Name of the Anti-Viral Drugs
- Acyclovir
- Penciclovir
1.Acyclovir
| Acyclovir |
| Availability: injectable solution :50mg/mL ; injection, lyophilized powder for reconstitution 500mg/vial ,1000mg/vial oral suspension 200mg/5mL; Tablet 400mg ,800mg; Capsule ,200mg |
| Indication & dosage Genital Herpes Initial treatment: 200 mg PO q4hr while awake (5 times daily) for 10 days or 400 mg PO q8hr for 7-10 days Intermittent treatment for recurrence: 200 mg PO q4hr while awake (5 times daily) for 5 days; initiate at earliest sign or symptom of recurrence Chronic suppression for recurrence: 400 mg PO q12hr for up to 12 months; alternatively, 200 mg 3-5 times daily |
| Herpes Simplex Virus Encephalitis 10-15 mg/kg IV q8hr for 10 days; up to 14-21 days reported |
| Mucocutaneous Herpes Simplex Virus Infection Treatment in immunocompromised patients IV: 5 mg/kg q8hr for 7 days; dosing up to 14 days reported PO (off-label): 400 mg q4hr while awake (5 times daily) for 7 days |
| Herpes Zoster (Shingles) Acute treatment: 800 mg PO q4hr while awake (5 times daily) for 7-10 days Immunocompromised patients 10 mg/kg IV q8hr for 7 days CrCl 25-50 mL/min: Full recommended IV dose q12hr CrCl 10-25 mL/min: Full recommended IV dose once daily CrCl 0-10 mL/min: 50% of recommended IV dose once daily |
| Varicella Zoster (Chickenpox) >40 kg (immunocompetent): 800 mg PO q6hr for 5 days Immunocompromised patients: 10-15 mg/kg IV q8hr for 7-10 days |
Mechanism of Action:
Interferes with DNA polymerase to inhibit DNA replication via chain termination
Contraindications:
Hypersensitivity.
Contraindicated with allergy to acyclovir, seizures, CHF, renal disease, lactation.
Use cautiously with pregnancy.
Administration:
- For limited mucocutaneous lesions, acyclovir administration can be via the oral route. In cases with disseminated, visceral, or CNS involvement, the acyclovir administration should be intravenous.
- When taken orally, acyclovir may be taken with or without food 2 to 5 times a day for 5 to 10 days and up to 12 months to prevent outbreaks of genital herpes.
- Intravenous administration should be done via IV infusion only, over 1 hour, at a constant rate to prevent renal damage. Medication should be in a diluted D5W solution or 0.9% NaCl to a final concentration of less than or equal to 7 mg/mL.
Metabolism & Elimination
Absorption: po ,15-30%
Peak serum time: 1.5-2 hr (po); 1 hr (IV)
Metabolism: by liver
Half-life: 4 hr (neonates); 2-3hr (children 1-12 years )3 hr (adult)
Excretion: urine (62-90% as unchanged drug)
Precautions:
renal failure/impairment, immunocompromised host, potential risk of thrombotic thrombocytopenic purpura (TTP), and hemolytic uremic syndrome (HUS).
Adverse Reactions/Side Effects
CNS: SEIZURES, dizziness, headache, hallucinations, trembling.
GI: diarrhea, nausea, vomiting, elevated liver enzymes, hyperbilirubinemia, abdominal pain, anorexia.
GU: RENAL FAILURE, crystalluria, hematuria, renal pain.
Derm: acne, hives, skin rashes, unusual sweating, STEVENS-JOHNSON SYNDROME.
Endo: changes in menstrual cycle.
Hemat: THROMBOTIC THROMBOCYTOPENIC PURPURA/HEMOLYTIC UREMIC SYNDROME (HIGH DOSES IN IMMUNOSUPPRESSED PATIENTS).
Local: pain, phlebitis, local irritation.
MS: joint pain.
Misc: polydipsia.
PATIENT TEACHING
Patients should be monitored for adverse effects such as malaise, inflammation or phlebitis at the infusion site, nausea, vomiting, rash (including Steven-Johnson syndrome), transaminitis, nausea, vomiting, diarrhea, headache, abdominal pain, aggression/confusion, agitation, alopecia, anaphylaxis, anemia, angioedema, anorexia, ataxia, coma, disseminated intravascular coagulation (DIC), dizziness and fatigue.
Patient teaching
Systemic administration
- Complete the full course of oral therapy, and do not exceed the prescribed dose.
- Oral acyclovir is not a cure for your disease but should make you feel better.
- Avoid sexual intercourse while visible lesions are present.
- You may experience these side effects: Nausea, vomiting, loss of appetite, diarrhea; headache, dizziness.
- Report difficulty urinating, rash, increased severity or frequency of recurrences.
Topical administration
- Wear rubber gloves or finger cots when applying the drug to prevent autoinoculation of other sites and transmission to others.
- This drug does not cure the disease; application during symptom-free periods will not prevent recurrences.
- Avoid sexual intercourse while visible lesions are present.
- This drug may cause burning, stinging, itching, rash; notify your physician if these are pronounced.
Nursing Considerations
Assessment
- History: Allergy to acyclovir, seizures, CHF, renal disease, lactation, pregnancy
- Physical: Skin color, lesions; orientation; BP, P, auscultation, perfusion, edema; R, adventitious sounds; urinary output; BUN, creatinine clearance
Interventions
Systemic administration
- Ensure that the patient is well hydrated.
Topical administration
- Start treatment as soon as possible after onset of signs and symptoms.
- Wear a rubber glove or finger cot when applying drug.
2.Penciclovir
| Penciclovir |
| Availability: Cream 1% |
| Indication & dosage Acute herpes zoster infections (shingles). Treatment/suppression of recurrent herpes genitalis in immunocompetent patients. Treatment of recurrent mucocutaneous herpes simplex virus (HSV) infection in HIV-infected patients. |
| Mechanism of Action : Penciclovir is converted to the pharmacologically active triphosphate metabolite, which has in vitro and in vivo inhibitory activity against various Herpesviridae, including herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), and Epstein-Barr virus (EBV) |
| Contraindications : Hypersensitivity. |
| Administration : Ganciclovir must be administered by intravenous infusion over 1 hour at a concentration not exceeding 10 mg/mL. Do not administer by rapid or bolus intravenous injection because the resulting excessive plasma levels may increase the toxicity of ganciclovir. Do not administer by intramuscular or subcutaneous injection because this may result in severe tissue irritation due to the high pH (~11) of ganciclovir solutions |
| Metabolism & Elimination Absorption: Following absorption, famciclovir is rapidly converted in the intestinal wall to penciclovir, the active compound. Distribution: Unknown. Metabolism and Excretion: Penciclovir is mostly excreted by the kidneys. Half-life: Penciclovir—2.1–3 hr (increased in renal impairment). |
| Precautions: Patients with impaired renal function (increased dosage interval/decreased dose recommended if CCr <40–60 mL/min); Geri: Geriatric patients (because of age-related decrease in renal function); OB/Pedi: Pregnancy, lactation, or children <18 yr (safety not established). |
Adverse Reactions/Side Effects
CNS: headache, dizziness, fatigue.
GI: diarrhea, nausea, vomiting.
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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