Hydroxychloroquine Use in Acute Infections
Established Indications
- The Centers for Disease Control and Prevention recommends treating acute Q fever with doxycycline alone (100 mg twice daily); hydroxychloroquine should not be used for acute Q fever 1
- The Centers for Disease Control and Prevention recommends combination therapy with doxycycline (100 mg twice daily) plus hydroxychloroquine (200 mg three times daily) for 18-24 months for chronic Q fever, depending on valve involvement 1
- Hydroxychloroquine alkalinizes the acidified phagosomal compartment, allowing doxycycline to achieve bactericidal activity against C. burnetii in chronic Q fever 1
COVID-19 Treatment
- The World Health Organization and the Centers for Disease Control and Prevention do not support hydroxychloroquine use for COVID-19 treatment or prophylaxis 2
- Initial in vitro studies showed antiviral activity against SARS-CoV-2, but this did not translate to clinical benefit 3, 4, 5
- Proposed mechanisms of hydroxychloroquine against SARS-CoV-2 included interference with ACE2 receptor binding and lysosomal protease activity 5, 6
Patient Management
- Patients with rheumatic diseases on chronic hydroxychloroquine therapy should continue their medication during acute infections, including COVID-19, due to the immunomodulatory effects and risk of disease flares 5, 6, 7
- The standard dosing for rheumatic diseases is 200-400 mg daily (maximum 5 mg/kg actual body weight to minimize retinal toxicity) 2, 7
Safety Monitoring
- A baseline ophthalmologic examination is required before starting hydroxychloroquine therapy, with annual screening after 5 years for low-risk patients 2, 1
- Check G6PD levels in men of African, Asian, or Middle Eastern origin before starting hydroxychloroquine to avoid hemolysis 2
- Dose adjustment is required for renal impairment (reduce by 25% if eGFR <30 mL/min/1.73 m²) 2
- Monitor for photosensitivity, especially when combined with doxycycline 1
Hydroxychloroquine and Paxlovid Interaction Guidelines
Drug-Drug Interaction Assessment
- There is no absolute contraindication to combining hydroxychloroquine with ritonavir-containing regimens based on available drug interaction data, according to The Lancet Gastroenterology and Hepatology 8
- Chloroquine and hydroxychloroquine are generally safe with COVID-19 therapies from a drug-drug interaction standpoint, as reported by The Lancet Gastroenterology and Hepatology 8
- Ritonavir in Paxlovid acts as a pharmacokinetic booster for nirmatrelvir, not as the primary antiviral, and hydroxychloroquine does not significantly interfere with this, as stated in The Lancet Gastroenterology and Hepatology 8
- No dose adjustment of hydroxychloroquine is required when co-administered with ritonavir-containing regimens, according to The Lancet Gastroenterology and Hepatology 8
Practical Management Algorithm
- No dose adjustment is needed specifically for the Paxlovid interaction, as reported by The Lancet Gastroenterology and Hepatology 8
- Renal-dosed Paxlovid (nirmatrelvir 150 mg/ritonavir 100 mg twice daily for eGFR 30-60 mL/min) does not require hydroxychloroquine adjustment, according to The Lancet Gastroenterology and Hepatology 8
- The lower ritonavir exposure in renal dosing further reduces any theoretical interaction risk, as stated in The Lancet Gastroenterology and Hepatology 8
Common Pitfalls to Avoid
- Hydroxychloroquine is not recommended for COVID-19 treatment or prophylaxis, as recommended by the Journal of the American Academy of Dermatology 9
- Abrupt discontinuation of DMARDs can lead to irreversible disease progression, as warned by Arthritis care & research 10
- If there were a true contraindication (which there is not), consultation with rheumatology would be essential before stopping, as advised by Annals of Oncology 11