Lec.10: Prostaglandin Analogs Flashcards
list the common prostaglandin drugs.
latanoprost, travoprost, bimatoprost and tafluprost
what enzymes are crucial to converting prostaglandins from their prodrug form?
esterases
once prostaglandins are activated by the body, what receptors do they act on?
F2alpha receptors on ciliary body
name the ester prodrugs.
latanoprost, travoprost and unoprostone
what type of prostaglandin is bimatoprost considered?
prostamide (nitrogen attached to carbonyl group)
what is the mechanism of action for prostaglandin drugs?
increase outflow through uveoscleral pathway
what class of glaucoma drugs are considered to by first line therapy?
prostaglandins
what are the indications for prostaglandins?
POAG, NTG, PDS, XF and chronic angle closure glaucoma
what are the contraindications for PGs?
uveitic glaucoma (inflammation), pediatric glaucoma, allergy to drug and pregnancy
which PG analog has an association to cystoid macular edema?
latanoprost
how long prior to surgery should PG medication be discontinued?
1 month
what is the best time for patients to take PG medication?
evening
what are the side effects of PG medications?
conjunctival hyperemia, iris color change, eyelash change, skin pigmentation and deepening of upper eye lid sulcus
list the drugs in order of severity of conjunctival hyperemia?
brimatoprost>travoprost>latanoprost
what percentage of PG users develop some sort of iris color change?
30-40%
what is the reason for a change in iris color?
increase in melanin content (permanent change)
what is a side-effect of excess drops around the eyelash and adnexa area?
increase in eyelash length and skin pigment change
how long should patient keep their eyes closed when a PG drop is applied?
5 minutes
how long should drops be spaced apart?
15 minutes
what popular preservative may be linked to CME (cystoid macular edema)?
benzalkonium chloride (BAK)
in general why do PG’s have low systemic side effects?
half-life of only 17 minutes in human plasma
what preservative will form a precipitate when mixed with latanoprost?
thimerasol (found in CL solution)
how much does latanoprost reduce mean diurnal IOP?
32%
are PG’s better than timolol in african americans?
yes
why are PG’s not as effective in patients with pigment?
drug is absorbed by pigment and not distributed to the aq humor as effectively
what is the additional drop in IOP if a beta blocker is prescribed alongside latanoprost?
14%
how do cholinergic agonist like pilocarpine act?
act by increasing trabecular outflow facility
is adding pilocarpine to PG a good idea?
no
according to the FDA what is the problem with combination of PG’s?
they must produce an additional IOP decrease of 20%
is unoprostone a PG?
no (but it once was considered to be)
how does unoprostone work?
works more on the trabecular outflow than the uveoscleral outflow
