Doxycycline, a second-generation tetracycline antibiotic, has been a cornerstone of antimicrobial therapy since its introduction in the 1960s. Available in various formulations, including oral tablets, capsules, and injectable solutions, its powder form-often used for compounding, veterinary applications, and research-offers unique advantages in flexibility and bioavailability.
| Product Name | Doxycycline Powder | Doxycycline Tablets | Doxycycline Injection | Doxycycline Capsules | Doxycycline Paste | Doxycycline Drops | |
| Product Type | Powder | Tablet | Injection | Capsules | Paste | Drops | |
| Product Purity | >98% | >98% | >98% | >98% | >98% | >98% | |
| Product Specifications | 10g;100g;1kg | Customizable | Customizable | Customizable | Customizable | Customizable | |
| Product Form | Organic synthesis | Customizable | Customizable | Customizable | Customizable | Customizable | |
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| Certificate of Analysis | ||
| Compound name | Doxycycline | |
| CAS No. | 564-25-0 | |
| Quantity | 30kg | |
| Manufacturer | Shaanxi BLOOM TECH Co., Ltd | |
| Lot No. | 20250625012 | |
| MFG | Jun.28th2025 | |
| EXP | Jun.30th2028 | |
| Structure |
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| Item | Enterprise standard | Analysis result |
| Appearance | Light yellow to brown | Conformed |
| Water content | ≤5.0% | 0.12% |
| Heavy Metals | Pb≤0.5ppm | N.D. |
| As≤0.5ppm | N.D. | |
| Hg≤0.5ppm | N.D. | |
| Cd≤0.5ppm | N.D. | |
| Purity (HPLC) | >98% | 99.26% |
| Single impurity | <0.8% | 0.16% |
| Total microbial count | ≤750cfu/g | 30 |
| E. Coli | ≤2MPN/g | N.D. |
| Salmonella | N.D. | N.D. |
| Ethanol (by GC) | ≤5000ppm | 100ppm |
| Storage | -80°C, 2 years; -20°C, 1 year (Sealed storage, away from moisture) | |
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| Shaanxi Chuzhan is a technology enterprise specializing in the research and development, production of chemicals and equipment customization services, providing OEM/ODM full-chain solutions. We offer flexible full-process customized services, from formula research and development to equipment selection, all can be deeply adapted according to customer requirements. Support full-cycle technical collaboration from small-scale trials, medium-scale trials to large-scale production, equipped with a professional engineering team to provide process optimization suggestions, and can customize packaging labels according to the brand requirements of customers. | ||
Mechanism of Action
Doxycycline exerts its primary effects through two distinct mechanisms:
Antibacterial Activity
Ribosomal Inhibition: Doxycycline binds to the 30S subunit of bacterial ribosomes, blocking the attachment of aminoacyl-tRNA and disrupting protein synthesis. This bacteriostatic action inhibits the growth of Gram-positive (e.g., Staphylococcus aureus, Streptococcus pneumoniae) and Gram-negative bacteria (e.g., Escherichia coli, Haemophilus influenzae), as well as atypical pathogens like Chlamydia trachomatis and Mycoplasma pneumoniae.
Biofilm Disruption: Studies suggest doxycycline may weaken bacterial biofilms, enhancing the efficacy of other antibiotics in chronic infections like cystic fibrosis-associated lung infections.
Anti-Inflammatory and Immunomodulatory Effects
Matrix Metalloproteinase (MMP) Inhibition: Doxycycline suppresses MMPs, enzymes implicated in tissue degradation and inflammation. This property is leveraged in treating periodontitis, rosacea, and rheumatoid arthritis.
Cytokine Modulation: Low-dose doxycycline reduces pro-inflammatory cytokines (e.g., TNF-α, IL-6), making it useful in non-infectious inflammatory conditions.
Chemical and Pharmacological Properties
Chemical Structure
Doxycycline is a semi-synthetic tetracycline with the molecular formula C₂₂H₂₄N₂O₈ and a molecular weight of 462.44 g/mol. Its structure consists of a four-ring naphthacene core with functional groups at positions 4, 5, 6, and 7, including a dimethylamino group at C4, which enhances its lipophilicity and tissue penetration.
Mechanism of Antibacterial Action
Doxycycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex. This action is bacteriostatic (halts bacterial growth) rather than bactericidal (kills bacteria), making it effective against a wide range of microorganisms, including:
1) Gram-positive bacteria: Staphylococcus aureus, Streptococcus pneumoniae, Listeria monocytogenes.
2) Gram-negative bacteria: Escherichia coli, Haemophilus influenzae, Neisseria gonorrhoeae.
3) Atypical pathogens: Mycoplasma pneumoniae, Chlamydia trachomatis, Legionella pneumophila.
4) Rickettsiae: Rickettsia rickettsii (Rocky Mountain spotted fever).
5) Spirochetes: Borrelia burgdorferi (Lyme disease), Treponema pallidum (syphilis).
Anti-Inflammatory and Immunomodulatory Effects
Beyond its antimicrobial properties, doxycycline exerts anti-inflammatory and immunomodulatory effects by:
Inhibiting matrix metalloproteinases (MMPs), enzymes involved in tissue degradation (e.g., in periodontitis and arthritis).
Suppressing pro-inflammatory cytokines (e.g., IL-6, TNF-α) in conditions like rosacea and rheumatoid arthritis.
Reducing oxidative stress by scavenging free radicals.
Pharmacokinetics of Doxycycline Powder
When reconstituted, doxycycline powder demonstrates favorable pharmacokinetics:
Absorption: ~90–100% bioavailability when taken orally with water; unaffected by food (unlike older tetracyclines).
Distribution: Widely distributed in tissues, including cerebrospinal fluid (CSF), synovial fluid, and prostate.
Half-life: 16–22 hours, allowing once-daily dosing.
Metabolism: Minimal hepatic metabolism; excreted primarily unchanged in feces (40%) and urine (20–30%).
Interaction between doxycycline and hepatic enzyme inducers
Interaction mechanism
The metabolism of doxycycline in the body primarily relies on the hepatic cytochrome P450 enzyme system (CYP450), especially CYP3A4 and CYP2C8. These enzymes convert doxycycline into inactive or less active metabolites through oxidation, hydroxylation, and other reactions, which are ultimately excreted via bile and urine. Hepatic enzyme inducers (such as phenobarbital, phenytoin, carbamazepine, and rifampin) can accelerate the metabolism of doxycycline through the following mechanisms:
Enhanced enzyme activity: Hepatic drug enzyme inducers directly activate the gene expression of CYP450 enzymes, increasing the synthesis of the enzymes. For example, phenytoin can increase CYP3A4 activity by 2-3 times, resulting in a reduction of doxycycline's half-life from 14-22 hours to approximately 7 hours.
Changes in enzyme stability: Certain inducers (such as rifampin) enhance the stability of CYP450 enzymes by altering the intracellular environment of hepatocytes, thereby prolonging their action time.
Competitive binding: The inducer may occupy the active site of CYP450 enzyme, indirectly promoting the metabolic transformation of doxycycline.
Clinical impact
The accelerating effect of hepatic enzyme inducers on the metabolism of doxycycline directly leads to a decrease in its plasma concentration, which in turn causes the following clinical issues:
Reduced antibacterial efficacy: In the treatment of respiratory tract infections, the plasma concentration of doxycycline can be reduced by more than 50% in patients treated with phenytoin, leading to a decrease in bacterial clearance rate and prolongation of the disease course. For example, a study in patients with chronic bronchitis showed that after combination therapy with phenytoin, the minimum inhibitory concentration (MIC) value of doxycycline against Streptococcus pneumoniae increased by 2 times, and the treatment failure rate increased from 12% to 34%.
Increased risk of drug resistance: Insufficient plasma drug concentration may induce bacterial resistance. In the treatment of syphilis, if the plasma concentration of doxycycline is below 0.5 μg/mL, the clearance rate of spirochetes significantly decreases, which is prone to cause serofast (persistent positive serological response).
Imbalance in adverse reaction risks: To compensate for insufficient efficacy, clinicians may be forced to increase the dosage of doxycycline, which can lead to gastrointestinal reactions (such as nausea and vomiting), photosensitivity reactions (such as sunburn-like rash), and hepatotoxicity (such as elevated transaminases).
Clinical Applications
Infectious Diseases
1) Respiratory Tract Infections
Community-acquired pneumonia (CAP): Effective against Mycoplasma, Chlamydophila, and Legionella.
Bronchitis: Alternative to beta-lactams in penicillin-allergic patients.
Tuberculosis: Used in multidrug-resistant (MDR-TB) regimens.
2) Skin and Soft Tissue Infections
Acne vulgaris: Reduces Propionibacterium acnes colonization and inflammation.
Cellulitis: Effective against Staphylococcus and Streptococcus species.
Leprosy: First-line treatment for paucibacillary and multibacillary forms.
3) Sexually Transmitted Infections (STIs)
Chlamydia trachomatis: Preferred treatment for uncomplicated genital infections (100 mg twice daily for 7 days).
Gonorrhea: Used in combination with ceftriaxone due to rising resistance.
Syphilis: Alternative in penicillin-allergic patients (though less effective than benzathine penicillin).
4) Vector-Borne Diseases
Lyme disease: Early localized or disseminated infection (100 mg twice daily for 10–21 days).
Malaria prophylaxis: Effective against Plasmodium falciparum in chloroquine-resistant areas (100 mg daily starting 1–2 days before travel).
Babesiosis: Used with clindamycin for severe cases.
Non-Infectious Conditions
1) Periodontal Disease
Subantimicrobial-dose doxycycline (20 mg twice daily) inhibits MMPs, reducing periodontal pocket depth and bleeding.
2) Rosacea
Doxycycline 40 mg modified-release (ORACEA®) reduces inflammatory lesions by 60–70% in moderate-to-severe rosacea.
3) Rheumatologic Disorders
Reactive arthritis: Decreases synovial inflammation.
Sarcoidosis: May reduce granuloma formation via immunomodulation.
Veterinary Applications
Common Infections in Animals
1) Avian Medicine
Ornithosis: Doxycycline powder (20% soluble) mixed into drinking water at 5 g/gallon for 7–10 days treats Chlamydia psittaci in parrots and pigeons.
Mycoplasmosis: Chronic respiratory infections in poultry are managed with 10–20 mg/kg body weight daily.
2) Companion Animals
Canine Lyme Disease: 5 mg/kg twice daily for 30 days post-tick bite.
Feline Upper Respiratory Infections: 2.5–5 mg/kg daily for 7–14 days for Chlamydia felis or Bordetella bronchiseptica.
3) Livestock
Leptospirosis in Cattle: 2.2 mg/kg daily for 7 days prevents abortion storms.
Swine Dysentery: 10 mg/kg daily in feed for 10–14 days controls Brachyspira hyodysenteriae.
Administration Methods
1) Oral Suspension: Doxycycline powder is mixed with water or milk replacers for easy dosing in birds and neonates.
2) Topical Applications: Ointments containing 3% doxycycline treat eye infections in horses and dogs.
3) Injectable Solutions: Reserved for severe cases (e.g., septicemia), though oral routes are preferred due to cost and safety.
Advantages of Doxycycline Powder
Flexibility in Dosage and Administration:
1) Customized dosing: Ideal for pediatric patients (e.g., 1–2 mg/kg/day) or those requiring precise titration.
2) Enteral feeding tubes: Can be mixed with water for administration for patients unable to swallow tablets.
3) Veterinary use: Easily measured for large animals (e.g., horses, cattle) where liquid formulations are impractical.
Cost-Effectiveness: Generic doxycycline powder is inexpensive, making it accessible in low- and middle-income countries.
Stability and Shelf Life: When stored properly (dry, cool, away from light), doxycycline powder retains potency for up to 5 years, unlike some liquid formulations that degrade faster.
Side Effects and Safety Profile
Common Adverse Reactions
1) Gastrointestinal: Nausea (10–15% of patients), vomiting, and diarrhea are common, often mitigated by taking the drug with food.
2) Photosensitivity: Up to 30% of users experience sunburn-like reactions, necessitating sunscreen and protective clothing.
3) Yeast Infections: Doxycycline disrupts vaginal flora, increasing candida overgrowth risk.
Severe Reactions
1) Intracranial Hypertension: Rare but serious, this condition causes severe headaches and visual disturbances. A 2004 study linked prolonged doxycycline use to pseudotumor cerebri, particularly in women of childbearing age.
2) Stevens-Johnson Syndrome: A life-threatening blistering rash reported in <0.1% of cases, often requiring hospitalization.
3) Tooth Staining: Permanent discoloration occurs in 3–6% of children exposed during tooth development, as documented in a 2006 case report.
Drug Interactions
Doxycycline interacts with:
1) Antacids/Supplements: Calcium, magnesium, and iron reduce absorption if taken concurrently. Patients are advised to space doses by 2 hours.
2) Warfarin: Doxycycline enhances anticoagulant effects, increasing bleeding risk.
3) Retinoids: Concurrent use with isotretinoin (for acne) raises intracranial hypertension risk.
Emerging Research and Future Directions
Oncology
1) MMP Inhibition: Doxycycline's anti-metastatic effects are being tested in breast cancer and glioblastoma trials.
2) Senolytic Therapy: Early studies suggest it may clear senescent cells, delaying aging-related diseases.
Neurodegenerative Diseases
Alzheimer's Disease: Doxycycline reduced amyloid-beta plaques by 60% in mouse models, prompting Phase II human trials.
Antiviral Applications
1) Dengue Virus: In vitro studies show doxycycline inhibits viral replication by blocking host cell proteases.
2) SARS-CoV-2: A 2020 study reported reduced viral load in COVID-19 patients, though larger trials are needed.
Doxycycline powder remains a vital tool in combating bacterial infections across species, balancing efficacy with a manageable safety profile. Its versatility-from treating avian respiratory diseases to preventing bioterrorism-related threats-underscores its importance in modern medicine. However, judicious use is essential to mitigate risks like resistance and adverse reactions. Patients and veterinarians alike must adhere to dosage guidelines, monitor for side effects, and avoid unnecessary long-term therapy. As research continues to uncover novel applications (e.g., MMP inhibition in chronic wounds), doxycycline's role in healthcare is poised to expand, provided it is wielded with precision and caution.
Frequently Asked Questions
What infections will doxycycline clear up?
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Doxycycline is mainly used to treat bacterial infections, including some:
urinary tract infections (UTIs)
sexually transmitted infections (STIs)
chest infections.
gum infections.
Which two diseases can doxycycline prevent?
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Doxycycline (or "doxy" for short) is a common antibiotic. Recent research shows that taking doxycycline within 3 days (or 72 hours) after sex can help some people reduce the chances of getting syphilis, chlamydia, and, in some studies, gonorrhea. This prevention strategy is called doxy PEP.
Is doxycycline a high risk drug?
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The Warnings and Precautions sections of package inserts for doxycycline alert users to a number of risks: permanent tooth discoloration and enamel hypoplasia during tooth development in a child if taken in the last half of the mother's pregnancy.
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