OCULAR DRUGS (Anti-viral,Anti-fungal,Beta blockers in Glaucoma & Prostaglandin Analogs) Flashcards
What is the route of administration for Trifluridine?
Ophthalmic (1% solution)
What is the mechanism of action of Trifluridine?
Fluoro-pyrimidine nucleoside analog
What is Trifluridine the drug of choice for?
Keratoconjunctivitis due to HSV-1 or HSV-2
What limits Trifluridine’s use?
Limited because of topical administration
What is the oral bioavailability of Acyclovir?
20-23%
What is the primary route of excretion for Acyclovir?
Majority excreted unchanged in urine (75%)
What are the mechanisms of resistance for Acyclovir?
Alteration in viral thymidine kinase and DNA polymerase
What are the clinical uses of oral Acyclovir?
First episode genital herpes, recurrent genital herpes, genital herpes suppression in the HIV-infected host, herpes zoster, varicella (age > 2 years)
What are the adverse effects of IV Acyclovir?
Renal insufficiency, CNS toxicity (delirium, confusion), hypersensitivity
What differentiates Valacyclovir from Acyclovir in pharmacokinetics?
Higher bioavailability (~70%) and peak serum acyclovir levels 5-6 times higher with PO valacyclovir
What is the bioavailability of Famciclovir?
~75%
How is Famciclovir converted to its active form?
Rapidly converted to penciclovir by deacetylation of the side chain and oxidation of the prior ring
What are the adverse effects of Famciclovir?
Headache, diarrhea, nausea, rash, neuropathies, hallucinations, or confusional states
What is the mechanism of action of Foscarnet?
Directly inhibits viral DNA and RNA polymerases by interacting with the pyrophosphate binding site
What are the clinical uses of Foscarnet?
CMV retinitis, colitis, esophagitis in immunocompromised patients, acyclovir-resistant HSV infections
What are the major toxicities associated with Foscarnet?
Renal insufficiency, hypokalemia, hypophosphatemia, CNS toxicity, electrolyte imbalance
What is the mechanism of action of Ganciclovir?
Inhibits DNA polymerase of CMV and HSV via phosphorylation by viral thymidine kinase
What are the clinical uses of Ganciclovir?
CMV colitis or esophagitis in HIV patients, CMV retinitis
What is a major side effect of systemic Ganciclovir treatment?
Myelosuppression
What is the prodrug of Ganciclovir?
Valganciclovir
What are the clinical uses of Valganciclovir?
Treatment of CMV infections in immunocompromised patients, CMV retinitis, CMV prophylaxis in transplant patients
What is the mechanism of action of Cidofovir?
Inhibits viral DNA synthesis by slowing and terminating chain elongation; competitive inhibitor with respect to dCTP
What is the primary clinical use of Cidofovir?
Treatment of CMV infections in immunocompromised patients
What is a significant adverse effect of Cidofovir?
Nephrotoxicity
What are the administration routes for Amphotericin B?
Ophthalmic (0.3-0.5% solution), IV (0.5-1 mg/kg), topical, subcutaneous, intrathecal, intralesional injection
How is Amphotericin B excreted?
Renal excretion (4%) and biliary excretion
What is the mechanism of action of Amphotericin B?
Binds to ergosterol in fungal cell membranes, forming cytotoxic ‘leaky pores,’ causing loss of intracellular contents
What is the resistance mechanism of Amphotericin B?
Decreased permeability or modification of ergosterol concentration at the sterol binding site
What is the spectrum of activity of Amphotericin B?
Candida spp, Cryptococcus neoformans, Aspergillus spp, Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis, systemic infections, fungal meningitis
What are the major side effects of Amphotericin B?
Nephrotoxicity, infusion reactions, anemia, and electrolyte imbalances (hypokalemia, hypomagnesemia)
What is the route of administration for Natamycin?
5% topical suspension
What is the mechanism of action of Natamycin?
Inhibits fungal growth by binding to ergosterol, preventing membrane formation and function
What are the clinical uses of Natamycin?
Yeast and fungal keratitis, conjunctivitis
What is the bioavailability of Fluconazole?
High bioavailability
How is Fluconazole excreted?
Unchanged in urine
What is the mechanism of action of Fluconazole?
Inhibits fungal P450-dependent enzymes, blocking ergosterol synthesis
What are the primary clinical uses of Fluconazole?
Oropharyngeal candidiasis, esophageal candidiasis, vaginal candidiasis, cryptococcal meningitis
What is the resistance mechanism of Fluconazole?
Can occur with long-term use, especially with prophylactic use
What are the adverse effects of Fluconazole?
Nausea, headache, abdominal pain, and elevated liver enzymes
How does Itraconazole absorption improve?
Improved with food due to decreased gastric pH
Does Itraconazole cross the BBB?
No, CSF: serum concentration ratio is <0.01
What is the mechanism of action of Itraconazole?
Inhibits fungal P450-dependent enzymes, blocking ergosterol synthesis
What are the clinical uses of Itraconazole?
Dermatophytoses, endemic mycoses (Histoplasma, Blastomyces, Sporothrix), aspergillosis, and yeast keratitis
What are the side effects of Itraconazole?
GI upset, hepatotoxicity, and risk of drug interactions (CYP3A4 inhibitor)
How is Ketoconazole excreted?
Parent drug and metabolites excreted in feces and urine
Does Ketoconazole cross the BBB?
No, CSF: serum concentration ratio is <0.1
What is the mechanism of action of Ketoconazole?
Inhibits fungal P450-dependent enzymes, blocking ergosterol synthesis
What are the clinical uses of Ketoconazole?
Non-meningeal cryptococcosis, mucocutaneous candidiasis, seborrheic dermatitis, and pityriasis versicolor
What are the adverse effects of Ketoconazole?
Hepatotoxicity, nausea, and inhibition of steroid synthesis
What are the routes of administration for Miconazole?
Topical (2% solution or ointment), intravaginal suppository (20 mg/g), IV injection
What is the mechanism of action of Miconazole?
Inhibits fungal ergosterol synthesis
What are the clinical uses of Miconazole?
Vulvovaginal candidiasis, dermatophytic infections (tinea cruris, tinea pedis), yeast keratitis
What are the side effects of Miconazole?
Rare but may include local irritation or hypersensitivity
What is the clinical use of Timolol?
Treatment of glaucoma and ocular hypertension
What are the side effects of Timolol?
Localized irritation and burning, CNS effects (lethargy, lightheadedness, fatigue, memory loss), CV effects (bradycardia, hypotension, syncope, arrhythmias, bronchoconstriction, pulmonary edema, CHF, and death)
What makes Levobunolol different from Timolol?
It is less expensive than Timolol
What are the side effects of Levobunolol?
Localized irritation and burning, CNS effects (lethargy, lightheadedness, fatigue, memory loss), CV effects (bradycardia, hypotension, syncope, arrhythmias, bronchoconstriction, pulmonary edema, CHF, and death)
What is a key benefit of Betaxolol compared to other beta blockers?
Useful in patients with CHF, asthma, or conditions where β1 blockade is contraindicated due to cardioselectivity
What are the clinical uses of Carteolol and Metipranolol?
Treatment of ocular hypertension and glaucoma
What are the side effects of Carteolol and Metipranolol?
Localized irritation and burning, CNS effects (lethargy, lightheadedness, fatigue, memory loss), CV effects (bradycardia, hypotension, syncope, arrhythmias, bronchoconstriction, pulmonary edema, CHF, and death)
What is the mechanism of action of Latanoprost?
Increases uveoscleral aqueous outflow as an ester prodrug of PGF2α
What are the clinical uses of Latanoprost?
Treatment of open-angle glaucoma
What are the side effects of Latanoprost?
Burning, stinging, conjunctival hyperemia, foreign body sensation, blurred vision, and increased pigmentation of the iris (especially in green-brown, yellow-brown, and blue-gray-brown eyes after prolonged use)
What is the half-life of Latanoprost?
17 minutes
What is the mechanism of action of Bimatoprost?
Increases uveoscleral aqueous outflow as a prostaglandin analog
What are the clinical uses of Bimatoprost?
Treatment of open-angle glaucoma
What are the side effects of Bimatoprost?
Burning, stinging, conjunctival hyperemia, foreign body sensation, and blurred vision
What is the onset of action for Travoprost?
2 hours
What is the mechanism of action of Travoprost?
Increases uveoscleral aqueous outflow as a prostaglandin analog
What are the side effects of Travoprost?
Burning, stinging, conjunctival hyperemia, foreign body sensation, and blurred vision
What is the onset of action for Unoprostone?
30 minutes
What is the mechanism of action of Unoprostone?
Increases uveoscleral aqueous outflow as a docosanoid compound related to a PGF2α metabolite
What are the side effects of Unoprostone?
Burning, stinging, conjunctival hyperemia, foreign body sensation, and blurred vision
What is the duration of action for Latanoprost, Bimatoprost, and Travoprost?
24 hours
What is the clinical use of Unoprostone?
Treatment of open-angle glaucoma