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OPHTHALMOLOGY > OCULAR DRUGS (Ocular routes & Antibacterial) > Flashcards

OCULAR DRUGS (Ocular routes & Antibacterial) Flashcards

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1
Q

What is the absorption pattern of topical (eye drops or ointment) administration?

A

Through the conjunctiva, the absorption is rapid/prompt, depending on formulation.

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2
Q

What are the special utilities of topical administration (eye drops or ointment)?

A

Convenient, economical, relatively safe.

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3
Q

What are the limitations and precautions of topical administration (eye drops or ointment)?

A

Compliance, corneal and conjunctival toxicity, nasal mucosal toxicity, systemic side effects from nasolacrimal absorption. The patient should close the eye for at least 5 minutes after instilling the eyedrops to prevent systemic absorption.

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4
Q

What is the pathway of eyedrops after instillation?

A

The eyedrops pass through the canaliculus, nasolacrimal sac, nasolacrimal duct, the nose, and then are swallowed. They are very concentrated drugs that can cause systemic side effects when absorbed.

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5
Q

What is the absorption pattern of subconjunctival, Sub-Tenon’s, or retrobulbar injections?

A

Prompt or sustained, depending on formulation.

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6
Q

What are the special utilities of subconjunctival, Sub-Tenon’s, or retrobulbar injections?

A

Anterior segment infections, posterior uveitis, cystoid macular edema.

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7
Q

What are the limitations and precautions of subconjunctival, Sub-Tenon’s, or retrobulbar injections?

A

Local toxicity, tissue injury, globe perforation, optic nerve trauma, central retinal artery and/or vein occlusion, direct retinal drug toxicity with inadvertent globe perforation, ocular muscle trauma, prolonged drug effect.

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8
Q

What is intracameral administration?

A

Injection of the drug into the anterior chamber of the eye.

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9
Q

What is the absorption pattern of intracameral injections?

A

Prompt.

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10
Q

What are the special utilities of intracameral injections?

A

Anterior segment surgery, infections.

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11
Q

What are the limitations and precautions of intracameral injections?

A

Corneal toxicity, intraocular toxicity, relatively short duration of action. Toxicity is the primary limitation.

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12
Q

What is the absorption pattern of intravitreal injection or device administration?

A

Absorption is circumvented; it has an immediate or local effect, with potential for a sustained effect.

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13
Q

What are the special utilities of intravitreal injection or device administration?

A

The drug is administered directly to the site of action. Used for endophthalmitis, retinitis, and age-related macular degeneration.

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14
Q

What are the limitations and precautions of intravitreal injection or device administration?

A

Renal toxicity, degenerations in the macula.

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15
Q

What is the absorption pattern of Azithromycin?

A

Topical 1% solution or oral (PO) with enteric-coated tablets or acid-resistant salts since it is inactivated by acid.

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16
Q

How is Azithromycin distributed in the body?

A

Distributes to most body compartments, only crossing inflamed meninges.

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17
Q

What is the half-life (t1/2) of Azithromycin?

A

68 hours.

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18
Q

How is Azithromycin excreted?

A

Released into bile and feces as an active drug, making it effective for biliary infections.

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19
Q

What is the mechanism of action of Azithromycin?

A

Bacteriostatic; reversibly binds to the 50S ribosomal subunit and blocks protein synthesis.

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20
Q

What is the resistance mechanism against Azithromycin?

A

Resistance develops mostly from mutations in the binding site on the 50S ribosomal subunit.

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21
Q

What is the spectrum of activity and clinical uses of Azithromycin?

A

Same as erythromycin plus H. influenzae, Moraxella, and Chlamydia. Used for community-acquired pneumonia, pertussis, Corynebacterium infections, and conjunctivitis.

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22
Q

What is unique about Azithromycin’s pharmacokinetics in infections?

A

Taken up by phagocytes and transported to the site of infection, allowing for 24-hour dosing in a 5-day cycle.

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23
Q

What are the drawbacks and side effects of Azithromycin?

A

GI upset, abdominal cramping, gas, diarrhea, rare intestinal superinfections, cholestatic hepatitis with estolate salts, QT elongation, and hypersensitivity reactions.

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24
Q

Does Azithromycin inhibit cytochrome P450 enzymes?

A

No, it does not inhibit cytochrome P450 enzymes, but it interacts with the cytochrome P450 system, potentially causing drug interactions (e.g., with theophylline and carbamazepine).

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25
What is the most significant side effect of Azithromycin when used topically?
Hypersensitivity reactions.
26
What is the absorption pattern of Bacitracin?
Administered topically as a 500 units/g ointment. A small absorbed amount is excreted in urine.
27
What is the mechanism of action of Bacitracin?
Produced by Tracy-I of Bacillus subtilis; interferes with the late stage of bacterial cell wall synthesis.
28
What is the spectrum of activity of Bacitracin?
Active against G+ cocci and bacilli, Neisseria, H. influenza, Treponema pallidum, Actinomyces, and Fusobacterium.
29
What are the clinical uses of Bacitracin?
Used for suppression of flora in surface abrasions or wounds, conjunctivitis, blepharitis, keratitis, keratoconjunctivitis, corneal ulcers, blepharoconjunctivitis, meibomianitis, and dacryocystitis.
30
What are the drawbacks and side effects of Bacitracin?
Nephrotoxic (only used topically) and hypersensitivity reactions.
31
What are the routes of administration for Chloramphenicol?
Topical 1% ointment or drops, PO (well-absorbed), IV, IM.
32
What is the oral availability of Chloramphenicol?
0.8
33
What is the half-life (t1/2) of Chloramphenicol?
2.5 hours.
34
What is the volume of distribution (Vd) of Chloramphenicol?
66 L/70 kg.
35
What is the mechanism of action of Chloramphenicol?
Bacteriostatic; bactericidal for H. influenzae. Binds reversibly to a receptor and inhibits activity of bacterial 50S ribosomal subunit.
36
What is the resistance mechanism for Chloramphenicol?
Resistance occurs via enzymatic inactivation, but this does not happen in Rickettsia species.
37
What are the clinical uses of Chloramphenicol?
Broad spectrum for G+ and G-. First choice for H. influenzae in children, conjunctivitis, and keratitis.
38
What are the major drawbacks and side effects of Chloramphenicol?
Bone marrow suppression (reversible/irreversible), gray baby syndrome, dose-related anemia, hypersensitivity, and toxicity to neonates.
39
What is a way to prevent systemic absorption of Chloramphenicol during topical use?
Press on the lacrimal sac for at least 5 minutes.
40
What is the absorption pattern of Erythromycin?
Topical 0.5% ointment, PO (requires enteric-coated tablets or acid-resistant salts), IV.
41
What is the oral availability of Erythromycin?
0.35
42
What is the mechanism of action of Erythromycin?
Bacteriostatic; reversibly binds to the 50S ribosomal subunit and blocks protein synthesis.
43
What are the resistance mechanisms for Erythromycin?
Mutations in the 50S ribosomal subunit binding site.
44
What is the spectrum of activity of Erythromycin?
G+ organisms, Mycoplasma pneumoniae, Chlamydia (safe for pregnant women), Legionella pneumoniae, Campylobacter jejuni.
45
What are the clinical uses of Erythromycin?
Community-acquired pneumonia, pertussis, superficial ocular infections, and prophylaxis of ophthalmia neonatorum.
46
What are the side effects of Erythromycin?
GI upset, abdominal cramping, QT elongation, hepatotoxicity, CYP450 inhibition, and hypersensitivity.
47
What is the mechanism of action of Gentamicin Sulfate?
Inhibits bacterial protein synthesis by binding to 30S ribosomes; bactericidal.
48
What is the spectrum of activity of Gentamicin?
Broad spectrum, except for streptococci and anaerobic bacteria.
49
What are the clinical uses of Gentamicin?
Conjunctivitis, keratitis, corneal ulcers, dacryocystitis, and superficial infections.
50
What are the drawbacks of Gentamicin?
Hypersensitivity and toxicity concerns.
51
What is the absorption pattern of Tobramycin?
Topical 0.3% solution or ointment, IM, and IV (good absorption).
52
What is the mechanism of action of Tobramycin?
Bactericidal; binds to the 30S ribosomal subunit, causing abnormal peptide synthesis. Synergistic with β-lactams.
53
What is the spectrum of activity of Tobramycin?
Aerobic G- rods, H. influenzae, M. catarrhalis, Shigella species, and limited activity against facultative anaerobes.
54
What are the clinical uses of Tobramycin?
External infections of the eye, adnexa, and superficial infections.
55
What are the drawbacks and side effects of Tobramycin?
Nephrotoxicity (reversible), ototoxicity (irreversible), neuromuscular blockade (rare), and hypersensitivity.
56
What is the mechanism of action of Sulfacetamide Sodium?
Blocks the synthesis of dihydrofolic acid by inhibiting the enzyme dihydropteroate synthase; inhibits DNA synthesis by preventing tetrahydrofolic acid formation.
57
What are the indications for Sulfacetamide Sodium?
Conjunctivitis and other superficial ocular infections.
58
What are the adverse effects of Sulfacetamide Sodium?
Hypersensitivity and blood dyscrasias.
59
What is the spectrum of activity of Sulfacetamide Sodium?
Effective against gram-positive and gram-negative bacteria.
60
What is the mechanism of action of Polymyxin B?
Alters the cytoplasmic membrane causing cellular leakage, disrupts bacterial cell membrane structure, and binds to the lipid A portion of endotoxin, inactivating it.
61
What are the indications for Polymyxin B?
Conjunctivitis, blepharitis, keratitis, and superficial infections.
62
What are the adverse effects of Polymyxin B?
Nephrotoxicity and hypersensitivity.
63
What bacteria are targeted by Polymyxin B?
Gram-negative bacteria including Enterobacter, E. coli, Klebsiella, Salmonella, Pseudomonas aeruginosa, and others.
64
What is the mechanism of action of Besifloxacin?
Inhibits DNA gyrase (in gram-negative bacteria) and topoisomerase IV (in gram-positive bacteria), preventing DNA unwinding required for replication.
65
What are the key adverse effects of Besifloxacin?
Nausea, diarrhea, skin rashes, QTc prolongation, and risk of tendinitis or tendon rupture.
66
Why is Besifloxacin contraindicated in patients under 18 years old?
Due to the possibility of damage to growing cartilage.
67
What infections can Besifloxacin treat?
UTIs, lower respiratory tract infections, conjunctivitis, keratitis, bone/joint infections, sinusitis, and more.
68
What are the drug interactions of Besifloxacin?
Enhances warfarin effects, prolongs theophylline elimination, and increases CNS stimulation risk with NSAIDs.
69
What is the mechanism of action of Ciprofloxacin?
Inhibits DNA gyrase and topoisomerase IV, preventing DNA replication and transcription.
70
What is the oral bioavailability of Ciprofloxacin?
0.7
71
What are the common indications for Ciprofloxacin?
Conjunctivitis, keratitis, respiratory tract infections, UTIs, and GI tract infections.
72
What are the adverse effects of Ciprofloxacin?
Nausea, diarrhea, QTc prolongation, CNS effects, and tendon rupture risk.
73
How is Ciprofloxacin eliminated from the body?
Through tubular secretion or glomerular filtration, with 65% urinary excretion.
74
What is the mechanism of action of Ofloxacin?
Inhibits DNA gyrase and topoisomerase IV, disrupting DNA replication and transcription.
75
What is the oral bioavailability of Ofloxacin?
0.95
76
What are the common indications for Ofloxacin?
Conjunctivitis, keratitis, sinusitis, chronic bronchitis, UTIs, and GI tract infections.
77
What are the key adverse effects of Ofloxacin?
QTc prolongation, nausea, diarrhea, tendon rupture risk, and hypersensitivity.
78
Why should Ofloxacin be avoided in young children and pregnant patients?
Due to the risk of tendon rupture and cartilage damage.
79
What drug interactions are associated with Ofloxacin?
Enhanced warfarin effects, prolonged theophylline elimination, and blood glucose disturbances with antidiabetics.
80
What are the administration routes for Levofloxacin?
Topical 0.5% and 1.5% solution, IV, IM, SC, intrathecal, intraperitoneal
81
What is the bioavailability of Levofloxacin?
24-38%
82
What is the peak serum concentration of Levofloxacin?
5.7 mcg/mL
83
What is the distribution volume (D) of Levofloxacin?
89-112 L, rapid and extensive skin tissue and blister fluid penetration, penetrates well into lung tissue
84
How is Levofloxacin excreted?
In the urine through tubular secretion and glomerular filtration
85
What is the mechanism of action of Levofloxacin?
Bactericidal; prevents DNA unwinding required for transcription and translation by inhibiting DNA gyrase and topoisomerase IV
86
What mechanisms lead to resistance to Levofloxacin?
Alteration of membrane permeability into the bacterial cell and microbial modification of DNA gyrase structure
87
What aerobic gram-positive organisms is Levofloxacin effective against?
Enterococcus faecalis, Methicillin-susceptible S. aureus, Methicillin-resistant S. epidermidis, S. saprophyticus, S. pneumoniae, S. pyogenes
88
What aerobic gram-negative organisms is Levofloxacin effective against?
Enterobacter cloacae, E. coli, H. influenzae, H. parainfluenzae, K. pneumoniae, Legionella pneumophila, M. catarrhalis, P. mirabilis, P. aeruginosa, Serratia marcescens
89
What are common adverse effects of Levofloxacin?
Nausea, diarrhea, skin rashes, abnormal LFTs, CNS effects like headache, dizziness, and tremor, QTc prolongation, risk of tendinitis and tendon rupture
90
What are important drug interactions with Levofloxacin?
Prolonged elimination half-life and elevated serum theophylline levels, enhanced effects of warfarin, NSAIDs may increase CNS stimulation and convulsive seizures, disturbance of blood glucose with antidiabetic agents
91
What are the administration routes for Moxifloxacin?
Topical 0.5% solution, PO, IV
92
What is the oral bioavailability of Moxifloxacin?
>85%
93
What is the peak serum concentration of Moxifloxacin?
3.1 mcg/mL
94
What is the half-life (t1/2) of Moxifloxacin?
9-10 hours
95
How is Moxifloxacin metabolized?
Hepatically
96
What is the mechanism of action of Moxifloxacin?
Bactericidal; interferes with topoisomerases II and IV, inhibiting DNA replication, repair, and transcription
97
What organisms is Moxifloxacin effective against?
Similar spectrum as Levofloxacin, including gram-positive cocci, gram-negative bacilli, and atypicals
98
What are the contraindications for using Moxifloxacin?
Patients younger than 18 years, pregnancy due to risk of cartilage damage
99
What are common adverse effects of Moxifloxacin?
Nausea, diarrhea, skin rashes, abnormal LFTs, CNS effects, QTc prolongation
100
What are important drug interactions with Moxifloxacin?
Similar to Levofloxacin: prolonged elimination half-life, enhanced effects of warfarin, risk of CNS stimulation with NSAIDs
101
What is the administration route for Gatifloxacin?
Topical 0.3% solution, PO
102
What is the oral bioavailability of Gatifloxacin?
0.95
103
What is the peak serum concentration of Gatifloxacin?
3.4 mcg/mL
104
What is the half-life (t1/2) of Gatifloxacin?
8 hours
105
How is Gatifloxacin excreted?
Renally
106
What is the mechanism of action of Gatifloxacin?
Bactericidal; prevents DNA unwinding required for transcription and translation by inhibiting DNA gyrase and topoisomerase IV

OPHTHALMOLOGY (4 decks)

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