1. PHARMACOLOGY OF THE EYE

2. Physiological Anatomy of the Eye

3. Sympathetic Nervous System
mydriasis- contract pupillary dilator muscle (1 receptor)
Relax ciliary muscle for distant vision (ß2 receptors)
Enhance aqueous humor formation (ß2 receptors)
Inhibit aqueous humor formation (2 receptors)

4. Parasympathetic Nervous System Actions
focus eye for near vision (ciliary muscle contraction)
constrict pupil (miosis)-(pupillary sphincter contraction)
Enhance drainage of aqueous humor
All of these effects mediated by muscarinic receptors

5. Drugs promoting mydriasis (pupil dilation)
Sympathomimetics (stimulate or mimic stimulation of sympathetic nerves)
Inhibitors of parasympathetic nervous system (Atropine)

6. Pupillary Muscles

7. Mydriasis

8. Miosis

9. Mydriatics Agents releasing norepinephrine
NICOTINE activates nicotinic receptor (also activates parasympathetics to produce miosis, which is the more common reaction) .
Cocaine increase norepinephrine concentrations of adrenergic receptors
Amphetamine hydroxyamphetamine (0.1% solution) used to diagnose post-ganglionic nerve damage vs. a defect prior to the postganglionic nerve (no reaction means postganglionic nerve defect).
response to amphetamine indicates normal post-ganglionic nerve

10. Alpha1 adrenergic stimulants
PHENYLEPHRINE (mydrifrin) is a drug used in eye drops to dilate pupil
2.5% to 10% solution used to produce mydriasis
Epinephrine (Epitrate) 0.5 to 2% solution to treat glaucoma
increases aqueous humor outflow

11. Muscarinic receptor antagonists
ATROPINE
(Atriposol)- (0.5 to 3% solution) to produce cycloplegia (is paralysis of the ciliary muscle of the eye, resulting in a loss of accommodation.)

12. Drugs producing miosis
Nicotine activates parasympathetic nerves
Muscarinic agonists such as Pilocarpine (Pilocar)
used as 2% solution
acetylcholine (Miochol)

14. Agents preventing acetylcholine degradation
Physostigmine , Ecothiophate (phospholine iodide),
Alpha1 receptor antagonists
Norepinephrine depleting agents- Reserpine (Serpasil)- have the potential of causing ocular side effects (miosis; ptosis)

18. Drugs for Treatment of Glaucoma
ß Blockers
Timolol (Timoptic); Metipranolol (Optipranolol)- they decrease aqueous humor formation
Muscarinic Receptor Agonists-
Pilocarpine (Pilocar)- enhances aqueous humor drainage through canal of Schlemm
Anticholinesterases-
Physostigmine (Isopto eserine), Ecothiophate (Phospholine iodide)- enhances aqueous humor drainage through canal of Schlemm

19. Drugs used to treat ptosis
disruption of sympathetic innervation of superior tarsalis muscle of the eyelid (Horner’s Syndrome)- can reverse with Phenylephrine

20. Routes of Administration
eye drops,
ointments,
injections

22. Eye drops Factors affecting absorption:
1- drug concentration and solubility
(aqueous solution v’s suspension)
2- viscosity (increased residence time)
3- lipid solubility: lipid rich epithelial cell membrane v’s water rich site
4- pH and ionic charge - most eye drops are weak bases existing in both charged and uncharged forms enhancing absorption

23. Eye ointments increases contact time of drug with ocular surface
mixture of petrolatum and mineral oil
water-soluble drugs are insolvent in the ointment and are present as microcrystals. The surface microcrystals dissolve in the tears, the rest are trapped until the ointment melts

24. Eye ointments Only drugs with high lipid solubility and
some water solubility will get into both tears and corneal epithelium
Ex . chloramphenicol and tetracycline both achieve higher aqueous levels as ointment rather than drops

25. Peri-ocular injections
subconjunctival,
allow drugs to bypass the conjunctival/corneal epithelial barrier and reach therapeutic levels in the posterior segment
eg anaesthetic agents, steroids,

26. Intraocular injections
allow instant drug delivery at therapeutic concentrations to target site
Intracameral( within a chamber, such as the anterior or posterior chamber of the eye.EX :an anaesthetic agent into the anterior chamber of the eye, usually during surgery

27. Intravitreal injection
 is an injection into the vitreous, which is the jelly-like substance inside the eye. It is performed to place medicines inside the eye, near the retina. The medicines may help stop growth of new blood vessels.
eg, avastin

28. Systemic drug getting into eye from systemic circulation limited
drugs with higher lipid solubility pass through blood-ocular barrier more readily

29. Systemic
extent of drug bound to plasma proteins also effects access of drug into eye - only unbound form can pass blood-ocular barrier