Doxycycline hyclate is a first-line human pharmaceutical for an unusually broad spectrum of indications -- from community-acquired pneumonia and chlamydia to malaria prophylaxis, Lyme disease, and anthrax post-exposure. Its safety in renal impairment and excellent oral bioavailability make it the tetracycline of choice in human clinical practice worldwide.
Quick Facts
| CAS Number | 24390-14-5 |
|---|---|
| Molecular Formula | C22H24N2O8 · HCl |
| Molecular Weight | 526.97 |
| HS Code | 2941302000 |
| Pharmacopoeia | BP/EP/CEP |
| Category | Pharmaceutical API |
| Packaging | 25 KG/DRUM |
Product Story
Doxycycline was discovered in 1967 by a team led by Charlie Stephens at Pfizer Laboratories, who set out to create a semi-synthetic tetracycline with superior pharmacokinetic properties. Building on the tetracycline scaffold developed by Lloyd Conover in the 1950s, Stephens' team chemically modified oxytetracycline to produce 6-deoxy-5-hydroxytetracycline — doxycycline. The compound was patented and approved for clinical use in 1967, launching under the brand name Vibramycin.
Doxycycline works by binding to the 30S ribosomal subunit, blocking aminoacyl-tRNA attachment and inhibiting bacterial protein synthesis. Its bacteriostatic mechanism is shared with the tetracycline class, but doxycycline's distinguishing features are its high lipophilicity and extended half-life (18-22 hours). These properties allow once or twice-daily dosing, excellent tissue penetration into the lungs, prostate, and CNS, and reliable oral absorption even with food — advantages that older tetracyclines like oxytetracycline lack.
Doxycycline's key clinical advantage is its safety in patients with renal impairment. Unlike tetracycline and oxytetracycline, which are primarily excreted renally and accumulate dangerously in kidney failure, doxycycline is eliminated via the gastrointestinal tract. This makes it the tetracycline of choice in patients with any degree of renal dysfunction. It is also the recommended first-line treatment for an unusually wide range of conditions: community-acquired pneumonia, chlamydia, early Lyme disease, rickettsial infections, malaria prophylaxis, leptospirosis, and anthrax post-exposure prophylaxis.
As of mid-2026, the global doxycycline hyclate API market is valued at over $500 million annually, driven by growing demand in respiratory infection treatment, malaria chemoprophylaxis, and rosacea/acne management. China is the dominant manufacturing hub, with CEP-certified API commanding a significant premium over standard-grade material. The doxycycline supply chain is sensitive to regional manufacturing disruptions — as evidenced during the 2022-2023 global shortage — making supplier diversification and reliable CEP-grade sources strategic priorities for pharmaceutical manufacturers.
Quality Specifications
| Purity (HPLC) | ≥ 95.0% and ≤ 102.0% (anhydrous basis), per BP/EP monograph |
|---|---|
| Related Substances | 4-Epidoxycycline ≤ 0.5%; 6-Epidoxycycline ≤ 0.5%; Total impurities ≤ 2.0% (EP) |
| Residual Solvents | Compliant with ICH Q3C; ethanol ≤ 5,000 ppm |
| Heavy Metals | ≤ 20 ppm |
| GMP Status | Manufactured under ICH Q7 GMP conditions |
| Key Tests | pH 2.0-3.0 (1% aqueous solution); specific optical rotation -105° to -120°; loss on drying ≤ 3.0% |
Pharmaceutical Applications
- Respiratory Tract Infections: Community-acquired pneumonia, atypical pneumonia (Mycoplasma, Chlamydia, Legionella), and acute bacterial sinusitis.
- Sexually Transmitted Infections: First-line for Chlamydia trachomatis (100 mg BID for 7 days) and non-gonococcal urethritis. Alternative for syphilis in penicillin-allergic patients.
- Dermatology: Anti-inflammatory dose (40 mg/day modified-release) for acne vulgaris and rosacea. Lower than antimicrobial dose, minimizing resistance selection pressure.
- Malaria Prophylaxis: CDC-recommended for travelers to chloroquine-resistant regions. 100 mg daily starting 1-2 days before travel through 4 weeks after return.
- Lyme Disease: First-line treatment for early localized and early disseminated Lyme disease. Also effective for human granulocytic anaplasmosis.
- Anthrax & Biodefense: Post-exposure prophylaxis and treatment of cutaneous and inhalational anthrax. Stockpiled by national strategic reserves globally.
Sourcing Doxycycline Hyclate: Key Checks
Documentation
Request CoA with HPLC assay, epimer impurity profile (4-epidoxycycline, 6-epidoxycycline), and residual solvent data. For EU markets, CEP is the preferred regulatory pathway. Batch-specific stability data and photostability assessment are also recommended.
Red Flags
Elevated epimer content (4-epidoxycycline or 6-epidoxycycline exceeding pharmacopoeia limits), brownish discoloration (photodegradation), prices significantly below market average, and reluctance to provide impurity profile data.
Packaging & Logistics
Standard: 25 KG/DRUM, aluminum foil-lined to protect from light. Doxycycline is photolabile and hygroscopic — verify light-resistant packaging and desiccant use. Standard lead time 4-8 weeks from major Chinese ports.
Market Context
Global doxycycline hyclate API market exceeds $500M/year with strong growth in respiratory and STI indications. China dominates production. The 2022-2023 global shortage highlighted the strategic value of diversified, CEP-certified supply. DrugBank reference