Ocular Pharmacology
Dr. Akhlaque Ahmad, MD
Assistant Professor
Dept. of Pharmacology, ELMC&H Lucknow
Drug delivery in the eye
Topical Intraocular
•Drop Intracameral Intravitreal
•Ointment
•Gel
•Soft contact lens
Periocular
•Subconjunctival
•Subtenon
•Peribulbar Systemic
•Oral
•Retrobulbar
•Intravenous
•Intramuscular
Factors influencing drug absorption in eye
• Drug concentration and solubility:
• Higher the concentration the better the penetration
• Pilocarpine 1-4%
• Viscosity:
• Addition of methylcellulose and polyvinyl alcohol increases drug penetration
• By increasing the contact time with the cornea and altering corneal
epithelium
• Lipid solubility:
• Because of the lipid rich environment of the epithelial cell membranes, the
higher lipid solubility the more the penetration
• Amphipathic : Epithelium
• Lipophilic : Endothelium
• Hydrophilic : Stroma
Eye Drops
• Drop (Gutta)
• Simplest and more convenient
• Mainly for day time use
• 1 drop=50 microlitre
• Conjunctival sac capacity= 7-13 microlitre
• So, even 1 drop is more than enough
Method
•Hold the skin below the lower eye lid
•Pull it forward slightly & instill 1 drop
Eye Drops
Measures to increase drop absorption:
• Wait 5-10 minutes between drops
• Compress lacrimal sac
• Keep lids closed for 5 minutes after instillation
• 50% drug remains 4 min. after instillation
• 10% drug reach aqueous humour
• Compress NLD to decrease systemic absorption
Ointment
• Increases the contact time of ocular medication to
ocular surface thus better effect
• It has the disadvantage of vision blurring
• Drug has to be high lipid soluble with some water
solubility to have the maximum effect as ointment
Ocular devices
• Devices that deliver an adequate supply of
medication at a steady-state level
• Ocusert delivering pilocarpine
• Timoptic XE delivering timolol
• Ganciclovir sustained-release intraocular device
• Collagen shields
Intraocular Drugs
• Antibacterial (antibiotics)
• Antivirals , Antifungals
• Mydriatics and cycloplegics
• Anti-inflammatory agents
• Anti glaucoma drugs
• Ocular Lubricants
Topical Antibiotics
Class Antibiotics Features
Sulfonamides Chlamydial infections like Trachoma
Toxoplasmosis
Cephalosporin Cefazolin, cephalexin H. Influenzae, Enterobacter, Neisseria
Cephalosporin Ceftazidime P. aeruginosa
Cefoperazone
Fluoroquinolones Ciprofloxacin Useful in bacterial conjunctivitis, corneal
ofloxacin ulcer
lomefloxacin
Amino glycosides Gentamycin Mainly against Gram negative bacilli
Tobramycin
Ocular Antiviral agents
Drug Mechanism Uses
Acyclovir Active against HSV I & II,
Inhibits viral DNA HZV
synthesis
Oral, ointment
Trifluridine Block DNA synthesis, Active against HSV I & II
impair RNA replication
Ganciclovir Inhibits viral DNA Active against CMV
synthesis Oral, iv, intravitreal
Ocular Antifungal agents
• Fungal corneal ulcer, Fungal retinitis/Endophthalmitis
• Commonly used drugs are
• Polyenes
• Damage cell membrane of susceptible fungi
• Amphotericin B, Natamycin, nystatin
• Side effect: nephrotoxicity
• Imidazoles
• Increase fungal cell membrane permeability
• Miconazole, ketoconazole, fluconazole
• Flucytocine
• Act by inhibiting DNA synthesis
Mydriatics and Cycloplegics: Anatomy
M3 receptor
α1
Types of mydriatics
Parasympathetic blockage Sympathetic stimulation
Activation of α receptors in radial
Blocking muscarinic receptors
muscles
Relaxing circular muscles Contraction of radial muscles
Passive Mydriasis Active mydriasis
Mydriatics
• Short acting -Tropicamide (4-6 hours)
• Intermediate -Homatropine ( 24 hours)
• Long acting- Atropine (2 weeks)
• Indications
• Corneal ulcer
• Uveitis
• Cycloplegic refraction testing
Miotics
Cholinergic Agonist
Pilocarpine, acetylcholine (miochol),
carbachol (miostat)
Uses:Glaucoma, Uveitis
Mechanisms:
• Miosis by contraction of the iris
sphincter muscle
• Increases aqueous outflow through the
trabecular meshwork by longitudinal
ciliary muscle contraction
• Accommodation by circular ciliary
muscle contraction
Corticosteroids
Side effects of corticosteroids
• OCULAR
• Glaucoma
• Cataract
• Activation of infection
• Delayed wound healing
• SYSTEMIC
• Peptic ulcer
• Hypertension
• Increased blood sugar
• Osteoporosis
• Mental changes
• Activation of tuberculosis and other infections
NSAIDS
• Topical use
• Flurbiprofen
• Indomethacin
• Ketorolac
• Indications
• Episcleritis and scleritis
• Uveitis
• Pre operatively to maintain dilation of the pupil
Ocular Lubricants
Indication
• Ocular irritations in various diseases
• Dry eyes
Ocular anti histaminics
Drugs:
• Olopatadine
• Pheniramine
• Antazoline
• Used in allergic conjunctivitis, irritation,
pinguecula and pterygium
• Can cause sedation, mydriasis and
increase IOP
Local Anesthetic Agents
•Topical
▪Procaine, tetracaine
• Uses: applanation tonometry, gonioscopy, removal of corneal foreign
bodies, removal of sutures, examination of patients who cannot open
eyes because of pain
• Adverse effects: toxic to corneal epithelium, allergic reaction rarely
Ocular Toxicity of Systemic Drugs
Digitalis
Chromatopsia (objects appear yellow) with overdose
Chloroquine
Chloroquine, hydroxychloroquine
• Used in malaria, rheumatoid arthritis, SLE
• Cause vortex keratopathy (corneal verticillata),
usually asymptomatic but can present with glare
and photophobia
• Also cause retinopathy (bull’s eye maculopathy)
Topiramate
• A drug for epilepsy
• Causes acute angle-closure glaucoma (acute eye
pain, redness, blurred vision, haloes)
• Treated by cycloplegics and topical steroids (rather
than iridectomy) with the discontinuation of the drug
Ethambutol
• An anti-TB drug
• Causes a dose-related optic
neuropathy
• Usually reversible but occasionally
permanent visual damage might occur
Sildenafil
• Impairment of colour vision
• Especially blue-green discrimination
• Few cases of sudden loss of vision due
to nonarteritic ischaemic optic
neuropathy (NAION) Nonarteritic anterior ischemic optic neuropathy
(NAION) is the most common form of ischemic
optic neuropathy. It is an idiopathic, ischemic
insult of the optic nerve head characterized by
acute, monocular, painless visual loss with optic
disc swelling.
Thank You!
