What is the best course of management for a middle-aged adult patient with a history of cardiovascular disease, atrial fibrillation, and diabetes mellitus, presenting with a vesicular rash on the face, abdominal pain, and stable vital signs, diagnosed with Varicella Zoster, and currently on medications including Acyclovir (antiviral), Omep (Omeprazole) (proton pump inhibitor) IV for gastrointestinal protection, Mucosta (mucosal protective agent) TID, Diphenhydramine (antihistamine) 50mg IV q12, Digoxin (digitalis glycoside) 0.25mg, Rivaroxaban (anticoagulant), Diosmin+hesperidin (vasoprotective agent), Fenofibrate (fibrate), and Metformin (biguanide), with lab results showing mild leukopenia, mild anemia, hypercreatinemia, elevated liver enzymes, and hypernatremia, and a Pro BNP level of 1,100?

Management of Varicella Zoster in a Middle-Aged Adult with Multiple Comorbidities

Primary Diagnosis Confirmation

The admitting diagnosis of Varicella Zoster (herpes zoster/shingles) is appropriate given the vesicular rash on the face and abdominal pain, but the current acyclovir dosing of 800mg Q4 (every 4 hours) is critically inadequate and must be corrected immediately. 1

Key Diagnostic Considerations

• The vesicular rash with facial involvement and abdominal pain is consistent with herpes zoster, potentially with multi-dermatomal distribution 2, 3
• Facial involvement requires particular attention due to risk of ophthalmic complications and cranial nerve involvement 3
• The elevated liver enzymes (SGOT 131.78, SGPT 98.77) warrant close monitoring, as fulminant hepatic failure is a rare but serious complication of VZV in immunocompromised patients 4
• The patient's cardiovascular comorbidities (atrial fibrillation, diabetes mellitus) and medications suggest chronic disease burden that may affect immune function 2, 5

Critical Medication Error Requiring Immediate Correction

The current acyclovir regimen of 800mg Q4 is dangerously incorrect—the proper dosing for herpes zoster is 800mg every 4 hours, 5 times daily (not around the clock every 4 hours). 1

Correct Acyclovir Dosing

• Standard oral dosing for herpes zoster: 800mg orally 5 times daily (every 4 hours while awake) for 7-10 days 1
• Treatment must continue until all lesions have completely scabbed, not just for an arbitrary 7-day period 3
• The current "Q4" notation suggests dosing every 4 hours continuously (6 doses/day), which is incorrect per FDA labeling 1

Differential Diagnoses to Consider

Primary Differential

• Disseminated varicella zoster: Multi-dermatomal involvement (face and abdomen) raises concern for disseminated disease, which would require IV acyclovir 2, 3
• VZV hepatitis: Elevated transaminases (SGOT 131.78, SGPT 98.77) may represent visceral VZV involvement, a serious complication requiring escalation to IV therapy 2, 4
• Secondary bacterial superinfection: Monitor for signs of bacterial infection complicating the vesicular lesions 2

Other Considerations

• Drug-induced hepatotoxicity: Fenofibrate and metformin can cause hepatotoxicity, but the temporal relationship with VZV makes viral hepatitis more likely 4
• Zoster sine herpete with atypical presentation: Though less likely given visible rash 6

Immediate Management Algorithm

Step 1: Assess Disease Severity and Route of Administration

Evaluate for indications requiring IV acyclovir rather than oral therapy:

• Multi-dermatomal involvement (face AND abdomen suggests possible dissemination) 3
• Elevated liver enzymes suggesting possible visceral involvement 4
• Facial involvement with risk of ophthalmic complications 3
• Multiple cardiovascular comorbidities and diabetes may indicate relative immunosuppression 2, 5

If any of the following are present, switch to IV acyclovir 10 mg/kg every 8 hours: 3, 7

• Disseminated herpes zoster (multi-dermatomal, visceral involvement)
• Complicated facial zoster with suspected CNS involvement
• Elevated liver enzymes suggesting VZV hepatitis
• Evidence of immunocompromise beyond diabetes alone

If uncomplicated dermatomal disease, correct to proper oral dosing: 800mg orally 5 times daily 1

Step 2: Renal Function Assessment and Dose Adjustment

• Current creatinine is 72.10 μmol/L (approximately 0.81 mg/dL), suggesting normal renal function
• Calculate creatinine clearance to confirm no dose adjustment needed 1
• For creatinine clearance >25 mL/min: standard dosing of 800mg every 4 hours, 5 times daily 1
• Monitor renal function closely during IV acyclovir therapy if initiated, with dose adjustments as needed 3

Step 3: Address Medication Interactions and Complications

Critical medication review:

• Digoxin 0.25mg (listed as "25mg" but likely 0.25mg): Digoxin use in atrial fibrillation patients with diabetes is associated with increased all-cause mortality and cardiovascular death 8
• Rivaroxaban: Continue for stroke prevention in atrial fibrillation; efficacy and safety are similar in diabetic vs non-diabetic patients 9
• Hypokalemia (K 3.18): Correct potassium to >4.0 mEq/L, as hypokalemia increases digoxin toxicity risk 8
• Pro-BNP 1,100: Suggests heart failure, which is common in patients on digoxin 8

Step 4: Monitoring and Treatment Duration

Continue antiviral therapy until all lesions have completely scabbed—this is the key clinical endpoint, not an arbitrary 7-day duration 3

• Monitor for new lesion formation daily 3
• In immunocompromised patients, lesions may continue to develop for 7-14 days and heal more slowly 7
• If lesions fail to begin resolving within 7-10 days, suspect acyclovir resistance and obtain viral culture with susceptibility testing 3
• Monitor liver enzymes every 2-3 days given initial elevation 4
• Monitor renal function if on IV acyclovir 3

Step 5: Symptomatic Management

• Continue diphenhydramine 50mg IV q12 for pruritus 2
• Continue omeprazole IV and mucosta for GI protection, particularly important given abdominal pain 2
• Add NSAIDs or acetaminophen for acute pain management 6
• Keep skin well hydrated with emollients after lesions crust to avoid dryness and cracking 3
• Avoid topical corticosteroids on active vesicular lesions, as this can worsen infection and increase dissemination risk 3

Infection Control Measures

• Isolate patient from pregnant women, immunocompromised individuals, and those without varicella immunity until all lesions have crusted 3, 6
• Lesions are contagious to individuals who have not had chickenpox 3

Prevention of Future Episodes

After recovery from the current episode, strongly recommend the recombinant zoster vaccine (Shingrix) for prevention of future VZV reactivation 2, 3

• The vaccine reduces risk of future herpes zoster by over 90% 6
• Recommended for all adults aged 50 years and older, regardless of prior herpes zoster episodes 2, 3
• Two-dose series provides superior protection compared to live attenuated vaccine 2

Common Pitfalls to Avoid

• Do not discontinue antiviral therapy at exactly 7 days if lesions are still forming or have not completely scabbed 3
• Do not use topical antivirals—they are substantially less effective than systemic therapy 3
• Do not apply corticosteroid creams to active vesicular lesions, as this increases risk of dissemination 3
• Do not ignore elevated liver enzymes—VZV hepatitis can progress to fulminant hepatic failure in rare cases 4
• Monitor digoxin levels and consider discontinuation given association with increased mortality in AF patients with diabetes 8
• Correct hypokalemia before it worsens digoxin toxicity 8