Antivirals and Antifungals Flashcards
1
Q
Antifungal for treatment of oral candidiasis for immunocompetent patients (give agent and dose)
A
Nystatin oral suspension swish and swallow 400,000 - 600,000 units QID x 14 days
2
Q
4 antifungal agents for treatment of oral candidiasis in immunocompromised patients
A
- Nystatin oral suspension
- Fluconazole
- Itraconazole
- Ketoconazole
3
Q
Dosage of nystatin oral suspension in the treatment of oral candidiasis for immunocompromised patients
A
Swish and swallow 500,000 - 1,000,000 units QID x 14 days
4
Q
Dosage of fluconazole for treatment of oral candidiasis in immunocompromised patients
A
100 mg once daily po x 1-2 weeks
5
Q
Dosage of itraconazole for the treatment of oral candidiasis in immunocompromized patients
A
200 mg once daily po x 1 - 2 weeks
6
Q
Dosage of ketoconazole in the treatment of oral candidiasis for immunocompromized patients
A
200 - 400 mg once daily po x 1-2 weeks
7
Q
Describe the function of nystatin oral suspension (ratio-Nystatin)
A
- Binds to fungal cell wall membrane –> leakage of cellular contents
- Primary local/topical action (not systemic)
- Poorly absorbed by GIT, excreted unchanged in feces after oral admin
8
Q
6 possible adverse effects of nystatin
A
Generally very safe drug w/ no significant side effects, but may cause:
- GI upset
- Gas
- Bloating
- Diarrhea
- Nausea
- Vomiting
9
Q
Nystatin drug interactions
A
No significant drug interactions
10
Q
3 methods of nystatin administration and their respective dosages
A
- Nystatin oral suspension: 100,000 units per mL.
- 5 mL qid x 10-14 days (swish and swallow)
- Nystatin tablets: 500,000 u per tab.
- 1-2 tabs tid x 7 days (?effective)
- Nystatin cream (NYADERM or RATIO-NYSTATIN)
- 100,000u per gram –> 30 g tube
NOTE: Sample Rx
- Nystatin oral susp. 100,000 u./ml.
- Disp. 200ml.
- Sig. 5ml. qid S&S x 10 days
11
Q
What kind of agent is ketoconazole
A
Imidazole antifungal agent
12
Q
Describe the function of ketoconazole
A
Disrupts the fungal cell wall
13
Q
2 indications for ketoconazole
A
- Systemic fungal infections
- Severe resistant mucocutaneous candidiasis
14
Q
Describe the absorption and metabolism of ketoconazole
A
- Absorption from the GIT is pH dependent (lower pH/more acidic = decreased absorption)
- Wide distribution
- Partially metabolized by the liver –> excreted in feces via biliary excretion
15
Q
4 adverse effects of ketoconazole
A
- Possible fatal drug-induces hepatitis
- Oral lichenoid reactions
- Nausea
- Vomiting
16
Q
5 contraindications for ketoconazole
A
- Pts with known hypersensitivity to ketoconazole
- Possible cross-sensitivty with other azole antifungals
- Pts with hepatic dysfunction
- Women of childbearing potential (unless effective forms of contraception are employed)
- Avoid use in pregnancy (crosses placental barrier)
17
Q
Interaction of ketoconazole with alcohol
A
Disulfiram-like reaction
18
Q
Effect of ketoconazole on cytochrome P450 and 6 drugs affected by this effect
A
Potent inhibitor –> decreased metabolism and increased toxicity of several drugs including:
- Calcium channel blockers
- Corticosteroids
- Macrolide antibiotics
- Benzodiazepines
- Lipid lowering agents
- Phenytoin
19
Q
Effect of antacids and proton pump inhibitors on ketoconazole
A
Drugs which increase gastric pH decrease ketoconazole absorption
20
Q
Possible effect of ketoconazole on warfarin
A
May increase its anticoagulation effect (monitor INR)
21
Q
Dosage of ketoconazole
A
Oral: 200 - 400 mg. tablets
- 1 tab qd for 1-2 wks
- Supplied as 200 mg tabs
NOTE: Sample Rx
- Ketoconazole 200 mg. tabs
- Disp. 14 tabs
- Sig. 1 tab. qd x 2 weeks
22
Q
What type of agent is fluconazole (diflucan, apo-fluconazole)
A
Triazole antifungal agent
23
Q
2 indications for fluconazole
A
- Treatment of serious fungal infections, including oropharyngeal and eosophageal candidiasis
- Systemic candidiasis
24
Q
Describe the function of fluconazole
A
- Inhibits the synthesis of fungal sterols (necessary component of fungal cell wall)
- Fungistatic: may be fungicidal at higher concentrations
25
Describe the absorption and excretion of fluconazole
* Well-absorbed, widely distributed
* Over 80% excreted unchanged by the kidneys
26
4 adverse effects of fluconazole
* Hepatotoxicity (fatal in some pts)
* Exfolative skin disorders (including erythema multiforme, Stevens-Johnson syndrome)
* Toxicity may occur in pts with renal failure
* Headache
27
5 interactions of fluconazole with other drugs
* Enhances anticoagulation effect of warfarin
* Increases hypoglycemic effects of tolbutamide and glyburide
* Inhibits metabolism of certain benzodiazepines (triazolam, midazolam)
* Phenytoin toxicity - avoid concurrent use
* Renal toxicity with concurrent cyclosporine use
28
Fluconazole dosage
100 mg qd 7 - 14 days
NOTE: for very serious systemic infections, may give up to 400 mg qd. Supplied as 50, 100, 150 and 200 mg tabs
29
What type of agent is itraconazole
Triazoole antifungal agent
30
Function of itraconazole
Blocks synthesis of essential membrane sterols in fungal organisms
31
Indication for itraconazole
Treatment of severe fungal infections of the oral cavity or esophagus
32
Form of itraconazole indicated for the treatment of oral and/or esophageal candidiasis in adult HIV-positive or other immunocompromised patients
Sporanox oral solution 10 mg/mL
33
5 adverse effects of itraconazole
* Hepatoxicity
* Excessive fatigue
* Increased BP and edema (avoid in pts w/ CHF hx)
* Nausea, vomiting, diarrhea
* Stevens-Johnson syndrome
34
4 drug interactions of itraconazole
* Inhibits metabolism of certain benzodiaepines (midazolam & triazolam)
* Increases hypoglycemic effects of oral antidiabetcs (tolbutamide & glyburide)
* Increased risk of rhabdomyolysis if taken concurrently with lovastatin or simvastatin
* Increases anticoagulation effects of warfarin
35
Recommended dosage of itraconazole oral solution from oral candiasis
200 mg qd in single or divided doses for 1-2 weeks
36
Recommended dosage of itraconazole for esophageal candidiasis
100 mg qd for min 3 weeks (treatment should continue for 2 weeks following resolution of symptoms)
May use up to 200 mg per day depending on pt response
37
Primary action of clotrimazole
Counteracts dividing and growing organisms, possibly through reaction with the cell membrane
38
Indication for clotrimazole
Angular cheilitis
39
Prescription for lotriderm cream (clotrimazole)
* Lotriderm cream
* Disp: 15 g tube
* Sig: Thin coat BID x 2 weeks
NOTE: available as 1% Canesten Topical OTC 15 & 30 g tubes or Clotrimaderm 2% vaginal cream 25 gr tube
40
How to confirm diagnosis of most cases of oral candidiasis
Cytologic smear or fungal culture (CFU stick with Nystatin suspension)
41
4 forms of acyclovir
* Cream
* Ointment
* Tablets
* Sodium injection
42
3 indications for acyclovir
* Primary herpes simplex infections (HSV1, HSV2) oral & genital
* Recurrent herpes simplex virus infection
* Herpes labialis
43
2 means of diagnosing herpes simplex virus
* Tzanck smears prepared from lesion exudate or scrapings may assist in diagnosis
* Postivie culturs for HSV offer the only ABSOLUTE means for confirmation
44
Action of acyclovir
Synthetic acyclic purine nucleoside analogue that inhibits viral DNA replication by interfering with viral DNA polymerase
45
Indication for acyclovir cream 5%
Recurrent herpes labialis
46
Sample prescription for recurent herpes labialis
* Acyclovir cream 5%
* Disp: 5 gram tube
* Sig: Apply 4-6 times daily for 7 - 10 days
NOTE: Note recommended for application to mucous membranes (i.e. mouth, vagina). Not for recurrent intraoral HSV on palate or gingiva
47
Available dose of acyclovir tablets
200 mg
48
Available dosage of acyclovir suspension
200 mg/5mL
49
4 indications for acyclovir tablets/suspension
* Treatment of initial episodes of genital herpes
* Treatment of primary AHGS
* Suppression of unusually frequent recurrences of herpes genitalis (6 or more eps/ year)
* Acute treatment of herpes zoster (shingles) and varicella (chickenpox)
50
Contraindications for acyclovir
* Renal insufficiency or acute renal failure has been observed at the recommended dosage and/or with no previous renal conditions. May be associated with renal pain
* Eliminated by renal clearance, so reduce dose in renal impairment
51
3 adverse effects of acyclovir
* Nausea
* GI distress
* Headache
52
Treatment of initial infection of herpes genitalis or AHGS with acyclovir
* 200 mg (one 200 mg tablet or one tsp of 5mL suspension every 4 hours, 5 x daily for total of 1 g daily for 10 days)
* Therapy should be initiated asap following onset of signs and symptoms
53
Treatment of herpes zoster with acyclovir
* 800 mg of oral Zorivax every 4 hrs, 5x daily for 7-10 days
* Treatment should be intiiated within 72 hours of onset of lesions
* Greatest benefit if started within 48 hrs
54
Treatment of chickenpox with acyclovir
* 20 mg/kg (not to exceed 800 mg) orally, 4x daily for 5 days
* Should be initiated within 24 hours of appearance of rash
55
Suppressive therapy for recurrent herpes genitalis with acyclovir
* Initial recommended dose = 200 mg 3 x daily
* Increase up to 200 mg 5 x daily if breakthrough occurs
* 400 mg 2 x daily may be considered
* Periodic re-eval for need for therapy is recommended
56
Intermittent therapy for herpes genitalis with acyclovir
* 200 mg ZOVIRAX every 4 hours 5 x daily for 5 days
* Therapy should be initiated at earliest sign or symptom (prodrome) of recurrence
57
2 indications for acyclovir injection
HSV-induced:
* Encephalitis
* Moderate to severe mucocutaneous lesions in immunocompromised patients
58
Usual dose of acyclovir for HSV-induced encephalitis
10 mg/kg q8h x 14-21 days
59
Available form of injectable acyclovir
5 mg/kg q8h
60
Available dosage of zovirax
200 mg tabs or 5mL suspension
61
Usual dose of IV acyclovir for HSV-induced moderate to severe mucocutaneous lesions in immunocompromised patients
5 mg/kg q8h
NOTE: switch to oral antiviral formulation when lesions start to regress and continue until all lesions healed
62
3 indications of valacyclovir (valtrex)
* Antiviral
* Herpes simplex viral infections
* Herpes zoster
63
What type of drug is valacyclovir
Prodrug (ester of acyclovir)
64
Describe the function of valacylovir
* Converted to acyclovir during first pass intestinal or hepatic metabolism
* Inhibits viral DNA replication by interering with viral DNA polymerase
65
3 serious adverse drug reactions of valacyclovir
* Thrombotic Thrombocytopenis Purpura/ Hemolytic Uremic Syndrome
* Acute Renal Failure
* Central Nervous System Effects
66
4 adverse effects of valacyclovir
* Renal insufficiency or acute renal failure have been observed in pts taking VALTREX at recommended dosage and/or with no previous renal conditions. May be associated w/ renal pain
* Headache
* Nausea
* GI distress
67
Treatment of herpes zoster with valacyclovir
* Recommended dosage of valtrex = 1000 mg orally 3x daily for 7 days
* Should be initiated within 72 hours of onset of rash
68
Treatment of initial episode of genital herpes and acute herpetic gingivostomatitis with valacyclovir
* Recommended dosage = 1000 mg valtrex caps 2 bid for 10 days
* Most effective when administered within 48 hrs of onset of signs and symptoms
69
Treatment of recurrent episodes of genital herpes and recurrent herpes labialis/intraoral with valacyclovir
* Recommended dosage = 500 mg caps orally bid x 3 days
* Therapy should be initiated at earliest sign/symptom of recurrence. May prevent lesion.
70
Chronic suppression of genital herpes/herpes labialis with valacyclovir
* Recommended dosage = 1000 mg orally qd in pts with normal immune function
* Pts w/ a hx of 9 or fewer recurrences per year = 500 mg orally qd alternative
71
Safe and tolerable dose of valtrex for long term therapy
* 1000 mg qd for up to 1 year
* 500 mg qd for up to 20 months
72
Reduction of transmission of genital herpes with valacyclovir
* Pts w/ hx of 9 or fewer recurrences per year = 500 mg qd for source partner
* Efficacy of reducing transmission beyond 8 months in couples discordant for HSV-2 infection has not been established
73
Treatment of cold sores (herpes labialis) with valacyclovir
* Recommended dosage = 2000 mg orally bid for 1 day
* Second dose should be taken approx 12 hours after first, but not less than 6 hours after first dose
* Therapy should be initiated at earliest symptom (tingling, itching, burning)
* No data on efficacy of treatment initiated after development of clinical signs of cold sore
74
2 available dosages of valtrex
* 500 mg tabs
* 1000 mg tabs
75
3 indications of famciclovir
* Treatment of acute herpes zoster
* Treatment or suppression of recurrent episodes of genital herpes in immunocompetent adults
* Treatment of recurrent episodes of mucocutaneous herpes simplex infections in HIV-infected patients
76
What kind of drug is famciclovir
Ester prodrug that converts to penciclovir
77
Describe the function of famciclovir
* Conversion to penciclovir during passage from GIT to systemic circulation
* Penciclovir = guanine nucleoside analogue, similar in structure to acyclovir
* Inhibits viral DNA replication by interfering with viral DNA polymerase --\> effective when virus is replicating
78
Treatment for herpes zoster with famciclovir
* 500 mg tid x 7 days
* Initiate therapy within 72 hrs of rash onset
79
Patients most likely to benefit from decreased duration of post-herpetic neuralgia from herpes zoster with famciclovir treatment
* Pts who initiate treatment within 48 hrs of onset of rash
* Pts greater than 50 yrs of age
* Pts w/ severe pain at time of treatment initiation
80
Treatment of recurrent genital herpes episodes (recurrent herpes labialis) with famciclovir
* 125 mg bid x 5 days
* Initiation recommended during prodromal period or asap at first sign or symptom (tingling, itching, burning, pain, or lesion)
81
Suppression of recurrent genital herpes episodes with famciclovir
* Recommended dose = 250 mg bid for up to 1 year
82
3 adverse effects of famciclovir
* Headache (inc. migraine)
* Nausea
* Diarrhea
NOTE: no documented drug-drug interactions
83
3 dosage forms of famciclovir
* 125 mg tabs
* 250 mg tabs
* 500 mg tabs
84
Describe the function of docosanol 10% cream (abreva)
* Anti-HSV acitivty = inhibition of fusion between plasma membrane and HSV envelope
* Blocks viral entry into the cell and subsequent viral replication
85
Indication for abreva (docosanol cream 10%)
Treatment of acute episodes of recurrent oral-facial herpes simplex in adults (shortens healing time and duration of cold sore symptoms --\> soothes on contact)
86
Treatment regimen of cold sores with abreva
* Apply topically 5 x daily until lesion is healed up to max 10 days
* Begin treatment asap, preferably at prodrome or erythema stage (most effective prior to formation of a papule or blister)
87
Adverse effect of abreva
Tingling at application site
NOTE: No documented drug-drug interactions
88
Dosage form available for abreva 10% cream
Tubes and pumps of 2 grams
NOTE: not for intraoral use
89
Composition of xerese cream
Acyclovir 5% hydrocortisone 1%
90
Indication of xerese
Treatment of early signs and symptoms of recurrent herpes labialis to reduce progression of episodes to ulcerative lesions in immunocompetent adults and adolescents
91
Dosage form available for xerese
5 g tube ($60)
92
Contraindications for xerese
* Do not use in or near eyes, inside mouth or nose, on genitals or rectal area
* Not recommended for mucous membranes
* Not for other orofacial lesions such as bacterial or fungal infections
93
Treatment regimen using xerese
Topical application to lesion (including outer margin) 5 x daily for 5 days
94
Antiviral discontinued in 2009
Penciclovir (denavir)
95
Possible best medication for herpes labialis
Best control with Valtrex PO
