Foscarnet Sodium and High Blood Pressure (Hypertension)

• Generic Name: foscarnet
• Dosage Forms: n.a.
• Other Brand Names: Foscavir

Initial treatment (induction therapy) and maintenance therapy (secondary prophylaxis) of CMV retinitis in HIV-infected adults, including those with acquired immunodeficiency syndrome (AIDS). Also used for management of CMV retinitis in HIV-infected pediatric patients.

Safety and efficacy not established for treatment of CMV retinitis in immunocompetent individuals.

Like other antivirals, foscarnet is not a cure for CMV retinitis; stabilization or improvement of ocular manifestations may occur, but relapse and/or progression of CMV retinitis possible during or following foscarnet therapy.

Retinitis is the most common clinical manifestation of CMV end-organ disease in HIV-infected patients; ideally should be managed in consultation with an ophthalmologist familiar with diagnosis and treatment of retinal diseases.

Select antiviral regimen for initial treatment of CMV retinitis in HIV-infected individuals based on location and severity of the CMV retinal lesions, severity of underlying immunosuppression, concomitant drug therapy, and patient’s ability to adhere to the treatment regimen. Select antiviral regimen for maintenance therapy based on location of CMV retinal lesions, vision in contralateral eye, patient's immunologic and virologic status, and patient's response to antiretroviral therapy.

For management of immediate sight-threatening CMV retinal lesions (i.e., within 1.5 mm of the fovea) in HIV-infected adults and adolescents, CDC, NIH, and IDSA state that the preferred regimen is initial treatment (induction therapy) with intravitreal ganciclovir or intravitreal foscarnet (1–4 doses over 7–10 days) in conjunction with oral valganciclovir (twice daily for 14–21 days) followed by maintenance therapy (secondary prophylaxis) with oral valganciclovir (once daily). One alternative regimen recommended by these experts for sight-threatening CMV retinitis in HIV-infected adults and adolescents is intravitreal ganciclovir or intravitreal foscarnet (1–4 doses over 7–10 days) in conjunction with IV foscarnet (2 or 3 times daily for 2–3 weeks) followed by maintenance therapy (secondary prophylaxis) with IV foscarnet (once daily). Systemic antivirals (without an intravitreal antiviral) usually adequate for management of CMV retinitis in patients with only small peripheral lesions.

For management of CMV retinitis in HIV-infected pediatric patients, CDC, NIH, IDSA, and others state that IV ganciclovir is drug of choice for initial treatment (induction therapy) and one of several options for maintenance therapy (secondary prophylaxis). These experts state that IV foscarnet is a preferred alternative for management of CMV retinitis in HIV-infected children and is recommended for infections known or suspected to be caused by ganciclovir-resistant CMV. These experts state that a regimen of IV ganciclovir and IV foscarnet can be considered for initial treatment (induction therapy) in HIV-infected children with sight-threatening CMV retinitis or when the infection failed to respond to or relapsed after monotherapy. Data are limited regarding use of intravitreal antivirals in children; intravitreal injections are impractical in most children.

Because of risk of relapse, chronic maintenance therapy (secondary prophylaxis) of CMV retinitis usually continued until immune reconstitution occurs as a result of effective antiretroviral therapy. CDC, NIH, and IDSA state that discontinuance of maintenance therapy of CMV retinitis can be considered in HIV-infected adults and adolescents if CMV lesions have been treated for ≥3–6 months and are inactive and there has been a sustained (i.e., 3–6 months) increase in CD4+ T-cell count to >100/mm3 in response to antiretroviral therapy. Although safety of discontinuing maintenance therapy of CMV retinitis in HIV-infected pediatric patients not well studied, discontinuance of such therapy can be considered in those receiving antiretroviral therapy who have a sustained (i.e., >6 months) increase in CD4+ T-cell percentage to >15% (children <6 years of age) or increase in CD4+ T-cell count to >100/mm3 (children ≥6 years of age).

If maintenance therapy of CMV retinitis is discontinued, continue regular ophthalmologic monitoring (optimally every 3–6 months) for early detection of CMV relapse or immune reconstitution uveitis. If CD4+ T-cell count decreases to <100/mm3 (adults, adolescents, children ≥6 years of age) or CD4+ T-cell percentage decreases to <15% (children <6 years of age), reinitiate CMV retinitis maintenance therapy.

Safety and efficacy not established for management of extraocular CMV infections (e.g., pneumonitis, gastroenteritis) or for congenital or neonatal CMV disease.

CDC, NIH, and IDSA state that IV ganciclovir usually is the preferred antiviral for initial management of CMV GI disease; however, IV foscarnet is a possible alternative for management of CMV esophagitis or colitis in HIV-infected adults who cannot receive ganciclovir or have infections caused by ganciclovir-resistant CMV.

For management of well-documented CMV pneumonitis in HIV-infected adults, CDC, NIH, and IDSA state that either IV ganciclovir or IV foscarnet is a reasonable choice.

Combination regimen of IV ganciclovir and IV foscarnet has been used for management of CMV neurologic disease (e.g., CMV encephalitis or myelitis) and is recommended by CDC, NIH, IDSA, and others for such infections in HIV-infected individuals.

Has been used for prophylaxis or preemptive antiviral treatment of CMV infection and disease in hematopoietic stem cell transplant (HSCT) recipients.

Although safety and efficacy not established, IV foscarnet is considered a second-line or alternative antiviral for prophylaxis or preemptive treatment of CMV infection in HSCT recipients; usually reserved for resistant and refractory CMV infections or when first-line antivirals cannot be used because of intolerance.

Also recommended as a second-line or alternative antiviral for treatment of CMV infection in solid organ transplant recipients when first-line antivirals cannot be used because of resistance or intolerance.

Management of mucocutaneous infections (e.g., orofacial, genital, digital) caused by acyclovir-resistant HSV types 1 and 2 (HSV-1 and HSV-2) in immunocompromised individuals, including those with AIDS.

Safety and efficacy not established for treatment of other HSV infections (e.g., retinitis, encephalitis), congenital or neonatal HSV disease, or HSV infections in immunocompetent individuals.

Drugs of choice for management of orolabial lesions or initial or recurrent genital lesions caused by HSV are valacyclovir, famciclovir, and acyclovir.

For management of mucocutaneous lesions caused by acyclovir-resistant HSV in HIV-infected adults, adolescents, and children, CDC, NIH, IDSA, and others recommend IV foscarnet as drug of choice.

Like other antivirals, foscarnet is not a cure for mucocutaneous HSV infections. While complete healing is possible, relapse occurs in most patients. Resistance may develop following repeated foscarnet treatment. In vitro susceptibility testing advised if there is a poor therapeutic response to the drug.

Management of acyclovir-resistant VZV infections in immunocompromised patients, including those with AIDS.

Preferred antivirals for management of acute, localized herpes zoster (shingles) in HIV-infected adults and adolescents are acyclovir, famciclovir, and valacyclovir. For management of proven or suspected acyclovir-resistant VZV infections in HIV-infected adults or adolescents, CDC, NIH, and IDSA recommend IV foscarnet.

In HIV-infected children, acyclovir is drug of choice for treatment of VZV infections and foscarnet is the preferred alternative for treatment of acyclovir-resistant VZV infections.

Although optimal regimens for management of progressive outer retinal necrosis caused by VZV not identified, CDC, NIH, and IDSA recommend that HIV-infected adults and adolescents be treated with at least one IV antiviral (acyclovir, ganciclovir, foscarnet, cidofovir) used in conjunction with at least one intravitreal antiviral (ganciclovir or foscarnet). Prognosis for visual preservation in patients with progressive outer retinal necrosis caused by VZV is poor; such infections should be managed in consultation with an ophthalmologist.