Doxycycline
Mechanism :
It is a long acting tetracycline group of antibiotics. It is preferred to other tetracyclines because of its milder adverse effects and longer action of duration. Though tetracyclines are not recommended in children below 8 years it is used in children above 8 years with chloroquine resistant malaria along with quinine. It also used to treat other infections like diarrhea and venereal disease.
Indication :
- Bacterial Infection
- Anthrax
- Chlamydia Infection
- Lyme’s Disease
- Malaria
- Brucellosis
- Rickettsial fevers
- Plague
- Tularaemia
- Severe acne vulgaris
- Cholera
Contraindications :
Hypersensitivity to drug/class/component
Pregnancy, Patient less than 8 years old.
Dosing :
<8 years:
Not recommended due to tooth discoloration and enamel hypoplasia.
>8 years
Bacterial infections, severe acne vulgaris, Cutaneous anthrax, Rickettsial fever, Malarial fever:
2.2 mg/kg PO/IV 12 hourly 7-10 days (Max dose: 100 mg/dose). In malaria: Use along with
quinine.
Chlamydia Infection, Gonococcal Infection, Non-Gonococcal urethritis, Proctitis, Epididymitis:
2-4 mg/kg/day PO divided 12 hourly x 7-10 days, Max dose: 100 mg/dose.
Lymphogranuloma venereum (adolescents), Lyme’s disease, Tularemia:
2-4 mg/kg/day PO divided 12 hourly x 21 days (for Lyme’s arthritis to give for 28 days), Max dose: 100 mg/dose.
Anthrax (inhalational, GI, oropharyngeal):
2.2 mg/kg PO 12 hourly x 60 days; Max dose: 100 mg/dose.
Malaria prophylaxis:
2.2 mg/kg PO once a day, Max: 100 mg/day. Start: 1-2 days before exposure and discontinue after 4 weeks after exposure.
Cholera:
7 mg/kg PO single dose; not to exceed 300 mg/dose or Day 1: 2 mg/kg PO twice daily and Day 2 and 3: 2 mg/kg OD, Max: 100 mg/dose.
Adverse Effect :
Tooth discoloration in children <8 years, hypersensitivity reaction, photosensitivity, skin reaction, pericarditis, hepatitis, vasculitis, nephrotoxicity, thrombocytopenia, pancreatitis, pseudotumor cerebri, neutropenia, hemolytic anemia, Jarisch-Herxheimer reaction (brucellosis or spirochetal infection use), fetal harm (in utero exposure), nausea, dyspepsia, arthralgia.
Interaction :
Anticoagulant Drugs: Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage.
Penicillin: Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines in conjunction with penicillin.
Antacids and Iron Preparations: Absorption of tetracyclines is impaired by antacids containing aluminium, calcium, or magnesium, bismuth subsalicylate, and iron-containing preparations.
Oral Contraceptives: Concurrent use of tetracycline may render oral contraceptives less effective.
Barbiturates and Anti-Epileptics: Barbiturates, carbamazepine, and phenytoin decrease the half-life of doxycycline.
Penthrane: The concurrent use of tetracycline and Penthrane® (methoxyflurane) has been reported to result in fatal renal toxicity.
Drug/Laboratory Test Interactions: False elevations of urinary catecholamines may occur due to interference with the fluorescence test.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function |
| <10 | Dose as in normal renal function |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in normal renal function |
| HD | Not dialysed. Dose as in normal renal function |
| HDF/High flux | Unknown dialysability. Dose as in normal renal function |
| CAV/VVHD | Not dialysed. Dose as in normal renal function |
Hepatic Dose :
Decrease dose in severe hepatic disease because hepatic excretion into bile may be delayed and elimination half-life extended.