12-17-2008, 04:36 AM
Correct Answer = D)
Key Points
* Administration of foscarnet is indicated for a patient with acyclovir-resistant herpes simplex virus infection.
* Administration of foscarnet may be associated with significant electrolyte abnormalities.
This patient has clinical evidence of an acyclovir-resistant herpes simplex virus infection. Although the dose of acyclovir is higher than normally used for treatment of cutaneous herpes simplex virus infections, there is no evidence of healing. He should therefore be started on foscarnet, which is a pyrophosphate analogue that binds to viral DNA and has a different mechanism of action than the other medications listed. Because administration of foscarnet can cause significant electrolyte abnormalities, routine laboratory studies are indicated before beginning this drug.
Valacyclovir, famciclovir, and ganciclovir should not be used because all three drugs show cross resistance in clinical circumstances such as these. Cidofovir may also be used in the treatment of acyclovir-resistant herpes simplex virus infection. However, cidofovir would not be the initial drug of choice because it is associated with nephrotoxicity and would exacerbate the patient's renal dysfunction.
Bibliography
Key Points
* Administration of foscarnet is indicated for a patient with acyclovir-resistant herpes simplex virus infection.
* Administration of foscarnet may be associated with significant electrolyte abnormalities.
This patient has clinical evidence of an acyclovir-resistant herpes simplex virus infection. Although the dose of acyclovir is higher than normally used for treatment of cutaneous herpes simplex virus infections, there is no evidence of healing. He should therefore be started on foscarnet, which is a pyrophosphate analogue that binds to viral DNA and has a different mechanism of action than the other medications listed. Because administration of foscarnet can cause significant electrolyte abnormalities, routine laboratory studies are indicated before beginning this drug.
Valacyclovir, famciclovir, and ganciclovir should not be used because all three drugs show cross resistance in clinical circumstances such as these. Cidofovir may also be used in the treatment of acyclovir-resistant herpes simplex virus infection. However, cidofovir would not be the initial drug of choice because it is associated with nephrotoxicity and would exacerbate the patient's renal dysfunction.
Bibliography