Ocular drug delivery systems

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64 Terms

1
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What are ophthalmic drugs?

Drugs that are used for diagnosis and treatment of ocular diseases

2
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What are some examples of ophthalmic products?

Eye drops, lotions, suspensions, ointments, contact lens solutions, ophthalmic inserts

3
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What are some local conditions that may be treated by ocular drug delivery?

Glaucoma, cataract macular degeneration 

4
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What are some systemic conditions that may be treated by ocular drug delivery?

Can arise from diabetes (diabetic retinopathy), hypertension e,g., bleeding, optic neuropathy 

5
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What is the main route of drug delivery for ocular?

Local drug delivery - not a significant portal for systemic

6
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What are the advantages of ocular drug delivery?

Reduces systemic effects and reduces required dosage 

7
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What are some disadvantages of ocular drug delivery?

Patient compliance can be poor and eye can be sensitive to application of medicines

8
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What is the anatomy of the eye?

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9
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What is the choroid in the eye?

Highly vascularised connective tissue that provides a blood supply to the eyeball and contains a viscous vitreous media 

10
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What is an important factor for ocular delivery in relation to the size of the eye?

Size:size/volume ratio of applied dose is key

11
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What is the main pathway for diffusion of drugs into the eye?

Cornea

12
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What are the properties of the cornea?

0.5-0.7mm thick and has 6 different layers, has no blood vessels to nourish it, stratified epithelium 

13
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What is the structure of the cornea?

Epithelium and endothelium rich in lipids, stroma has high water content

<p>Epithelium and endothelium rich in lipids, stroma has high water content</p>
14
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What are the properties of the epithelium in the cornea?

Excludes macromolecules, radius of >1nm, only small drugs of MW of 350 or under/ions can permeate through via paracellular

15
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What type of compounds can pass into the corneal epithelium via the transcellular route?

Lipophilic compounds

16
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What types of molecules does the stroma layer allow into the cornea?

Hydrophilic molecules 

17
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What type of molecules does the stroma limit the penetration of?

Highly Lipophilic (Log P of 2-3) or large MW compounds

18
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What is the corneal endothelium in direct contact with?

Aqueous humour

19
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What impact does the corneal epithelium and the aqueous humour having direct contact have on molecules that can enter?

Resists permeation of Lipophilic compounds 

20
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What is the anterior chamber of the eye?

Space between cornea and eye - containing aqueous humour

21
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What is aqueous humour in the eye?

Watery like liquid inside, made of water and collagen

22
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What is the posterior chamber in the eye?

Between ligaments and lens 

23
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What do the suspensory ligaments do in the eye?

Changes thickness of the eye lens

24
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What happens to suspensory ligaments as you age?

Loses their activity and therefore affects vision

25
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What does the macula lutea do in the eye?

Helps to form the pictures that we see/our vision - links with the optic nerve to send signals to the brain 

26
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What happens if the optic nerve is damaged?

Signals cant be sent to the brain therefore reduces vision

27
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What is an intravitreal delivery as a route of ocular drug administration?

Facilitated by injection e.g., a solution into vitreous humour of the eye between lens and retina

28
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What is the intravitreal route mostly used for?

Anti-VEGF molecules or corticosteroids e.g., dexamethasone 

29
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What is VEGF?

Helps to form blood vessels in the body

30
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Why are anti-VEGF molecules used in the eye?

Reduce amount of VEGF in the eye which can form blood vessels on the macula lutea and affects vision

31
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What is a diagram highlighting different routes of administration into the eye?

knowt flashcard image
32
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What is a Sub-Tenon’s injection?

A local anaesthetic near/beyond the equator performed using a cannula

33
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Why are sub-tenons injections used?

To allow us to Administer medications in posterior segment inflammation 

34
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What drugs are usually used in the eyes a local anaesthetic?

Lidocaine 2% and bupivacaine 0.5% in equal proportion, with/without hyaluronidase 30-150iu/ml - usually a mixture vol of 3-5mL

35
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What is an alternative to lidocaine-bupivacaine mixture?

Articaine - 2%

36
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When are subconjunctival injections used?

Used to deliver anti-infective drugs or corticosteroids for conditions not responding to topical therapy 

37
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Where does the drug diffuse to when injected subconjunctivally?

Anterior and posterior chambers and vitreous humour

38
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What volume of injections are used for subconjunctival injections?

1mL

39
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Why should you take care when injecting drugs subconjunctivally?

blood vessels absorb the drug and ends up in systemic circulation 

40
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What is a diagram showing the tear production system?

Tears produced at rate of 5-9uL in a normal eye - basal tears are continuously secreted by lacrimal glands at average of 0.2

<p>Tears produced at rate of 5-9uL in a normal eye - basal tears are continuously secreted by lacrimal glands at average of 0.2</p>
41
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What do tears contain?

Lysozymes and immunoglobulins which have an anti-infectious activity 

42
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What does the combined mechanisms of lacrimal drainage and blinking mean for ocular administration?

Eye drops are rapidly cleared from conjunctival sac from around 4-23 minutes 

43
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What are the roles of the muscles around the eye?

Change position of the eye 

44
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What is a diagram showing general routes of drug delivery in the eye?

knowt flashcard image
45
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What are some common disorders in the eyes?

Astigmatism, glaucoma, myopia, retinitis pigmentosa, blurred vision, hyperopia, blepharitis, corneal ulcer, photokeratitis, cataracts 

46
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What is glaucoma?

Abnormally high pressure in your eye that can damage the optic nerve 

47
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How does glaucoma develop?

Flow of aqueous humour through the drainage canal, drainage canal becomes blocked and fluid builds up - increased pressure damages blood vessels and the optic nerve

48
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What is open-angle glaucoma?

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49
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What is closed-angle glaucoma?

No gap between lens and iris - aqueous humour builds up in the posterior chambers 

<p>No gap between lens and iris - aqueous humour builds up in the posterior chambers&nbsp;</p>
50
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What are the main aims of pharmaceutical treatments for glaucoma?

Mostly reduce intra-ocular pressure

51
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What are the drug classes for treating glaucoma?

Beta blockers, prostaglandin analogues/prostamides, sympathomimetics, carbonic anhydrase inhibitors and miotics

52
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What are some examples of beta blocker eye drops to treat glaucoma?

Timolol maleate, betaxolol

53
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What are some examples of prostaglandin analogues and prostamide eye drops for glaucoma treatment?

Latanoprost, tafluprost 

54
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What do sympathomimetic eye drops do for treating glaucoma?

Rdeuce aqueous humour formation and increase uveoscleral flow e.g., brimonidine tartrate/apraclonidine

55
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What are carbonic anhydrase inhibitors for treating glaucoma?

Systemic drugs that reduce aqueous humour production - oral or IV administration but only for short term use 

56
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What is an example of a miotic used to treat glaucoma?

Pilocarpine - tablet/eye drops 

57
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What are intra-ocular devices?

Devices inserted into the patients eye and drug is released over a long period of time

58
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What are the advantages of intra-ocular devices?

Release the drug at steady rate, allows accurate dosing, releases drug over a long period of time, reduction in systemic absorption, shows an increase in patient compliance as doesnt need to use an eye drop/ointment daily

59
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What are the disadvantages of intra-ocular devices?

May need to surgically removed the implants, tissue toxicity of polymers which stay inside for a long time, patients may be reluctant to place solid objects in their eyes

60
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What are examples of biodegradable solid devices for in the eye?

PVA, PVP, HPMC, PLGA, PCL

61
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What is an advantage of non-biodegradable solid devices for ocular use?

Better dosing accuracy than soluble ones 

62
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What are non-biodegradable solid devices made from?

Ethylene vinyl acetate copolymers

63
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What is macular oedema?

When fluid and protein deposits collect on/under the macula of the eye and causes it to thicken and swell

64
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