Simplovir5% w/w

Simplovir 5% w/w intravenous (IV) infusion is a synthetic nucleoside analogue antiviral used to treat serious infections caused by the Herpes simplex virus (HSV) and Varicella zoster virus (VZV). It is administered under close medical supervision, usually in a hospital setting, for the following conditions:

• Acute clinical manifestations of Herpes simplex virus infection in immunocompromised patients
• Severe primary or non-primary genital herpes in patients with a normal immune system
• Varicella zoster virus (chickenpox) infection in immunocompromised patients
• Herpes zoster (shingles) in immunocompetent patients presenting with severe acute local or systemic symptoms
• Herpes simplex encephalitis, a serious viral infection of the brain

Simplovir 5% w/w Injection is reserved for severe or complicated herpesvirus infections that require rapid systemic drug levels not achievable with oral therapy. It does not cure herpes infections but significantly reduces the severity, duration, and complications of an outbreak.

Always take medicines strictly according to a registered physician's advice.

Antiviral agent used for the treatment of Herpes simplex and Varicella-zoster virus infections.

Simplovir 5% w/w is a guanosine nucleoside analogue with selective antiviral activity against Herpes simplex virus (Type 1 and 2) and Varicella zoster virus. Its mechanism of action depends on intracellular activation within virus-infected cells:

• Viral thymidine kinase converts Simplovir 5% w/w into Simplovir 5% w/w Monophosphate — a step that occurs far more efficiently in infected cells than in normal cells, giving the drug its selectivity
• Cellular guanylate kinase further converts the monophosphate to Simplovir 5% w/w Diphosphate
• Various cellular enzymes then convert it to Simplovir 5% w/w Triphosphate, the pharmacologically active form

Simplovir 5% w/w Triphosphate inhibits viral DNA polymerase and gets incorporated into the growing viral DNA chain, causing chain termination. This halts viral DNA synthesis and replication, while sparing uninfected host cells due to the virus-dependent activation pathway.

Simplovir 5% w/w Injection is intended strictly for intravenous infusion and must never be given by intramuscular, subcutaneous, or oral route.

Reconstitution

Dilution for Infusion

After reconstitution, the required dose should be further diluted in at least 50–100 mL of infusion fluid before administration:

• A maximum of 250 mg Simplovir 5% w/w may be added to 50 mL of infusion solution
• A maximum of 500 mg Simplovir 5% w/w may be added to 100 mL of infusion solution
• Final concentration should not exceed 0.5% w/v
• Shake the mixture thoroughly after adding Simplovir 5% w/w to the infusion fluid

Compatible Infusion Fluids

When diluted to a concentration of 0.5% w/v or less, Simplovir 5% w/w Infusion is compatible with the following fluids and remains stable for up to 12 hours at room temperature (below 25°C):

• Sodium Chloride Intravenous Infusion BP (0.45% and 0.9% w/v)
• Sodium Chloride (0.18% w/v) with Glucose (4% w/v) Intravenous Infusion
• Sodium Chloride (0.45% w/v) with Glucose (2.5% w/v) Intravenous Infusion
• Compound Sodium Lactate Intravenous Infusion BP (Hartmann's Solution)

Important Administration Notes

• The infusion must be given slowly over at least one hour to prevent renal tubular damage
• Contains no preservative — reconstitute and dilute immediately before use and discard any unused solution
• Do not refrigerate the reconstituted or diluted solution, as this may cause precipitation

Simplovir 5% w/w may interact with certain medications, altering its clearance or increasing the risk of adverse effects:

• Probenecid: Co-administration increases mean Simplovir 5% w/w half-life and area under the concentration-time curve, while reducing urinary excretion and renal clearance
• Diuretics (in patients over 60 years): Concurrent use significantly increases plasma Simplovir 5% w/w levels
• Nephrotoxic drugs (e.g., aminoglycosides, cisplatin, amphotericin B): May increase the risk of renal impairment when used with Simplovir 5% w/w
• Other nucleoside analogues (e.g., ganciclovir): Concomitant use is generally avoided due to overlapping toxicity affecting DNA synthesis

Inform your physician about all medications, supplements, and herbal products in use before starting Simplovir 5% w/w Injection therapy.

Simplovir 5% w/w Injection is generally well tolerated when administered correctly, but some patients may experience adverse effects, particularly with rapid infusion, dehydration, or pre-existing renal/neurological conditions.

Common Side Effects

• Nausea and vomiting
• Phlebitis or inflammation at the injection site
• Pruritus (itching), urticaria (hives), and skin rashes
• Reversible increases in liver enzymes
• Increases in blood urea and serum creatinine

Less Common but Serious Side Effects

• Lethargy and obtundation (reduced alertness)
• Tremors, confusion, hallucinations, and agitation
• Somnolence (excessive drowsiness) and psychosis
• Convulsions and coma (typically at high doses or in renal impairment)

Local inflammatory reactions and tissue irritation may occur if the infusion inadvertently leaks into surrounding tissue outside the vein (extravasation). Report any unusual neurological or allergic symptoms to your doctor immediately.

Simplovir 5% w/w Injection falls under Pregnancy Category B. Adequate and well-controlled studies in pregnant women are not available. It should be used during pregnancy only if the potential benefit to the mother clearly justifies the potential risk to the fetus.

Simplovir 5% w/w is excreted in breast milk. It should be given to breastfeeding mothers only when the benefits outweigh potential risks to the nursing infant. There is currently no clinical data regarding the effect of Simplovir 5% w/w on human fertility.

• For intravenous infusion only — must never be given by mouth, intramuscularly, or subcutaneously
• The reconstituted solution has a pH of approximately 11.0 and can cause tissue damage if administered incorrectly
• Must be infused slowly over at least one hour to avoid renal tubular damage; never give as a rapid bolus injection
• Adequate hydration must be maintained before and during infusion, as maximum urinary drug concentration occurs within the first few hours
• Concomitant use of other nephrotoxic drugs, pre-existing renal disease, or dehydration increases the risk of renal impairment
• Use with caution in patients with neurological abnormalities, significant hypoxia, or serious renal, hepatic, or electrolyte disturbances, as Simplovir 5% w/w has been associated with reversible encephalopathic changes

Overdosage with intravenous Simplovir 5% w/w has resulted in elevated serum creatinine, elevated blood urea nitrogen, and subsequent acute renal failure. Neurological effects such as confusion, hallucinations, agitation, seizures, and coma have also been reported in association with overdose.

Management is primarily supportive. Adequate hydration is essential to reduce the risk of crystal formation in the renal tubules. Hemodialysis significantly enhances the removal of Simplovir 5% w/w from the bloodstream and may be considered in managing severe overdose.

• Store at 15°C to 25°C (room temperature)
• Protect from light and moisture
• Do not refrigerate reconstituted or diluted solutions
• Keep out of the reach and sight of children

Pediatric Use

In children aged 1–12 years, dosing should be calculated based on body surface area:

• Herpes simplex infections (excluding encephalitis) or Varicella zoster infections: 250 mg/m² (equivalent to 5 mg/kg in adults)
• Immunocompromised children with Varicella zoster infection or Herpes simplex encephalitis: 500 mg/m² (equivalent to 10 mg/kg in adults)

Children with impaired renal function require an appropriately adjusted dose based on the severity of impairment.

Geriatric Use

Specific clinical data in elderly patients is limited. As creatinine clearance often declines with age, special attention should be given to dose reduction, and elderly patients should be monitored closely for renal and neurological side effects.

Renal Impairment