Clinical beta

FMBM is currently in clinical beta. Content is for professional review/testing and must not replace local protocols, senior clinical judgment, or official prescribing references.

Drug Monograph

Doxycycline

Doxycycline

Tetracycline (PO, IV)

AtypicalTick-bornePOCA-MRSA

Indication

CAP atypical coverage β€’ Lyme β€’ rickettsia β€’ chlamydia β€’ acne β€’ MRSA SSTI oral

At a glance

INDICATIONS (CORE USE)

Atypical pneumonia, tick-borne illness, **CA-MRSA SSTI oral option**, malaria prophylaxis β€” **esophagitis** if pill sticks; **photosensitivity**.

ADULT DOSE (STANDARD)

100 mg PO q12h or 200 mg load then 100 mg daily (indication-specific)

MAX DOSE

200 mg/day typical adult (IV higher in severe β€” short course)

Route

PO, IV

PEDIATRIC DOSE

>8 years / weight-based β€” avoid teeth staining <8 years except short course when benefit > risk (Rocky Mountain spotted fever)

Do not miss

Must-not-miss safety points

Major warning

- **Pill esophagitis** β€” take upright + full glass water; avoid pre-sleep dosing - Photosensitivity rash - Intracranial hypertension rare - Not first-line for severe bacterial meningitis

Indications

USE IF: Atypical infection, tick-borne disease, chlamydia, some MRSA SSTI oral, malaria prophylaxis. AVOID IF: Pregnancy (relative), young children for prolonged courses, severe renal failure on high IV accumulations.

Primary

  • Community-acquired pneumonia with atypical coverage need (often combination)
  • Skin/soft tissue infection due to CA-MRSA when oral therapy appropriate
  • Tick-borne diseases (e.g., Rocky Mountain spotted fever, Lyme per stage)

Secondary

  • Chlamydia / urethritis / cervicitis regimens
  • Malaria chemoprophylaxis / treatment adjunct

Other

  • Acne / rosacea dermatology dosing lower

Dosing

STANDARD (ADULT PO)

100 mg PO q12h (many infections); 200 mg load day 1 some regimens

ADULT DOSE

100 mg PO BID; some infections 200 mg load; IV available severe GI

PEDIATRIC DOSE

>8 y: 2–4 mg/kg/day divided (max 200 mg/day) β€” RMSF etc.

MAX DOSE

IV accumulation in renal failure β€” caution high-dose prolonged IV

Practical Note

Take with food if GI upset (some absorption nuance β€” usually acceptable).

Warnings

Clinical warnings

  • C. diff any antibiotic
  • Benign intracranial hypertension

Adverse effects

  • nausea
  • esophagitis
  • photosensitivity
  • Candida

Contraindications

  • Hypersensitivity to tetracyclines

Drug interactions

  • Antacids / iron / multivitamins β€” ↓ absorption (separate 2–3 h)
  • Warfarin β€” INR

Special populations

Pediatrics

>8 years / weight-based β€” avoid teeth staining <8 years except short course when benefit > risk (Rocky Mountain spotted fever)

Pregnancy

Pregnancy: generally avoid (teeth/bone deposition).

Lactation

relative infant dose low but caution <1 month infant.

Renal impairment

Oral: no major adjust; IV high dose + severe renal impairment β€” monitor. **CrCl scaffold (FMBM β€” titrate to FDA/SFDA label + institutional pharmacy nomogram):** - **CrCl β‰₯50** β†’ standard dosing per agent (doxycycline often minimal renal adjustment) - **CrCl 10–50** β†’ **caution** some tetracyclines; verify label vs severe CKD - **CrCl <10** β†’ avoid or extreme caution (agent-dependent); minocycline β†’ severe **hepatic** impairment caution

Hepatic impairment

Avoid or reduce in severe hepatic failure for IV tetracyclines.

Elderly

Esophagitis risk β€” hydration, positioning.

Administration

PO upright + water; IV slow per compatibility.

Monitoring

  • Monitor: - IV or prolonged oral course β†’ **LFTs** per indication - Doxycycline / minocycline β†’ **photosensitivity** counseling + sun protection - LFTs if IV prolonged
  • Recheck: - Clinical CAP response 48–72h - No clinical improvement at 48–72h β†’ reassess diagnosis, resistance, source control, and drug interactions - If targets not met after reassessment of dose, organ function, and interactions β†’ escalate per protocol (DO NOT continue blindly)

Overdose / toxicity

Clinical Picture

**Life-threatening (first):** **acute liver failure** (rare massive); **esophageal perforation** (pill injury) β€” uncommon. **Secondary:** GI upset, IV phlebitis, chronic pigmentation.

Immediate Actions

Stop β†’ antiemetics; hydration; LFTs if hepatitis suspected

Antidote

No specific antidote; treat complications (e.g. anaphylaxis β†’ epinephrine per ACLS)

Decontamination

Recent large PO β†’ charcoal if window

Escalation

Intractable vomiting, esophageal perforation suspicion, acute liver failure β†’ **ICU** / surgery; **severe renal failure with toxicity β†’ consider HD** (agent-dependent clearance) β€” pharmacy consult

Clinical pearls

Common mistakes, resistance logic, and bedside traps

High-Yield Summary

Oral **MRSA cellulitis** tool + **atypicals** + **ticks**. **Water + upright** or esophagus pays price. Sunscreen.

Clinical pearls

Stewardship: don’t add doxy to every CAP automatically β€” severity + local atypical prevalence. IVβ†’PO early when eating. *Stewardship (all antimicrobials):* Empiric choice β†’ syndrome severity + **local antibiogram**; shortest effective course.

Stewardship & safety

  • Esophagitis prevention
  • Photosensitivity
  • Pregnancy avoid

Pharmacokinetics

Good tissue penetration; hepatic clearance; long half-life allows daily dosing some indications.

Mechanism of action

30S ribosome inhibition β€” bacteriostatic.

Common brand names

Saudi Arabia

Vibramycin, Doxycycline

Global

Doryx, (placeholder β€” verify local formulary)

Common trade names are curated examples only β€” formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

  • Empiric choice β†’ tie to syndrome, severity, and local antibiogram β€” not habit.
  • IV β†’ PO step-down when oral bioavailability and susceptibility allow.
  • Do not use antibiotics for uncomplicated viral illness β€” stewardship.

References

Saudi Arabia

  • SFDA (Saudi Food & Drug Authority)
  • Saudi National Formulary / MOH (where available)

International

  • WHO Model List of Essential Medicines (verify current edition)
  • US FDA or EU EMA product information (when national SmPC is unavailable)
  • Sanford Guide
  • IDSA / ESCMID (indication-specific)
  • Local antimicrobial stewardship / hospital formulary
  • FDA / SFDA / regional product labeling
  • Sanford Guide
  • IDSA / ESCMID (indication-specific)
  • Local antimicrobial stewardship / hospital formulary
  • FDA / SFDA / regional product labeling

Do not miss

  • Uncomplicated viral URI/bronchitis β†’ antibiotics rarely indicated
  • Narrow or stop when susceptibilities + clinical stability allow
  • Young child prolonged course β†’ dental staining.
  • RMSF β€” do not wait for labs to treat.
  • Esophagitis prevention
  • Photosensitivity
  • Pregnancy avoid