Doxycycline is a semi-synthetic broad-spectrum antibiotic tetracycline. The mechanism of action is associated with a violation of the production of proteins in bacterial cells. It acts bacteriostatically (stops the growth and reproduction of microbes). Doxycycline penetrates the bacterial cell, interacts with the aminoacyl center of the ribosomal 50S subunit. It disrupts the peptidyl translocase reaction, preventing tRNA from delivering new amino acids to the ribosome to build the protein chain. In this case, human ribosome Ha has no effect, which is associated with the presence of its 70S ribosome subunit (instead of the 50S subunit).
Gram-positive (Gr +) aerobic bacteria: Streptococcus viridans, Streptococcus haemolytіcus, Streptococcus pneumonіae, Staphylococcus spp. (including Staphylococcus aureus, Staphylococcus epidermidis), Enterococcus faecalis, Listeria spp. (including Listeria monocytogenes), Bacillus anthracis;
Gram-negative aerobic bacteria: Brucella spp., Escherichia coli, Neisseria meningitides, Neisseria gonorrhoeae, Haemophilus influenzae, Shigella spp., Yersinia spp., Salmonella spp., Pasteurella spp., Vibrio spp., Legella frangis, Klebs. , Treponema spp. (including strains resistant to beta-lactam antibiotics), Rickettsiae spp., Campylobacter spp .;
Gram-negative (Gr-) anaerobic microorganisms: Enterobacter spp., Clostridium spp., Bacteroіdes spp.
Highly active against Chlamydia spp., Mycoplasma spp .;
some protozoa: Entamoeba histolytica, P. falciparum.
Most strains of Serratia spp., Proteus spp., Pseudomonas spp., Fungi are resistant to doxycycline (with the exception of Actynomyces spp.).
Bacteria that are resistant to tetracycline are cross-resistant to doxycycline.
Doxycycline is able to inhibit connective tissue matrix metalloproteinases (enzymes that destroy collagen, proteoglycans), and reduce the severity of cartilage damage in deforming osteoarthritis.
This medicine is prescribed when:
with infection of the upper / lower respiratory tract, as well as ENT organs (pneumonia, otitis media, sinusitis, exacerbation of chronic bronchitis in persons under 65 years of age);
with urogenital infection (pyelonephritis, urethritis, prostatitis, orchiepididymitis, cervicitis, endometritis);
with mycoplasmal, chlamydial infection, including Reiter’s syndrome;
with gonorrhea, primary / secondary syphilis, and patients with allergies to beta-lactam antibiotics;
with infection of the biliary tract (cholangitis, cholecystitis);
with intestinal infection (travelers diarrhea, gastroenterocolitis, yersiniosis, shigellosis);
with infection of the skin, soft tissues (acne, abscess, phlegmon, furunculosis);
with infected burns, wounds;
with legionellosis (“legionnaire’s disease”);
with rickettsiosis or other infections caused by rickettsia sensitive to this antibiotic;
with especially dangerous infections: cholera, plague, tularemia, glanders, anthrax, brucellosis;
with Lyme disease (tick-borne borreliosis);
with malaria (for treatment, prevention);
with amoebic dysentery;
with granulocytic ehrlichiosis;
for the prevention of infection in medical abortion.
Do not prescribe doxycycline:
with an allergy to doxycycline, other tetracyclines;
with intolerance to excipients;
at the age of 12 years;
with body weight less than 45 kg;
during pregnancy / lactation;
with leukopenia (a decrease in the number of white blood cells in the blood);
with severe functional impairment of the liver / kidneys.
Pregnancy and lactation
In experiments conducted on animals, it was shown that this antibiotic causes a delay in the development of the skeleton of the fetus, so its use during pregnancy is contraindicated.
Doxycycline is able to be excreted in a woman’s milk, so breast-feeding is stopped during treatment.
Dosage and administration
Capsules are taken orally, with a glass of water, during or after a meal.
Adults, children over 12 years of age with a body weight of more than 45 kg are prescribed 200 mg on the first day in one or two doses, on the second day – 100 mg x1 times / day. The maximum dose that can be taken per day for severe infections is 200 mg in 1–2 doses.
The duration of treatment depends on the type of infection and is usually 5–10 days.
In Lyme disease, the course of treatment is 3-4 weeks, with brucellosis – 1.5-6 months.
In case of gonorrhea, women are prescribed 200 mg / day in 1 dose, for men – 200-300 mg / day (2-3 capsules) in 1 dose for 5 days.
With syphilis, a dose of 300 mg / day for 10 days is recommended.
When treating chlamydial, mycoplasma infection, 200 mg / day is prescribed for 7 days.
In the treatment of acne, 50 mg / day is used for 6-12 weeks.
For the prophylaxis of infections in medical abortion, they are prescribed twice as 100 mg 1 hour before the procedure and 200 mg 30 minutes after it.
In patients with kidney failure, a reduction in the daily dose is required.
Overdose symptoms: with the introduction of high doses, especially for patients with impaired liver function, neurotoxic reactions may develop, manifested by convulsions, dizziness, vomiting, impaired consciousness (due to increased intracranial pressure).
Overdose treatment: drug withdrawal, gastric lavage, intake of sorbents (activated carbon), antacids, magnesium sulfate – to prevent further absorption of the drug, symptomatic and supportive therapy. There is no specific antidote. Hemodialysis, peritoneal dialysis are ineffective.