This document provides an overview of ocular pharmacology. It discusses key concepts such as bioavailability, compartments, and tissue binding. It describes relevant anatomic characteristics of the eye like the cornea and sclera barriers. Various vehicles for drug administration are outlined including eyedrops, ointments, gels, and injections. Common drug families are then reviewed such as anesthetics, sympathomimetics, anticholinergics, anti-inflammatories, and antiglaucoma medications. Side effects and comparisons of major drugs are also summarized.

1. Ocular pharmacology
.Mohammed A. Almasswary, MBBS, FRCSC
Cornea & Refractive Surgeon
College of Medicine
King Khalid University

2. Bioavailability-% of unchanged drug delivered to site of potential action ( 1
regardless of route of administration
It is a % of availability medication that end in the target organ or structure or
target function
You must have drug which have very good bioavailability it will has available
and target a maximum concentration or function
Compartment-body space in which drug is homogeneously distributed( 2
it is a target structer or target cell
It will target a specific structer but some time target another structer
Tissue binding-makes drug unavailable for elimination and prolongs its( 3
retention in a compartment

3. Relevant anatomic characteristics of the eye
Cornea-functions as a permeability barrier(natural barrier( (does not allow 1)
(drugs to cross by simple diffusion
Some time it is not very good ,it is facet to penetrate intra ocular sturacter by our
medication
You must have medication that easy penetrate without affect integrety of eye
Properties of different corneal layers
Epithelium- hydrophobic
Stroma- hydrophilic
Endothelium- hydrophobic
you must have medication over come this barrier
‫ اللي موجود بحيث يكون الدواء‬duble barrier ‫لزم نجيب دواء يستطسع ان يخترق القرنيه ويتجاوز‬
‫ بالتالي يستطيع ان يخترق القرنيه‬hydrophobic, hydrophilic
For maximal corneal drug penetration a molecule must have optimum
ratio of hydro- and lipo- philicity

4. Sclera-(another barrier(due to intraocular pressure there is( 2
typically a constant outward flow across the sclera, therefore
even sub-Tenon’s injections penetrate the globe slowly
There is inactive pump or inactive process of diffusion of fluid from
eye itself into sub tenon or sub connective space due to IOP
the fluid moving
Blood ocular barrier-present due to tight junctions of non( 3
pigmented ciliary epithelium, retinal pigment epithelium, and
retinal capillary endothelial Cells
Present at level of small capillary at the CB , iris, small capillary in
retina
There is absolute barrier at this level

5. Vehicles of drug administration
(Eyedrops-major route of ocular drug administration(common way )1
Drops are advantageous because they avoid systemic toxicity
Advantage: put drop dirct on eye it self
Disadvantage: fast flash out by tearing, exposure very limit, drop not act for long
time
problems- short duration of availability in the tear film and need to
pass through a barrier with limited permeability
tear volume=7ul expanded to 30-50 ul by most commercial eye drops
max. bioavailability is afforded by a drop size of 20 ul
:For example
you replace your tear film this tear volume can ‫دمعه النسان حجمها 7-01 كل 5 دقائق تقريبا‬
? expand 20-25ul if excess become epiphora why mention this
If you take any eye drop the volume from 20-25 some time 50ul the eye take 40%
of total
‫بعض المرضى يقول احط القطره وتخرج برى‬
Volume excess capacity of eye then go out

6. -tear turnover
nonirritated eye-15%/min-
following 1 drop-30%/min-
drops therefore wash out in about 5 min, optimum time-
between drops is 5 min
of drop egresses through tear duct not into eye 80%
?How improve function of drops
Add some thing to facilitate the quick penetration
Factors affecting availability of topical meds
Surfactants-increase solubility of hydrophilic drugs by altering. 1
permeability of epithelial membranes
Drug concentration-concentrated solutions are used to. 2
maximize the amount of drug entering the eye during the
limited availability provided by a drop
‫عشان كذا الطبيب يقول رج القطره قبل ما تستخدمها‬
Viscosity-high viscosity solutions increase drug contact time. 3
on the cornea
‫عشان نعرض العين لوطول وقت ممكن للدواء‬

7. Ointments )2
a( Advantages
(Increase drug contact time (very long time of exposure
b( Disadvantages
May act as a barrier to vision and penetration of other drops . 1
Slow release of some meds from ointment may result in subtherapeutic levels of drug . 2
‫اذا الواحد يبغى يروح العمل شكلها مو وطبيعي وتاثر على الرؤيه‬
High bind feature, not fast release as compers to drops
)-Gel-made of high viscosity acrylics (ex. Ocuserts ) 3
slowly releases drug at a steady state level at overall lower conc. and less systemic side-effects
Small reservoir smellier to contact lens field by medication insertion in upper fornix put up to 2-3 weeks some
time 1 month, put in eye then slow release of drug
Drug soaked soft CLs/collagen shields-also provide prolonged drug )4
(contact time (rate of drug release may not be constant
Subconjunctival/ retrobulbar injection (sub tenon)-allows drug to bypass conj/corneal )5
epithelial barriers, can allow meds to reach therapeutic levels behind the
lens/iris diaphragm
Intraocular injection : inject inside the eye it self can inject in anterior chumper or in vitrouse ) 6
Systemic administration: oral , IM , IV )7

8. Drug families
)Anesthetics (topical and local
,general mechanism-reversible block of conduction through nerve fibers
Use in surgery some time in examenation
toxicity- dose related
,injected agents-typically tremor which proceeds to seizure
cardiovascular instability and arrhythmia, respiratory depression
Use in surgery s.e it go to systemic
topical agents-increased corneal epithelial permeability, altered corneal
(metabolism with decreased wound repair (common use in clinic
additives for regional blockade
a(epinephrine (1:100,000-1:200,000(-causes vasoconstriction to
prolong duration of action and provides hemostasis
b(hyaluronidase-increases tissue permeability to injection
topical agents
a(proparacaine-OPHTHETIC-0.5% ester solution, onset 15 sec, lasts 20
min, good for culture corneal ulcer because not bacteriostatic
b(benoxinate-in FLURESS-0.4% solution, similar to proparacaine
.c(tetracaine-0.5% ester solution, longer duration than above
.d(cocaine-1-4%

9. Sympathomimetic agents
symathetic fibers innervate dilator muscle dilate of pupil
Do vasoconectraction in systemic and dilation in pupil
this medication very useful in examenation like fundus
.epinephrie, vasoconstriction, pupil DILATION. It does not cause cycloplegia
It is given with local anesthetic inj. To prolong the action of the local
.Phenylephrine, dilates the pupil, no cycloplegia. Dilation lasts for 3-4 hrs
(Cocaine, prevents re uptake of nor epinephrine thus causing pupil dilation.(rare use
This group of medication just dilate the pupil NOT affect in CB Not do cycloplegia = paralysis of CB
It is short action about 3-4 hours

10. Anticholinergic drugs
Indirect way that stimulation the sympathetic similar to sympathatomimic
.blocks acetylcholine action
.Atropine, cycloplegia and mydriatic. Lasts 10 days
.Homatropine, 2-4 days
.Cyclopentolate, 24hrs
This medication do dilated of pupil and DO cycloplegia
:So, this medication do
Mydriasis
Loss of accommodation
This medication Not use for examination in clinic it is use for theraputic

11. comparison of actions of major cycloplegics
mydriasis cycloplegia duration
Atropine 30 min 1 hr 14 days
homatropine 10-30 min 30-90 min 6hr-4 days
scopolamine 40 min 40 min 24 hr
cyclopentolate 15-30 min 15-45 min 24 hr
tropicamide 20-30 min 20-25 min 4-6 hr
Tropicamide shortest>>> use in surgery like glucoma surgery

12. Systemic side effect
stress ‫تذكروا ايش يصير لك وقت التختبار مع‬
dry mucus membrane
urinary retention
tachycardia
Confusion especially in children
‫فلزم تنبهين اهله‬

13. Cholinergic drugs
Rare use in clinic use in glucoma
causes pupillary constriction
acetylcholine, used in surgery
.carbachole, pilocarpine. Both are used in glaucoma management
.Side effects: salivation, diarrhea, nausea. Bronchial spasm

14. Anti inflammatory drugs
Steroids,(common use( suppress inflammatory cells and stabilizes intracellular and
.lysosomal membranes
Most of it use topical some time use injected like in diabetic reitnopathy some time use
oral like optic neuritis
Cortisone
prednisone
dexamethasone
Fluromethilone

15. Antihistamines mainly in allergy
”Livostin, “levocabastine
cromolyn Na. mast cell stabilirization
”Alomide “lodoxamide tromethamide
NSAID patents cant use steroid use it like glucoma the steroid increase glucoma
inhibits cyclo-oxygenase reducing production of prostaglandins
”fluriprofen “ocufen
”diclofenac “voltaren
”ketorolac “acular

16. Topical anti infections agents
.Antibacterial
Antiviral , e.g. acyclovir , trifluridine, idoxuridine
)Acyclovir common use not drop it is onitment other name (zophirax or zophyrax
‫ماني متاكده من السبلنق‬
antifungal, e.g. amphotericin B, natamycin, fluconazole
Not drops , not use topical

17. Antiglaucoma drugs
Either increase daring or decrease production
;Beta blockers.1
. decreases aqueous production. No effect on the pupil
)timolole,(common
”betoxolole “betoptic
”Levobunalole “levobunalole
Contraindications
asthma, pulmonary disease, heart failure,
.arrhythmias
;Side effects
.local: redness, SPK, burning

18. Parasympathomimetics. 2
Increase outflow this not good in ACG becz the angle close not driange
.pilocarpine, carbachole
.Increase aqueous outflow
Alpha agonists use in past not now . 3
”epinephrine, dipinephrine “propine
.it acts by decreasing aqueous production and increasing outflow
Aproclonidine “iopidine”hyperemic and recurrent inflammation this drug now not
use
Brimonidine “Alphagan”, both act by decreasing aqueous production ,

19. prostaglandin analogs act mainly by increase outflow .4
.Latanoprost “Xalatan”. It increases outflow
.Very effective in lowering IOP
.Problems: very expensive, hyperpigmentation of iris , uveitis
Increase eye lashes
Carbonic anhydrase inhibitors topical , oral , IV. 5
”dorzolamide “Trusopt

20. ‫اهم سليد‬
Ocular toxicity form
Toxic optic neuropathy becz direct toxic to optic nerve may lead to blidness
ethambutole
isoniazide
methanole
Sulfonamide
Toxic cataract
Steroids common one also produce glucoma
long acting miotics
anticholestrole agents
Corneal keratopathy
Chloroquine anti malaria and use in RA
Tamoxifen use in Brest cancer
Amiodarone cardiac medication

21. Chloroquine/ Hydroxychloroquine
used for treatment of malaria, rheumatoid arthritis, SLE, sarcoid( 1
bind to melanin, build up in RPE leads to toxicity affect retina and lead to blidness( 2
effects are dose dependant-hydroxychloroquine 400 mg/day or less generally( 3
safe
(toxic effects (>100 grams total chloroquine dose( 4
(retinopathy (bull’s eye-
More use >>>> toxic affect

22. ‫‪The End‬‬
‫بالتوفيق‬