Antiviral drugs

Antiviral drugs

The majority of virus infections resolve spontaneously in immunocompetent subjects. A number of specific treatments for viral infections are available, particularly for the immunocompromised.

Herpesvirus infections

The two most important herpesvirus pathogens are herpes simplex virus (herpesvirus hominis) and varicella–zoster virus.

ACICLOVIR:

Indications: Chickenpox, Herpes Genitalis, Herpes Labialis, Herpes Simplex Encephalitis, Herpes Simplex Infection, Herpes Zoster, Mucocutaneous Herpes Simplex, Recurrent Herpes Genitalis, Recurrent Mucocutaneous Herpes Simplex, Suppression of Recurrent Herpes Simplex Infection.

Contraindications: Dehydration, Renal Disease.

Dose and Administration: By mouth, herpes simplex, treatment, 200 mg (400 mg in the immunocompromised or if absorption impaired) 5 times daily, usually for 5 days (longer if new lesions appear during treatment or if healing incomplete; increase dose to 800 mg 5 times daily for genital herpes in the immunocompromised); child under 2 years, half adult dose, over 2 years, adult dose. Herpes simplex, prevention of recurrence, 200 mg 4 times daily or 400 mg twice daily possibly reduced to 200 mg 2 or 3 times daily and interrupted every 6–12 months. Herpes simplex, prophylaxis in the immunocompromised, 200– 400 mg 4 times daily; child under 2 years, half adult dose, over 2 years, adult dose. Varicella and herpes zoster, treatment, 800 mg 5 times daily for 7 days; child, varicella, 20 mg/kg (max. 800 mg) 4 times daily for 5 days or under 2 years 200 mg 4 times daily, 2–5 years 400 mg 4 times daily, over 6 years 800 mg 4 times daily.

FAMCICLOVIR:

Indications: Herpes Genitalis, Herpes Labialis, Herpes Zoster, Recurrent Herpes Genitalis, Recurrent Herpes Simplex, Recurrent Mucocutaneous Herpes Simplex in Human Immunodeficiency Virus Infected Patients, Suppression of Recurrent Herpes Simplex Infection.

Contraindications: Renal Disease

Dose and Administration: Herpes zoster, 250 mg 3 times daily for 7 days or 750 mg once daily for 7 days (in immunocompromised, 500 mg 3 times daily for 10 days). Genital herpes, first episode, 250 mg 3 times daily for 5 days (longer if new lesions appear during treatment or if healing incomplete); recurrent infection, 125 mg twice daily for 5 days (in immunocompromised, all episodes, 500 mg twice daily for 7 days). Genital herpes, suppression, 250 mg twice daily (in HIV patients, 500 mg twice daily) interrupted every 6–12 months. child not recommended.

VALACICLOVIR:

Indications: Chickenpox, Herpes Genitalis, Herpes Labialis, Herpes Zoster, Recurrent Herpes Genitalis, and Suppression of Recurrent Herpes Simplex Infection.

Contraindications: Bone Marrow Transplant, Renal Transplant.

Dose and Administration: Herpes zoster, 1 g 3 times daily for 7 days. Herpes simplex, first episode, 500 mg twice daily for 5 days (longer if new lesions appear during treatment or if healing incomplete); recurrent infection, 500 mg twice daily for 5 days. Herpes simplex, suppression, 500 mg daily in 1–2 divided doses. Reduction of transmission of genital herpes, seek specialist advice, 500 mg once daily to be taken by the infected partner. Prevention of cytomegalovirus disease following renal transplantation (preferably starting within 72 hours of transplantation), 2 g 4 times daily usually for 90 days. child not recommended.

Cytomegalovirus infection

GANCICLOVIR:

Indications: CMV (cytomegalovirus) Retinitis in AIDS Patients, CMV Retinitis in Immunocompromised Patients, and Prevention of CMV Disease After Organ Transplant.

Contraindications: Lactating Mother, Severe Neutropenic Disorder, Severe Thrombocytopenia, Neutropenic Disorder, Renal Disease, Severe Anemia, And Thrombocytopenic Disorder.

Dose and Administration: By intravenous infusion, initially (induction) 5 mg/kg every 12 hours for 14–21 days for treatment or for 7–14 days for prevention; maintenance (for patients at risk of relapse of retinitis) 6 mg/kg daily on 5 days per week or 5 mg/kg daily until adequate recovery of immunity; if retinitis progresses initial induction treatment may be repeated.

VALGANCICLOVIR:

Indications: CMV Retinitis in AIDS Patients, Prevention of CMV Disease After Cardiac Transplantation, Prevention of CMV Disease After Kidney-Pancreas Transplantation, Prevention of CMV Disease After Kidney Transplantation. Contraindications: Aplastic Anemia, Lactating Mother, Severe Anemia, Severe Bone Marrow Depression, Severe Neutropenic Disorder, Severe Thrombocytopenia, Anemia, Neutropenic Disorder, Renal Disease, Thrombocytopenic Disorder.

Dose and Administration: CMV retinitis, induction, 900 mg twice daily for 21 days then 900 mg once daily; induction regimen may be repeated if retinitis progresses. Prevention of cytomegalovirus disease following solid organ transplantation (starting within 10 days of transplantation), 900 mg once daily for 100 days. child under 18 years not recommended.

Viral hepatitis

The management of uncomplicated acute viral hepatitis is largely symptomatic. Early treatment of acute hepatitis C with interferon alfa may reduce the risk of chronic infection. Hepatitis B and hepatitis C viruses are major causes of chronic hepatitis. For details on immunisation against hepatitis A and B infections.

ADEFOVIR DIPIVOXIL:

Indications: chronic hepatitis B infection with either compensated liver disease with evidence of viral replication, and histologically documented active liver inflammation and fibrosis or decompensated liver disease.

Contraindications: Lactating Mother, Lactic Acidosis, and Steatosis of Liver.

Dose and Administration: adult over 18 years, 10 mg once daily.

LAMIVUDINE:

Indications: Chronic Type B Viral Hepatitis, HIV Infection.

Contraindications: Acute Pancreatitis, Chronic Pancreatitis, Lactating Mother, Lactic Acidosis, and Steatosis of Liver.

Dose and Administration: Chronic hepatitis B infection with either compensated liver disease (with evidence of viral replication and histology of active liver inflammation or fibrosis), or decompensated liver disease, 100 mg daily; child 2–11 years, 3 mg/kg once daily (max. 100 mg daily); 12–17 years, adult dose.

ENTECAVIR:

Indications: chronic hepatitis B infection with compensated liver disease, evidence of viral replication, and histologically documented active liver inflammation or fibrosis.

Contraindications: Abnormal Hepatic Function Tests, Lactic Acidosis, Steatosis of Liver and breast-feeding.

Dose and Administration: adult over 18 years, not previously treated with nucleoside analogues, 500 micrograms once daily. adult over 18 years with lamivudine-resistant chronic hepatitis B, 1 mg once daily.

Influenza

Oseltamivir and zanamivir reduce replication of influenza A and B viruses by inhibiting viral neuraminidase. They are most effective for the treatment of influenza if started within a few hours of the onset of symptoms; they are licensed for use within 48 hours of the first symptoms.

OSELTAMIVIR:

Indications: Oseltamivir licensed for post-exposure prophylaxis of influenza when influenza is circulating in the community. Oseltamivir should be given within 48 hours of exposure to influenza. Oseltamivir also licensed for use in exceptional circumstances (e.g. when vaccination does not cover the infecting strain) to prevent influenza in an epidemic.

Contraindications: Severe Renal Disease, Delirium, Impaired Cognition, Suicidal Ideation.

Dose and Administration: Prevention of influenza, adult and adolescent over 13 years, 75 mg once daily for 10 days for post-exposure prophylaxis; for up to 6 weeks during an epidemic; child 1–13 years, body-weight under 15 kg, 30 mg once daily, body-weight 15–23 kg, 45 mg once daily, body-weight 23–40 kg, 60 mg once daily, body-weight over 40 kg, adult dose. Treatment of influenza, adult and adolescent over 13 years, 75 mg every 12 hours for 5 days; child 1–13 years, body-weight under 15 kg, 30 mg every 12 hours, body-weight 15–23 kg, 45 mg every 12 hours, body-weight 23–40 kg, 60 mg every 12 hours, body-weight over 40 kg, adult dose.

ZANAMIVIR:

Indications: Zanamivir licensed for post-exposure prophylaxis of influenza when influenza is circulating in the community. Zanamivir should be given within 36 hours of exposure to influenza. Zanamivir also licensed for use in exceptional circumstances (e.g. when vaccination does not cover the infecting strain) to prevent influenza in an epidemic.

Contraindications: Bronchospastic Pulmonary Disease, Chronic Obstructive Pulmonary Disease.

Dose and Administration: By inhalation of powder, post-exposure prophylaxis of influenza, adult and child over 5 years, 10 mg once daily for 10 days. Prevention of influenza during an epidemic, adult and child over 12 years, 10 mg once daily for up to 28 days. Treatment of influenza, adult and child over 5 years, 10 mg twice daily for 5 days.

Respiratory syncytial virus

PALIVIZUMAB:

Indications: monoclonal antibody licensed for preventing serious lower respiratory-tract disease caused by respiratory syncytial virus in children at high risk of the disease; it should be prescribed under specialist supervision and on the basis of the likelihood of hospitalisation.

Contraindications: Severe Coagulation Defects, Thrombocytopenic Disorder.

Dose and Administration: By intramuscular injection (preferably in anterolateral thigh), 15 mg/kg once a month during season of RSV risk (child undergoing cardiac bypass surgery, 15 mg/kg as soon as stable after surgery, then once a month during season of risk); injection volume over 1 mL should be divided between more than one site.

RIBAVIRIN:

Indications: in combination with peginterferon alfa or interferon alfa for chronic hepatitis C in patients without liver decompensation.

Contraindications: Autoimmune Hepatitis, Lactating Mother, Pregnancy, Sickle Cell Disease Anemia, and Thalassemia Anemia.

Dose and Administration: Chronic hepatitis C (in combination with interferon alfa or peginterferon alfa), adult over 18 years, body-weight under 75 kg, 400 mg in the morning and 600 mg in the evening; body-weight 75 kg and over, 600 mg twice daily.