Nucleoside Analogues (HSV) Flashcards

1
Q

What is Acyclovir’s MOA?

A

Interferes with DNA polymerase and inhibits viral DNA synthesis

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2
Q

ADR’s related to IV Acyclovir:

A

Renal dysfunction
-acute tubular necrosis
-neurological effects (ataxia, tremor, seizures).

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3
Q

ADR’s related to PO Acyclovir:

A

Headache, skin rash, nausea, vomiting, diarrhea.

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4
Q

Major drug interactions for acyclovir:

A

-Probenecid
-Nephrotoxic drugs (e.g., aminoglycosides, amphotericin B)

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5
Q

Absorption for acyclovir:

A

Poor oral bioavailability (15-20%)

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6
Q

Distribution for acyclovir:

A

Good CSF penetration.
Cross placenta and found in breast milk.

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7
Q

What is acyclovir used for?

A

-Herpes Zoster, HSV & varicella zoster
-genital herpes & varicella

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8
Q

How is acyclovir metabolized & excreted?

A

-Minimal hepatic metabolism
-excreted 90% unchanged in urine

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9
Q

What is unique about Valacyclovir’s MOA?

A

Prodrug which is converted to acyclovir after PO administration

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10
Q

ADR’s for valacyclovir:

A

Same ones as acyclovir but higher incidence;

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11
Q

Serious ADR’s for valacyclovir in immunocompromised patients:

A

Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS)

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12
Q

Drug interactions for Valacyclovir:

A

-Probenecid
-Nephrotoxic drugs (e.g., aminoglycosides, amphotericin B)

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13
Q

Valacyclovir Pharmacokinetics:

A

Similar to acyclovir after being converted

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14
Q

MOA of Famciclovir:

A

Prodrug converted to penciclovir, which inhibits viral DNA synthesis.

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15
Q

ADR’s for Famciclovir:

A

Headache, dizziness, somnolence, paresthesias.

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16
Q

Major Drug interactions for Famciclovir:

A

Cimetidine: Increases penciclovir levels.
Theophylline: Increases penciclovir area under the curve (AUC).
Digoxin: Minor increase in digoxin levels.

17
Q

How is Famciclovir absorbed & distributed?

A

rapidly absorbed & metabolized to penciclovir

widely distributed

18
Q

Famciclovir metabolism & Excretion:

A

Metabolized to penciclovir in the intestine and liver.

Renal excretion.

19
Q
A