – colored portion of eye formed by circularly and radially arranged smooth muscle fibers; regulates amount of light entering they eye by constricting or dilating the pupil • Pupil – rounded opening of the iris through which light passes 3) Retina – innermost layer of the eye; lines its surface and contains photoreceptors (cells responsible for converting light into nerve impulses – rods & cones)

7. COMPOSITION OF EYE TEAR 1) Water-98%
2) Solid-1.8%
3) Organic element
a) protein -0.67%
b) sugar-0.65%
4) Mineral elements like
a) sodium, potassium and ammonia -0.79%
b) sodium chloride -0.66%

8. BARRIER’S OF OCCULAR DRUG DELIVERY SYSTEM : These barriers can be broadly classified as
a) Anatomical barriers
b) Physiological barriers
c) Blood-ocular barriers

9. a) ANATOMICAL BARRIER : When a dosage form is topically administered there are two routes of entry, either through the cornea or via the non corneal route. CORNEAL CROSS SECTION

10. • The cornea is a very tight multi-layered tissue that is mainly composed of five sections : i ) Epithelium
ii) Bowman’s membrane
iii) Stroma
iv) Descemet’s membrane and
v) Endothelium.

11. i ) Epithelium is the thin outermost layer of fast-growing and easily-regenerated cells. ii) Bowman’s layer consists of irregularly- arranged collagen fibers and protects the corneal stroma. It is 8 to 14 microns thick. iii) Stroma the transparent middle and thickest layer of the cornea is made up of regularly-arranged collagen fibers and keratocytes (specialized cells that secrete the collagen and proteoglycans needed to maintain the clarity and curvature of the cornea) iv) Descemet’s membrane is a thin layer that serves as the modified basement membrane of the corneal endothelium. v) Endothelium is a single layer of cells responsible for maintaining proper fluid balance between the aqueous and corneal stromal compartments keeping the cornea transparent.

12. Out of these it’s the epithelium which acts as the principal barrier.
It acts as a major barrier to hydrophilic drug transport through intercellular spaces.
On the other hand stroma, which consists of multiple layers of hexagonally arranged collagen fibers containing aqueous pores or channels allow hydrophilic drugs to easily pass through but it acts as a significant barrier for lipophilic drugs.
Thus for a drug to have optimum bioavailability, it should have the right balance between lipophilicity and hydrophilicity. The remaining layers are leaky and do not act as significant barriers Non-corneal route by passes the cornea and involves move across conjunctiva and sclera.

13. This route is important especially for large and hydrophilic molecules such as peptides, proteins and si RNA (small or short interfering RNA).
The conjunctiva is more permeable than cornea especially for hydrophilic molecules due to much lower expression of tight junction proteins relative to corneal epithelium.

14. b) PHYSIOLOGICAL BARRIERS The eye’s primary line of defence is its tear film.
Bioavailability of topically administered drugs is further reduced by precorneal factors such as solution drainage, tear dilution, tear turnover, and increased lacrimation. The lacrimal fluid is an isotonic aqueous solution containing a mixture of proteins (such as lysozyme) as well as lipids.

15. It is isotonic aqueous solution containing a mixture of proteins (such as lysozyma ) as well as lipids. Topical application of drug Secretion of Lacrimal fluid Dilution of administered drug. Rapid clearance from precorneal area by lacrimation & through nasolacrimal drainage . Contact time between the tissue & drug molecules reduces Lowers the exact time for absorption & leading to reduced bioavailability.

16. Rapid clearance from the precorneal area by lacrimation and through nasolacrimal drainage and spillage further reduces contact time between the tissue and drug molecules.
This in turn lowers the exact time for absorption leading to reduced bioavailability.
The average tear volume is 7-9 µL with a turnover rate of 16% per minute
Thus drugs administered as eye drops need to be isotonic and non Irritating to prevent significant precorneal loss.

17. c) BLOOD – OCCULAR BARRIERS The blood-ocular barrier normally keeps most drugs out of the eye. However, inflammation breaks down this barrier allowing drugs and large molecules to penetrate into the eye. There are 2 parts in Blood-Retina Barriers : a) Blood-aqueous barrier/ Blood ocular barrier : It is formed by non pigmented ciliary epithelial cells of ciliary body and endothelial cells of blood vessels in iris. Prevent entry of plasma albumin into the aqueous humor and also restrict the hydrophilic drugs to enter the aqueous humor from plasma.

18. b) Blood-retinal barrier/ Blood – posterior barrier : Non-fenestrated capillaries of the retinal circulation and tight-junctions between retinal epithelial cells preventing passage of large molecules from chorio-capillaris into the retina. This prevent drug distribution of drug absorbed by choroid vasculature.

19. 1) https://www.slideshare.net/SakshiMishra70/barriers-of-drug-permeation-in-ocular-drug-delivery-system-241546303 2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874841/ 3) https://nkcf.org/about-keratoconus/how-the-human-eye-works/amp/ REFERENCES

20. THANK YOU 😊