The provider mistakenly prescribed levetiracetam (Keppra) instead of cephalexin (Keflex); the patient has taken Keppra for three days. Should Keppra be discontinued and the appropriate antibiotic started, and what is the recommended regimen?

Immediate Discontinuation of Keppra and Initiation of Appropriate Antibiotic Therapy

Keppra (levetiracetam) must be discontinued immediately, and the patient should be started on cephalexin (Keflex) for the intended bacterial infection. Three days of Keppra exposure in a patient without seizures poses unnecessary risks without therapeutic benefit.

Discontinuation of Keppra

Abrupt discontinuation is appropriate in this scenario because the patient does not have epilepsy and was never intended to receive an antiseizure medication 1. The FDA labeling warns that antiepileptic drugs should be withdrawn gradually to minimize increased seizure frequency, but this applies to patients with epilepsy who are being treated for seizures 1. In a patient without a seizure disorder who received the medication in error, there is no seizure threshold to protect, and the risk-benefit clearly favors immediate cessation.

Risks of Continued Keppra Exposure

• Behavioral and psychiatric effects: Keppra is associated with non-psychotic behavioral disorders (aggression, irritability) in 5-11.4% of patients, and mood disorders (depression, mood swings) in 6.7-12.7% of patients 1
• Somnolence and CNS depression: Occurs in 11.7% of patients and can impair daily functioning 1
• Rare but serious adverse effects: Including eosinophilia with fever, acute kidney injury, and drug hypersensitivity reactions have been reported 2, 3
• No therapeutic benefit: The patient has no indication for antiseizure medication, making any adverse effect unacceptable

Initiation of Appropriate Antibiotic Therapy

The specific antibiotic choice depends on the clinical indication that prompted the original Keflex prescription. However, cephalexin remains the appropriate first-line agent for most common community-acquired skin and soft tissue infections caused by methicillin-susceptible Staphylococcus aureus (MSSA) 4.

Cephalexin Dosing

For adults: 500 mg orally four times daily 4

For children: 25-50 mg/kg/day divided into 3-4 doses 4

Common Indications for Cephalexin

• Skin and soft tissue infections (SSTI): Cephalexin is the preferred oral agent for MSSA infections including impetigo, cellulitis, and uncomplicated abscesses 4
• Community-acquired pneumonia: For methicillin-susceptible Staphylococcus aureus pneumonia in children, oral cephalexin 75-100 mg/kg/day in 3-4 doses is preferred 4
• Prosthetic joint infections: Cephalexin 500 mg orally three to four times daily is used for chronic suppression of MSSA 4

Duration of Therapy

• Skin and soft tissue infections: Typically 7 days depending on clinical response 4
• Pneumonia: Duration varies by pathogen and severity, typically 5-10 days 4
• The patient has already lost 3 days of appropriate antibiotic therapy, so prompt initiation is critical

Clinical Monitoring

After discontinuing Keppra and starting cephalexin:

• No tapering schedule is needed for Keppra discontinuation in this non-epileptic patient 1
• Monitor for resolution of infection with appropriate antibiotic therapy
• Assess for any withdrawal symptoms from Keppra, though these are unlikely in a patient without epilepsy who received only 3 days of therapy
• Watch for cephalexin adverse effects: Generally mild, including gastrointestinal upset and rare hypersensitivity reactions 5, 6

Documentation and Error Prevention

This medication error highlights the importance of:

• Sound-alike medication awareness: Keppra/Keflex confusion is a known prescribing hazard
• Electronic prescribing systems: Can reduce but not eliminate such errors
• Patient education: Patients should be informed of the medication name and indication
• Pharmacy verification: Double-check mechanisms for sound-alike medications