Intravenous Doxycycline Dosing Recommendations
The recommended dose of intravenous doxycycline for adults is 100 mg every 12 hours, with an initial loading dose of 200 mg on the first day of treatment. 1
Adult Dosing Protocol
- Initial dose: 200 mg on first day (can be administered as a single dose or divided into two 100 mg infusions)
- Maintenance dose: 100-200 mg daily depending on infection severity
- Administration: Infuse slowly over 1-4 hours (minimum 1 hour for 100 mg)
- Duration: Continue IV therapy only until oral therapy becomes appropriate
Pediatric Dosing Protocol
- For severe infections (children <45 kg): 2.2 mg/kg every 12 hours
- For less severe infections (children >8 years, <45 kg): 4.4 mg/kg divided into two doses on day 1, followed by 2.2 mg/kg daily
- Children ≥45 kg: Use adult dosing (100 mg every 12 hours)
Special Considerations
- Rapid administration must be avoided to prevent adverse reactions
- IV therapy should be limited - transition to oral therapy as soon as clinically appropriate
- No dosage adjustment needed for patients with renal impairment
- Contraindications: Children under 8 years (except for specific serious infections like anthrax)
- Infusion preparation: Reconstitute with 10 mL of sterile water for injection (100 mg vial), then further dilute with 100-1000 mL of compatible IV solutions 1
Indication-Specific Dosing
- Inhalational anthrax: 100 mg IV twice daily for adults; 2.2 mg/kg twice daily for children <45 kg 2
- Primary/secondary syphilis: 300 mg daily for at least 10 days 1
- Pelvic inflammatory disease: 100 mg IV every 12 hours until clinical improvement, then transition to oral therapy to complete 14 days 2
Important Clinical Pearls
- Doxycycline is highly effective against many respiratory pathogens and can be cost-effective for hospitalized patients with community-acquired pneumonia 3
- Unlike other tetracyclines, doxycycline does not accumulate in patients with renal insufficiency and does not require dosage adjustment 4
- Because of doxycycline's excellent bioavailability, transition to oral therapy (100 mg twice daily) should occur as soon as clinically feasible 1
- When treating meningitis, be aware that doxycycline has suboptimal CNS penetration 2
- For MRSA infections requiring IV therapy, vancomycin is generally preferred over doxycycline 5
Monitoring and Adverse Effects
- Monitor for thrombophlebitis with prolonged IV administration
- Watch for GI side effects (nausea, vomiting, diarrhea)
- Avoid in pregnancy and children under 8 years when possible
- Separate administration from products containing calcium, iron, magnesium or sodium bicarbonate by at least 2 hours
By following these dosing recommendations and clinical considerations, you can optimize the use of intravenous doxycycline therapy while minimizing potential adverse effects.