Mechanism of action, pharmacological actions, and side effects

Question 1

Beta adrenoceptor antagonists: MOA and PA

Answer 1

MOA: blocks the beta1 adrenoceptor on the ciliary body
(the ciliary body produces the aqueous humor)
Pharm action: reduces the production of aqueous humor, not an effect on accommodation, works equally well in all colored eyes

Question 2

Sympathomimetics- Mydriatics (alpha-2 agonists): MOA and PA

Answer 2

MOA: binds to alpha2 receptors on the ciliary body, binds to the uveosclera
Pharm effect: decrease production of AH, increase outflow through uveosclera

Question 3

Parasympathomimetcs- Miotics: MOA and PA

Answer 3

MOA: agonis at M3 receptor on sphincter muscle and trabecular meshwork
Pharm effect: contraction of the sphincter muscle and trabecular meshwork, increase outflow
(less effective in dark colored eyes)

Question 4

Carbonic Anhydrase (CA) inhibitors: MOA and PA

Answer 4

MOA: inhibition of carbonic anhydrase, this prevents the conversion of CO2 and water to carbonic acid
Pharm effect: decreased CA production will decrease the active transport of Na+ and HCO3; formation of AH depends on Na+ and HCO3 transport

Question 5

Prostaglandin Agonists: MOA and PA

Answer 5

MOA: agonist at the PGF2a receptor causing relaxation on the ciliary muscle
Pharm effect: increases outflow through the uveosclera pathway (anything not going through trabecular mesh work)
Does not affect AH production, may be more effective in hazel/brown colored eyes than blue/green
3-5 weeks to show effect

Question 6

Mast cell stabilizers: MOA and PA

Answer 6

MOA: mast cell stabilizing agent, inhibits irritant receptors and release of sensory peptides from nerves
Pharm effect: prevents release of inflammatory and constricting mediators like histamine, leukotrienes, cytokines, and degradative enzymes from activated mast cells

Question 7

Beta adrenoceptor antagonists: Side effects

Answer 7

Ocular SE: stinging and burning, decreased corneal sensitivity, diplopia(double vision), blurred or cloudy vision, decreased night vision, conjunctival hyperemia(red eyes) and ptosis(droopy eyelids)
Systemic SE:
Cardiac- bradycardia, heart failure and hypotension
Respiratory- bronchospasm in asthamatics
Other: headache, insomnia, taste perversion, depression, impotence

Question 8

Sympathomimetics - Mydriatics(pupil dilates): Side effects

Answer 8

Apraclonidine (not used b/c of hypertension): Ocular- burning and stinging, blurred vision, foreign body sensation, ocular pruritus (itchy eyes)
Systemic- hypotension, oral dryness, ALLERGIC RXN
Brimonidine (primarlly used): oral dryness, foreign body sensation and ocular pruritis
Dipivefrin or Epinephrine: mydriasis, vasoconstriction of the conjunctiva(whitens eyes), burning and stinging, tachycardia, arrhythmias and hypertension, black pigmentation (long-term) of the sclera(white part of eye) and discoloration of contacts (long term epi effect only)
Epinephrine is metabolized by people with brown eyes and is usually used in surgery.
Dipivefrin - lipophilic derivative that is able to get to site of action.

Question 9

Direct acting agents (binding to M3 receptors): Side effects

Answer 9

Ocular: burning and stinging, painful ciliary muscle spasm which can cause temporal or SUPRAOPTIC HEADACHE, blurred vision, myopia (can’t see far), poor vision in dim light, increased visibility of floaters and lacrimation(tears)
Systemic: diarrhea, salivation, sweating, and rhinorrhea

Question 10

Indirect acting drugs(binding to AChE): Side effects

Answer 10

Ophthalmic: burning and stinging, blurred vision, eye pain, lacrimation, headache, BROW ACHE, twitching of the eyelids
Systemic: diarrhea, salivation, sweating, rhinorrhea

Question 11

CA inhibitors: Side effects

Answer 11

Oral: altered taste and smell, dry mouth, excessive thirst, increased urination, systemic acidosis and depression
Ocular: burning or stinging, hypersensitivity(has sulfa in it), headache, bitter, sour or unusual taste, dry eye, foreign body sensation, and blurred vision

Question 12

Prostaglandin Agonists: side effects

Answer 12

Blurred vision, burning and stinging, eye pain, lid edema, and ocular hyperemia, increased brown pigmentation of iris and eyelids, hypertrichosis and hyperpigmentation of lashes, hair growth in other areas, FEW SYSTEMIC SIDE EFFECTS. (side effects are worse in brown eyes)

Question 13

Cannabinoid: side effects

Answer 13

Ocular: conjunctival hyperemia, reduced tear production and miosis
Short term: reduction of systemic blood pressure and tachycardia; psychotropic effects, euphoria or dysphoria, disruption of short term memory, cognitive impairment, sense of time distortion, reduced coordination and sleepiness
Long term: emphysema-like lungs changes and possible increase in lung cancer

Question 14

Mast cell stabilizers: side effects

Answer 14

Cromolyn: burning and stinging, dryness and styes
Nedocromil: headache, burning and stinging, photophobia

Question 15

Sympathomimetics- Mydriatics (alpha and beta agonists): MOA and PA

Answer 15

Dipi and Epi
MOA: binds to alpha 1 and alpha2 receptors and beta 2(ciliary muscle) and beta 1 receptors.
Pharm effect:
alpha 1 - decreases ciliary blood flow, decreases aqueous humor production, contracts the radial muscle in iris to enlarge the pupil.
alpha 2 - decreases production of aqueous humor
beta 2 - causes relaxation of the ciliary muscle and increases outflow
beta 1 - increases aqueous humor production (don’t worry about this effect because it is 3 to 1)
Overall it decreases IOP

Question 16

Indirect Acting Agents: MOA and PA

Answer 16

MOA: inhibits AChE

Pharm effect: more ACh at M3 receptor will increase outflow of aqueous humor