Doxycycline 100 mg Capsules

Brand name

The drug is known in medical practice under the trade name Doxycycline. This designation is assigned to the drug in pharmaceutical registries and is used by healthcare professionals and patients to identify it in pharmacies and medical institutions. The name reflects the belonging of the drug to a certain group of antibiotics and has become widely recognized due to its use in the therapy of various infectious diseases. The developers chose this name to distinguish it from other drugs with similar properties, emphasizing its effectiveness and versatility.

International Nonproprietary Name (INN)

The international nonproprietary name of this medicine is doxycycline. This term has been adopted by the international community to designate the active ingredient that provides the therapeutic action. Doxycycline belongs to the tetracycline class, known for its wide range of antibacterial activity. The name is standardized by the World Health Organization and is used universally, which allows a unified approach to the prescription and production of this drug regardless of region or brand.

Form of release

The drug is presented in several forms, which makes it convenient for use depending on the clinical situation and the age of the patient. The main options include:

• Capsules for oral administration with dosages of 50 mg, 100 mg and 200 mg of the active substance. This form is the most common for treatment at home.
• Tablets, including soluble coated tablets, with dosages of 100 mg and 200 mg, designed for convenient administration and rapid absorption.
• Lyophilizate for preparation of solution for intravenous administration (100 mg in a vial), used in hospitals for severe infections.
• Syrup or suspension (in some countries) with a concentration of 50 mg/5 ml, often used in pediatrics.

Each form is tailored for specific use: capsules and tablets are suitable for outpatient treatment, injections for emergency therapy in hospital settings, and syrup for children or patients with difficulty swallowing solid dosage forms.

Composition

The main active ingredient is doxycycline, an antibiotic from the group of tetracyclines, which has a pronounced antibacterial effect. Depending on the form of release, the auxiliary components may differ. In capsules, the following are used:

• Microcrystalline cellulose - a filler that provides uniform distribution of the active substance.
• Lactose monohydrate - an auxiliary substance to create mass.
• Magnesium stearate - a lubricating agent that facilitates the manufacturing process.
• Gelatin - capsule shell material.
• Colorant (e.g., titanium dioxide) - for coloring the shell.

Tablets may add croscarmellose sodium as a disintegrant and a film coating of hypromellose. The solution for injection contains mannitol as a stabilizer, as well as water for injection and pH adjusters such as sodium hydroxide. The syrup includes sucrose to improve taste, flavorings (such as raspberry), and preservatives to extend shelf life.

Pharmacologic Properties

Pharmacodynamics

The drug has bacteriostatic action by inhibiting protein synthesis in bacterial cells. It binds to the 30S-subunit of ribosomes, disrupting the translation process and the formation of peptide chains, which stops the growth and reproduction of microorganisms. The activity extends to a wide range of pathogens, including Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae, Bacillus anthracis) and Gram-negative microorganisms (Escherichia coli, Haemophilus influenzae, Neisseria gonorrhoeae). Of particular value is its action against intracellular pathogens such as Chlamydia trachomatis, Mycoplasma pneumoniae and Rickettsia spp.

The mechanism of action allows it to effectively fight infections resistant to other classes of antibiotics, such as penicillins or cephalosporins. The drug also has anti-inflammatory properties, reducing the production of pro-inflammatory cytokines, making it useful in some non-infectious conditions such as acne or rosacea. The effect occurs within hours of initiating therapy, providing control of the infectious process.

Pharmacokinetics

Absorption

After oral administration, the active substance is absorbed in the gastrointestinal tract, predominantly in the upper small intestine. Maximum concentration in plasma is reached in 2-3 hours. Bioavailability is 90-100%, which is higher than that of other tetracyclines due to lower sensitivity to the formation of chelates with metal ions. Taking food, especially rich in calcium or magnesium, reduces absorption by 20-30%, so it is recommended to take the drug on an empty stomach.

Distribution

The component is well distributed in the body, penetrating into the lungs, liver, kidneys, bones, skin and soft tissues. Binding to plasma proteins reaches 80-93%, which provides a stable presence in the blood. The drug is able to accumulate in tissues, including dental enamel and bone tissue, which is important to take into account during prolonged use. Penetration through the blood-brain barrier is limited, but increases with inflammatory processes in the cerebral membranes.

Metabolism

Metabolism is minimal: about 60-70% of the dose taken remains unchanged. A small portion is metabolized in the liver to form inactive derivatives, which reduces the burden on this organ compared to other antibiotics.

Excretion

It is excreted through the kidneys (30-40% unchanged) and with bile (40-60%), partially through the intestine. The elimination half-life is 16-22 hours, which allows taking the drug 1-2 times a day. Prolonged excretion provides a stable concentration in tissues, which is especially useful in chronic infections.

Indications for Use

The drug is used for the treatment of infections caused by sensitive microorganisms:

• Infections of the respiratory tract: bronchitis, pneumonia, sinusitis.
• Infections of the genitourinary system: urethritis, cystitis, pyelonephritis, prostatitis.
• Infections of the skin and soft tissues: acne, furunculosis, infected wounds.
• Sexually transmitted infections: chlamydia, gonorrhea, syphilis (if allergic to penicillin).
• Rickettsioses: Q fever, Rocky Mountain spotted fever
• Malaria (prophylaxis and treatment in combination with other agents).
• Infections caused by Bacillus anthracis (anthrax), including post-exposure prophylaxis.

The drug is also used for chronic inflammatory conditions such as rosacea and as prophylaxis after tick bites in endemic areas.

Contraindications

Application is prohibited in:

• Hypersensitivity to tetracyclines or components of the formulation.
• Pregnancy and lactation due to the risk of exposure to the fetus and newborn.
• Children under 8 years of age (risk of staining of teeth and retardation of bone growth).
• Severe hepatic impairment without dose adjustment.
• Porphyria due to risk of exacerbation.

With caution prescribe in gastric diseases (ulcer, gastritis) and photosensitivity.

Method of Administration and Dosage

How to take

Capsules or tablets are taken orally, drinking plenty of water (200-250 ml), preferably on an empty stomach 1-2 hours before a meal or 2 hours after to avoid interaction with food. It is recommended to take sitting or standing to prevent esophageal irritation. Solution for injection is administered by intravenous drip (within 1-2 hours) after dilution in physiologic solution.

Dosages for adults and children

Dosage depends on the nature of the infection:

• Adults: the first day - 200 mg (once or 100 mg twice), then 100 mg once a day, course 7-14 days.
• Children over 8 years of age (body weight >45 kg): 4 mg/kg on the first day, then 2-4 mg/kg/day.
• Injections: 200 mg/day in 1-2 administrations, with conversion to oral administration.
• Malaria prophylaxis: 100 mg/day 1-2 days before travel and 4 weeks after.

Dose correction for certain conditions

In renal insufficiency, no correction is necessary due to excretion through the bile. In hepatic insufficiency:

• Moderate: dose reduction by 50%.
• Severe: the interval is increased to 24-48 hours.

Side Effects

Unwanted reactions include:

• Gastrointestinal: nausea, vomiting, diarrhea, esophagitis.
• Skin: photosensitivity, rash, pruritus.
• Hematologic: anemia, thrombocytopenia.
• Nervous: dizziness, headache.
• hepatic: increase in transaminases.

Treatment should be discontinued if symptoms are severe.

Overdose

Symptoms of overdose

Exceeding the dose causes nausea, vomiting, dizziness, convulsions, increased intracranial pressure.

First aid measures

In overdose:

• Stop taking it.
• Rinse stomach (within 1-2 hours).
• Provide hydration and symptomatic therapy.
• Seek medical attention.

Drug Interactions

Influence on the effects of other drugs

The medication affects:

• Antacids (with calcium, magnesium): decrease in absorption.
• Barfarin: increased anticoagulant effect.
• Penicillins: decrease in their effectiveness.

Compatibility with alcohol and food

Alcohol reduces efficacy and increases toxicity, it is avoided. Dairy products slow absorption.

Special Precautions

Use in pregnancy and breastfeeding

It is contraindicated in pregnancy (category D) and lactation due to the risk to the fetus and child.

Effects on driving and operating machinery

Dizziness may make it difficult to drive or operate machinery.

Particulars of Use in the Elderly and Children

In the elderly, monitoring of liver function is required. Do not use in children under 8 years of age due to risk to teeth and bones.