Doxycycline 40 mg
Doxycycline
ALSO — ANTI-INFLAMMATORY DOSE DOXYCYCLINE
An oral tetracycline deliberately dosed under the antibacterial threshold, with a label that forbids using it for infection. The answer to every undosed antibiotic in this register.
The marker is a representative concentration from the cited records. The bar includes approved and compounded preparations recorded here. It is not a recommended dose, a minimum effective strength or a claim that other concentrations are untested. Evidence depends on the vehicle, indication and trial population.
The shaded band is the depth this molecule is understood to reach. Anything below it is out of scope, whatever the label says.
Mechanism
At 40 mg split into 30 mg immediate and 10 mg delayed release, plasma concentrations stay below those required to treat bacterial disease while retaining inhibition of matrix metalloproteinases and neutrophil chemotaxis.
HOUSE NOTES
- The limitations of use forbid treating bacterial infections, providing antibacterial prophylaxis or reducing organisms associated with any bacterial disease.
- In vivo studies at comparable exposure for up to eighteen months found no detectable long-term effect on the bacterial flora of the oral cavity, skin, intestinal tract and vagina.
- The patient counselling section warns that exceeding 40 mg increases the likelihood of bacteria developing resistance. More is not a stronger version of this drug.
- It does nothing for erythema, and the label says so three separate times.
- Sixteen weeks is the longest controlled duration in this register.
MEASURED ENDPOINTS
SUPPORTING RECORDS
Randomised, placebo-controlled, multi-centre Phase 3
N=251 · 16 WK · DOUBLE-BLIND
In vivo microbiological study at comparable drug exposure, oral cavity, skin, intestinal tract and vagina
N=0 · 78 WK · N/A
Layering
- Pregnancy and breastfeeding
- Any use as an antibiotic
- Doses above 40 mg
- Topical ivermectin
- Topical azelaic acid
- Daily sunscreen