Ocular Pharm

Question 1

how to calculate eye drop measurements

Answer 1

• expressed as a % solution = parts per 100 i.e. 1% = 1g per 100cc

Question 2

example problem: how many mg of atropine in 5cc of 1% solution?

Answer 2

(1g/100cc) x 5cc = 0.05g = 50mg

Question 3

path of eye drops through the eye

Answer 3

nasolacrimal duct –> mucosa

- no first pass effect through GI or liver

Question 4

when do you use anesthetic eye drops? examples of anesthetic drops?

Answer 4

• ONLY for diagnostic purposes – NEVER give to pts or allow access to pts
• w/ excessive use the eye will literally melt
• tetracaine and proparacaine (better tolerated)

Question 5

epinephrine: uses, effects

Answer 5

• increases trabecular outflow w/ small increase in aqueous production
• causes vasoconstriction, mydriasis
• mostly alpha effects w/ slight beta
• has been used to tx glaucoma but not much anymore

Question 6

phenylephrine

Answer 6

• dilates the eye but doesn’t change your vision much = not much blurring
• direct acting alpha agonist
• alpha-1 selective, little effect on beta
• no effect on ciliary muscle

Question 7

apraclonidine

Answer 7

• alpha agonist (mostly alpha 2)
• lowers IOP by decreasing aqueous production
• does not cross BBB in adults; no effect on BP; almost no cardiac effect
• CAUSES SOMNOLENCE IN KIDS = don’t use for kids

Question 8

what drugs do NOT decrease aqueous production?

Answer 8

prostaglandin analogs

Question 9

brimonidine

Answer 9

• *can cause sedation by stimulating central alpha-2 receptors
• *can’t use in kids b/c of CNS suppression
• decreased aqueous production; increases uveoscleral outflow
• less allergy than apraclonidine
• no effect on heart rate or BP

Question 10

timolol

Answer 10

• nonspecific beta blocker
• decreases aqueous production
• no change in vision, pupil or accommodation
• IOP decrease seen in 30-60 minutes
• less effect at night; taken BID
• s/e: masks hypoglycemic episodes

Question 11

betaxolol

Answer 11

• BETA-1 SELECTIVE beta blocker
• decreases aqueous production by 32-47%
• no effect on outflow or pupil
• less potent than timolol but safer to use in lung disease

Question 12

cholinergic meds

Answer 12

• direct acting = ACh, carbachol, pilocarpine
• indirect = physostigmine, echothiophate
• ACh & carbachol used in cataract surgery
• pilocarpine = increased chance of retinal detachment in contact wearers

Question 13

methacholine

Answer 13

• 2.5% solution used to dx Adie’s tonic pupil
• more resistant to cholinesterase
• can be administered topically

Question 14

pilocarpine

Answer 14

• can cause pupillary block in high concentrations = mechanism for acute angle glaucoma
• induces myopia, increases trabecular outflow and decreases uveoscleral outflow
• would not give if IOP is 40+ b/c of ciliary shutdown; you will make things worse

Question 15

what kind of meds should you not use for sickle cell pts?

Answer 15

• carbonic anhydrase inhibitors (CAIs)

- they will increase the sickling of RBCs

Question 16

1st line drugs for glaucoma? examples

Answer 16

• prostaglandin analogs
• increases uveoscleral outflow but not production
• lowers IOP by 33%
• latanoprost (xalatan), travoprost (travatan), bimotoprost (latisse); all similar efficacies
• latisse also causes increased eyelash growth; can get darkening around eyes/iris

Question 17

s/e of prostaglandin analogs

Answer 17

• hyperemia
• darkening of irides and periorbital skin
• hypertrichosis/eyelash growth (only w/ bimatoprost [latisse])
• reversible CME (cystoid macular edema) = edema in the macula

Question 18

what conditions would you tx w/ corticosteroids?

Answer 18

• uveitis
• corneal edema
• hyperemia
• conjunctivitis
• macular edema

Question 19

contraindications for corticosteroids?

Answer 19

• acute epithelial HSV, fungal eye disease
• after removal of superficial corneal foreign body (prevents healing)
• acute, untreated eye infections = would need antibiotics before every using a steroid

Question 20

example of med NOT to use for contact lens wearers?

Answer 20

• levocabastine

- blocks H1 receptor sites; works in minutes

Question 21

fluoroquinolones

Answer 21

• increases pseudomonas coverage = use for contact lens wearers

Question 22

macrolides

Answer 22

• erythromycin = most commonly used
• azithromycin and clarithromycin also could be used
• not effective v. pseudomonas = NOT for contact lens wearers
• good for tx of blepharitis and bacterial conjunctivitis

Question 23

what would you use to treat endophthalmitis?

Answer 23

• INTRAVITREAL antibiotics

Question 24

what would you see on the cornea to suggest an HSV infection

Answer 24

• dendritic lesion

- would tx w/ trifluridine

Question 25

ocular s/e of systemic meds

Answer 25

• digitalis causes changes in visual perception
• amiodarone = accumulates in cornea; doesn’t affect vision; can cause optic neuropathy
• hydroxychloroquine = bulls eye maculopathy

Question 26

s/e of topamax

Answer 26

• acute myopia
• b/l acute angle closure
• ciliary body swelling and choroidal effusions

Question 27

s/e of sildenafil

Answer 27

• blue haze in vision
• light sensitivity
• pupil sparing CNIII palsy