Topical Agents

Question 1

Opthalmics Used for Diagnostics: Dilating agents

Answer 1

Sympathomimetic agents: stimulate dilator muscle to induce mydriasis (eg phenylephrine)

Parasympatholytic agents: inhibit Ach receptor interaction in the pupil and ciliary bodies to prevent muscle contraction, inducing mydriasis and cycloplegia (eg atropine, tropicamide, cyclopentolate, scopalamine)

Question 2

Opthalmics used for diagnostics: Fluorescein

Answer 2

dibasic xanthene dye

used to help visualize corneal abrasions, lacerations, and foreign bodies in eye

Question 3

Glaucoma agents: ocular beta-1 blockers

Answer 3

interferes with cAMP-mediated production of aqueous secretions from the ciliary epithelium to reduce IOP
(eg timolol, carteolol, betaxolol)

Question 4

Glaucoma agents: alpha-2 selective agents

Answer 4

reduced production of aqueous humor and increased outflow, to reduce IOP
(eg brimonidine)

Question 5

Glaucoma agents: cholinomimetics

Answer 5

cholinesterase inhibitors: inhibit the enzyme that metabolizes Ach to cause profound miosis and muscle contraction leading to increased outflow to decrease IOP

parasympathomimetics: muscarinic effects, pupillary constriction and increased aqueous humor outflow and reduced outflow resistance to decrease IOP

(eg, carbachol, pilocarpine)

Question 6

Glaucoma agents: diuretics (carbonic anhydrase inhibitors)

Answer 6

slow the formation of bicarbonate ions to reduce Na+ and fluid transport leading to decreased aqueous humor production

(eg, topical dorzolamide and brinzolamide)

Question 7

Prostaglandin agonists

Answer 7

all have slightly different MOA
overall result is increase in aqueous humor outflow

(eg, latanoprost, travoprost, bimatoprost)

Question 8

Opthalmic anti-infectives: quinolones

Answer 8

bactericidal

MOA: inhibit DNA-gyrase in susceptible organisms; inhibits relaxation of supercoiled DNA and promotes breakage of double-stranded DNA so that the MO is unable to reproduce

eg, ofloxacin, ciprofloxacin

Question 9

Opthalmic anti-infectives: aminoglycosides

Answer 9

MOA: bind to 30s and 50s subunits of the ribosome and inhibit bacterial protein synthesis in susceptible organisms, resulting in faulty cell membrane and therefore cell death

eg, gentamicin, tobramycin

Question 10

Opthalmic anti-infectives: sulfonamides

Answer 10

bacteriostatic

MOA: inhibits bacterial folic acid synthesis via competetive antagonism of PABA

eg, sulfacetamide

Question 11

Opthalmics for symptom relief

Answer 11

mast cell stabilizers prevent itching/redness assoc with allergic conjunctivitis (eg, lodoxamide)

certain agents act as mast cell stabilizers AND antihistamines (eg azelastine, olopatadine)

many contain ocular decongestants (eg oxymetazoline, tetrahydrozoline) which act by vasoconstriction (careful- may get rebound ocular congestion if more than 3-4 consecutive days of use

Question 12

Topical corticosteroids

Answer 12

MOA: suppress chemical inflammatory mediator, therefore reversing dilation and vessel permeability

classified as either low, medium, or high potency

high potency topicals can yield systemic effects with prolonged use, esp in children/elderly

Question 13

topical antibiotics

Answer 13

most often for infection prophylaxis in minor cuts, abrasions, burns
systemic rx if no improvement in 3-5 days
most have good gram positive coverage
some used in treatment of acne vulgaris

Question 14

topical antibiotics: mupirocin

Answer 14

used as topical treatment of impetigo
used intranasally for eradication of MRSA colonization
MOA: binds to bacterial isoleucyl transfer-RNA synthetase and thus inhibits protein and RNA synthesis

Question 15

Topical antifungals

Answer 15

Used to treat tinea and susceptible candida species
most work by altering fungal cell permeability
fungistatic, or fungicidal at high concentrations

Question 16

Scabicides/pediculicides: permethrin

Answer 16

treatment of mites and lice

MOA: inhibits sodium ion influx through nerve cell membrane channels in parasites resulting in delayed repolarization and paralysis and death

safest for children, apply head to toe

Question 17

Scabicides/Pediculicides: lindane

Answer 17

MOA: directly absorbed by parasites and ova through the exoskeleton, stimulates organism’s nervous system resulting in seizures/death of parasitic arthropods

not first-line therapy due to adverse effects

serious neurotoxicity/seizures reported with repeated use, rare with one time use

avoid in children/elderly/patients with inflammatory skin conditions

Question 18

Agents for oral candidiasis (thrush): Nystatin

Answer 18

MOA: binds to sterols in fungal membrane, changing the cellular permeability and allowing for leakage of cellular contents

Question 19

Topical agents for herpes labialis (cold sores)

Answer 19

must be used at symptom onset for maximum efficacy
manages symptoms but does not eradicate disease

penciclovir and acyclovir topicals: MOA: converted in vivo to active form that inhibits HSV polymerase, in turn inhibiting herpes viral synthesis and replication

Question 20

topical treatment of vaginal candidiasis

Answer 20

chronic or repeated infections may require systemic rx

eg, miconazole, terconazole, clotrimazole

Question 21

treatment of bacterial vaginosis

Answer 21

often tx’d with po metronidazole

can use vaginal clindamycin cream or metronidazole gel

(can have disulfuram reaction with po or intravaginal metronidazole)