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DENT 319 - Pharmacology > Antivirals and Antifungals > Flashcards

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

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2
Q

4 antifungal agents for treatment of oral candidiasis in immunocompromised patients

A
  • Nystatin oral suspension
  • Fluconazole
  • Itraconazole
  • Ketoconazole
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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

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4
Q

Dosage of fluconazole for treatment of oral candidiasis in immunocompromised patients

A

100 mg once daily po x 1-2 weeks

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5
Q

Dosage of itraconazole for the treatment of oral candidiasis in immunocompromized patients

A

200 mg once daily po x 1 - 2 weeks

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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

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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
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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
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9
Q

Nystatin drug interactions

A

No significant drug interactions

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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
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11
Q

What kind of agent is ketoconazole

A

Imidazole antifungal agent

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12
Q

Describe the function of ketoconazole

A

Disrupts the fungal cell wall

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13
Q

2 indications for ketoconazole

A
  • Systemic fungal infections
  • Severe resistant mucocutaneous candidiasis
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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
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15
Q

4 adverse effects of ketoconazole

A
  • Possible fatal drug-induces hepatitis
  • Oral lichenoid reactions
  • Nausea
  • Vomiting
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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)
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17
Q

Interaction of ketoconazole with alcohol

A

Disulfiram-like reaction

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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
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19
Q

Effect of antacids and proton pump inhibitors on ketoconazole

A

Drugs which increase gastric pH decrease ketoconazole absorption

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20
Q

Possible effect of ketoconazole on warfarin

A

May increase its anticoagulation effect (monitor INR)

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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
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22
Q

What type of agent is fluconazole (diflucan, apo-fluconazole)

A

Triazole antifungal agent

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23
Q

2 indications for fluconazole

A
  • Treatment of serious fungal infections, including oropharyngeal and eosophageal candidiasis
  • Systemic candidiasis
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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
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25
Q

Describe the absorption and excretion of fluconazole

A
  • Well-absorbed, widely distributed
  • Over 80% excreted unchanged by the kidneys
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26
Q

4 adverse effects of fluconazole

A
  • Hepatotoxicity (fatal in some pts)
  • Exfolative skin disorders (including erythema multiforme, Stevens-Johnson syndrome)
  • Toxicity may occur in pts with renal failure
  • Headache
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27
Q

5 interactions of fluconazole with other drugs

A
  • 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
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28
Q

Fluconazole dosage

A

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

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29
Q

What type of agent is itraconazole

A

Triazoole antifungal agent

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30
Q

Function of itraconazole

A

Blocks synthesis of essential membrane sterols in fungal organisms

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31
Q

Indication for itraconazole

A

Treatment of severe fungal infections of the oral cavity or esophagus

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32
Q

Form of itraconazole indicated for the treatment of oral and/or esophageal candidiasis in adult HIV-positive or other immunocompromised patients

A

Sporanox oral solution 10 mg/mL

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33
Q

5 adverse effects of itraconazole

A
  • Hepatoxicity
  • Excessive fatigue
  • Increased BP and edema (avoid in pts w/ CHF hx)
  • Nausea, vomiting, diarrhea
  • Stevens-Johnson syndrome
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34
Q

4 drug interactions of itraconazole

A
  • 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
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35
Q

Recommended dosage of itraconazole oral solution from oral candiasis

A

200 mg qd in single or divided doses for 1-2 weeks

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36
Q

Recommended dosage of itraconazole for esophageal candidiasis

A

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

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37
Q

Primary action of clotrimazole

A

Counteracts dividing and growing organisms, possibly through reaction with the cell membrane

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38
Q

Indication for clotrimazole

A

Angular cheilitis

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39
Q

Prescription for lotriderm cream (clotrimazole)

A
  • 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
Q

How to confirm diagnosis of most cases of oral candidiasis

A

Cytologic smear or fungal culture (CFU stick with Nystatin suspension)

41
Q

4 forms of acyclovir

A
  • Cream
  • Ointment
  • Tablets
  • Sodium injection
42
Q

3 indications for acyclovir

A
  • Primary herpes simplex infections (HSV1, HSV2) oral & genital
  • Recurrent herpes simplex virus infection
  • Herpes labialis
43
Q

2 means of diagnosing herpes simplex virus

A
  • Tzanck smears prepared from lesion exudate or scrapings may assist in diagnosis
  • Postivie culturs for HSV offer the only ABSOLUTE means for confirmation
44
Q

Action of acyclovir

A

Synthetic acyclic purine nucleoside analogue that inhibits viral DNA replication by interfering with viral DNA polymerase

45
Q

Indication for acyclovir cream 5%

A

Recurrent herpes labialis

46
Q

Sample prescription for recurent herpes labialis

A
  • 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
Q

Available dose of acyclovir tablets

A

200 mg

48
Q

Available dosage of acyclovir suspension

A

200 mg/5mL

49
Q

4 indications for acyclovir tablets/suspension

A
  • 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
Q

Contraindications for acyclovir

A
  • 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
Q

3 adverse effects of acyclovir

A
  • Nausea
  • GI distress
  • Headache
52
Q

Treatment of initial infection of herpes genitalis or AHGS with acyclovir

A
  • 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
Q

Treatment of herpes zoster with acyclovir

A
  • 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
Q

Treatment of chickenpox with acyclovir

A
  • 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
Q

Suppressive therapy for recurrent herpes genitalis with acyclovir

A
  • 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
Q

Intermittent therapy for herpes genitalis with acyclovir

A
  • 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
Q

2 indications for acyclovir injection

A

HSV-induced:

  • Encephalitis
  • Moderate to severe mucocutaneous lesions in immunocompromised patients
58
Q

Usual dose of acyclovir for HSV-induced encephalitis

A

10 mg/kg q8h x 14-21 days

59
Q

Available form of injectable acyclovir

A

5 mg/kg q8h

60
Q

Available dosage of zovirax

A

200 mg tabs or 5mL suspension

61
Q

Usual dose of IV acyclovir for HSV-induced moderate to severe mucocutaneous lesions in immunocompromised patients

A

5 mg/kg q8h

NOTE: switch to oral antiviral formulation when lesions start to regress and continue until all lesions healed

62
Q

3 indications of valacyclovir (valtrex)

A
  • Antiviral
  • Herpes simplex viral infections
  • Herpes zoster
63
Q

What type of drug is valacyclovir

A

Prodrug (ester of acyclovir)

64
Q

Describe the function of valacylovir

A
  • Converted to acyclovir during first pass intestinal or hepatic metabolism
  • Inhibits viral DNA replication by interering with viral DNA polymerase
65
Q

3 serious adverse drug reactions of valacyclovir

A
  • Thrombotic Thrombocytopenis Purpura/ Hemolytic Uremic Syndrome
  • Acute Renal Failure
  • Central Nervous System Effects
66
Q

4 adverse effects of valacyclovir

A
  • 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
Q

Treatment of herpes zoster with valacyclovir

A
  • Recommended dosage of valtrex = 1000 mg orally 3x daily for 7 days
  • Should be initiated within 72 hours of onset of rash
68
Q

Treatment of initial episode of genital herpes and acute herpetic gingivostomatitis with valacyclovir

A
  • 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
Q

Treatment of recurrent episodes of genital herpes and recurrent herpes labialis/intraoral with valacyclovir

A
  • Recommended dosage = 500 mg caps orally bid x 3 days
  • Therapy should be initiated at earliest sign/symptom of recurrence. May prevent lesion.
70
Q

Chronic suppression of genital herpes/herpes labialis with valacyclovir

A
  • 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
Q

Safe and tolerable dose of valtrex for long term therapy

A
  • 1000 mg qd for up to 1 year
  • 500 mg qd for up to 20 months
72
Q

Reduction of transmission of genital herpes with valacyclovir

A
  • 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
Q

Treatment of cold sores (herpes labialis) with valacyclovir

A
  • 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
Q

2 available dosages of valtrex

A
  • 500 mg tabs
  • 1000 mg tabs
75
Q

3 indications of famciclovir

A
  • 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
Q

What kind of drug is famciclovir

A

Ester prodrug that converts to penciclovir

77
Q

Describe the function of famciclovir

A
  • 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
Q

Treatment for herpes zoster with famciclovir

A
  • 500 mg tid x 7 days
  • Initiate therapy within 72 hrs of rash onset
79
Q

Patients most likely to benefit from decreased duration of post-herpetic neuralgia from herpes zoster with famciclovir treatment

A
  • 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
Q

Treatment of recurrent genital herpes episodes (recurrent herpes labialis) with famciclovir

A
  • 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
Q

Suppression of recurrent genital herpes episodes with famciclovir

A
  • Recommended dose = 250 mg bid for up to 1 year
82
Q

3 adverse effects of famciclovir

A
  • Headache (inc. migraine)
  • Nausea
  • Diarrhea

NOTE: no documented drug-drug interactions

83
Q

3 dosage forms of famciclovir

A
  • 125 mg tabs
  • 250 mg tabs
  • 500 mg tabs
84
Q

Describe the function of docosanol 10% cream (abreva)

A
  • Anti-HSV acitivty = inhibition of fusion between plasma membrane and HSV envelope
  • Blocks viral entry into the cell and subsequent viral replication
85
Q

Indication for abreva (docosanol cream 10%)

A

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
Q

Treatment regimen of cold sores with abreva

A
  • 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
Q

Adverse effect of abreva

A

Tingling at application site

NOTE: No documented drug-drug interactions

88
Q

Dosage form available for abreva 10% cream

A

Tubes and pumps of 2 grams

NOTE: not for intraoral use

89
Q

Composition of xerese cream

A

Acyclovir 5% hydrocortisone 1%

90
Q

Indication of xerese

A

Treatment of early signs and symptoms of recurrent herpes labialis to reduce progression of episodes to ulcerative lesions in immunocompetent adults and adolescents

91
Q

Dosage form available for xerese

A

5 g tube ($60)

92
Q

Contraindications for xerese

A
  • 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
Q

Treatment regimen using xerese

A

Topical application to lesion (including outer margin) 5 x daily for 5 days

94
Q

Antiviral discontinued in 2009

A

Penciclovir (denavir)

95
Q

Possible best medication for herpes labialis

A

Best control with Valtrex PO

DENT 319 - Pharmacology (7 decks)

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