Can a patient with persistent pruritus (itching) after two treatments with permethrin (permethrin) cream for scabies be retreated with permethrin cream and ivermectin (ivermectin)?

From the Guidelines

The patient can be treated again with permethrin cream and ivermectin for persistent scabies symptoms, considering retreatment 2 weeks after the initial treatment regimen as recommended by the guidelines 1. When considering retreatment, it's essential to assess the patient's response to the initial treatment and determine if live mites are still present.

• The guidelines suggest using an alternative regimen for those who do not respond initially to the recommended treatment 1.
• For retreatment, applying 5% permethrin cream from neck to toes, leaving it on for 8-14 hours before washing off, and repeating in 7-10 days can be effective 1.
• Oral ivermectin can be added at a dose of 200 mcg/kg (typically one dose, repeated in 7-10 days) to enhance treatment efficacy. It's crucial to note that persistent itching after treatment is common and may continue for 2-4 weeks even after successful treatment due to the ongoing immune response to dead mites and their products 1. To prevent reinfestation, it's essential to treat all household members and close contacts simultaneously and wash all bedding, clothing, and towels in hot water. If symptoms persist beyond 4-6 weeks despite proper treatment, consider alternative diagnoses or resistant scabies requiring dermatology consultation.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Adults and children ... ONE APPLICATION IS GENERALLY CURATIVE. Patients may experience persistent pruritus after treatment. This is rarely a sign of treatment failure and is not an indication for retreatment. Demonstrable living mites after 14 days indicate that retreatment is necessary. The patient can be treated again with permethrin cream if there are demonstrable living mites after 14 days, as indicated in the label. However, the label does not provide information about using ivermectin in combination with permethrin cream for retreatment 2.

• The label only mentions permethrin cream retreatment criteria.
• There is no information about using ivermectin with permethrin cream for scabies treatment in the provided label.

From the Research

Treatment Options for Scabies

• The patient has been treated twice with permethrin cream for scabies, but the itching continues, indicating a potential treatment failure 3.
• Permethrin 5% cream is considered a first-line therapy for scabies, but resistance to this agent has been reported in some cases 3.
• Ivermectin is another treatment option for scabies, which can be used orally or topically 4, 5.
• The efficacy of ivermectin compared to permethrin has been studied, with some studies showing similar cure rates for both treatments 5.
• A combination of permethrin and ivermectin can be used to treat otherwise intractable cases of scabies, including crusted scabies 3.

Considerations for Re-Treatment

• Re-treatment with permethrin or ivermectin may be necessary if the initial treatment fails 4, 6.
• The patient's treatment history and response to previous treatments should be taken into account when deciding on a re-treatment plan 3.
• Proper application of the treatment and simultaneous treatment of contact persons are crucial for effective treatment of scabies 3.
• Incomplete decontamination of furnishings and clothes can also contribute to treatment failure 3.

Safety and Efficacy of Permethrin and Ivermectin

• Permethrin 5% cream has been shown to be effective in treating scabies, with a cure rate of 70-85% after two applications 6.
• Ivermectin has also been shown to be effective, with a cure rate of 64.7-82.3% after two applications 4.
• Both permethrin and ivermectin have been reported to be safe, with mild adverse events occurring in a small percentage of cases 5, 7.