Tydox
Generic Name
doxycycline
Manufacturer
Popular Pharmaceuticals Ltd.
Country
Bangladesh
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Description
Overview of the medicine
Doxycycline is a broad-spectrum tetracycline antibiotic used to treat a wide range of bacterial infections, including respiratory tract, urinary tract, skin, and sexually transmitted infections. It is also used for malaria prophylaxis and severe acne.
Uses & Indications
Dosage
Adults
Standard adult dose is 100 mg orally every 12 hours for the first day, followed by 100 mg once daily, or 50 mg every 12 hours. For severe infections, 100 mg every 12 hours may be used throughout the treatment course.
Elderly
No specific dose adjustment is usually required based on age alone, but caution should be exercised in those with underlying hepatic impairment.
Renal_impairment
No significant dose adjustment needed for most patients with renal impairment, as doxycycline is primarily eliminated via non-renal pathways.
How to Take
Take the capsule with a full glass of water (approx. 240 ml), preferably while standing or sitting upright, to minimize the risk of esophageal irritation or ulceration. Do not lie down for at least 30-60 minutes after taking the medicine. It can be taken with or without food, but if stomach upset occurs, it may be taken with a meal (avoiding dairy).
Mechanism of Action
Doxycycline inhibits bacterial protein synthesis by binding reversibly to the 30S ribosomal subunit of susceptible bacteria, thereby preventing the attachment of aminoacyl tRNA to the acceptor site on the mRNA-ribosome complex.
Pharmacokinetics
Onset
Therapeutic effects usually start within 1-2 hours.
Excretion
Primarily excreted in feces via bile, with a smaller portion excreted renally. This makes it suitable for use in patients with renal impairment without major dose adjustments.
Half life
Plasma elimination half-life is 16-22 hours, allowing for once or twice daily dosing.
Absorption
Well absorbed orally (90-100%). Peak plasma concentrations are reached within 1-2 hours after administration. Absorption is decreased by food, particularly dairy products and calcium-containing antacids.
Metabolism
Partially metabolized in the liver to inactive metabolites.
Side Effects
Contraindications
- Hypersensitivity to doxycycline or other tetracyclines.
- Pregnancy (second and third trimesters) and lactation due to potential for permanent tooth discoloration and inhibition of bone growth in the fetus/infant.
- Children under 8 years of age (except for severe life-threatening conditions like anthrax), due to risk of permanent tooth discoloration and enamel hypoplasia.
Drug Interactions
Methotrexate
Tetracyclines may increase methotrexate plasma concentrations, leading to increased toxicity.
Oral contraceptives
May reduce the efficacy of hormonal contraceptives, leading to breakthrough bleeding or unintended pregnancy. Advise alternative contraception.
Warfarin and other anticoagulants
Doxycycline may potentiate the anticoagulant effect. Close monitoring of INR is recommended.
Barbiturates, carbamazepine, phenytoin
May decrease doxycycline's half-life by inducing hepatic enzymes, potentially reducing its efficacy.
Iron preparations and zinc supplements
Decrease absorption of doxycycline. Administer doxycycline 2 hours before or 4 hours after these agents.
Antacids containing aluminum, calcium, or magnesium
Reduce oral absorption of doxycycline. Administer doxycycline 2 hours before or 4 hours after these agents.
Storage
Store in a cool, dry place, below 30°C, protected from light and moisture. Keep out of reach of children.
Overdose
In case of overdose, general supportive measures should be instituted immediately. Gastric lavage may be indicated. Doxycycline is not readily removed by hemodialysis. Treatment is primarily symptomatic and supportive.
Pregnancy & Lactation
Pregnancy Category D: Doxycycline can cause permanent tooth discoloration (yellow-gray-brown) and inhibition of bone growth in the fetus during the second and third trimesters. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Lactation: Doxycycline is excreted in breast milk. Due to the potential for serious adverse reactions in nursing infants (e.g., tooth discoloration), a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Side Effects
Contraindications
- Hypersensitivity to doxycycline or other tetracyclines.
- Pregnancy (second and third trimesters) and lactation due to potential for permanent tooth discoloration and inhibition of bone growth in the fetus/infant.
- Children under 8 years of age (except for severe life-threatening conditions like anthrax), due to risk of permanent tooth discoloration and enamel hypoplasia.
Drug Interactions
Methotrexate
Tetracyclines may increase methotrexate plasma concentrations, leading to increased toxicity.
Oral contraceptives
May reduce the efficacy of hormonal contraceptives, leading to breakthrough bleeding or unintended pregnancy. Advise alternative contraception.
Warfarin and other anticoagulants
Doxycycline may potentiate the anticoagulant effect. Close monitoring of INR is recommended.
Barbiturates, carbamazepine, phenytoin
May decrease doxycycline's half-life by inducing hepatic enzymes, potentially reducing its efficacy.
Iron preparations and zinc supplements
Decrease absorption of doxycycline. Administer doxycycline 2 hours before or 4 hours after these agents.
Antacids containing aluminum, calcium, or magnesium
Reduce oral absorption of doxycycline. Administer doxycycline 2 hours before or 4 hours after these agents.
Storage
Store in a cool, dry place, below 30°C, protected from light and moisture. Keep out of reach of children.
Overdose
In case of overdose, general supportive measures should be instituted immediately. Gastric lavage may be indicated. Doxycycline is not readily removed by hemodialysis. Treatment is primarily symptomatic and supportive.
Pregnancy & Lactation
Pregnancy Category D: Doxycycline can cause permanent tooth discoloration (yellow-gray-brown) and inhibition of bone growth in the fetus during the second and third trimesters. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Lactation: Doxycycline is excreted in breast milk. Due to the potential for serious adverse reactions in nursing infants (e.g., tooth discoloration), a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
24 months from manufacturing date.
Availability
Pharmacies, Hospitals
Approval Status
Approved by major regulatory bodies
Patent Status
Generic available
WHO Essential Medicine
YesClinical Trials
Doxycycline has been extensively studied since its introduction. Ongoing clinical trials may explore new indications, optimized dosing regimens, or its efficacy against emerging resistant strains of bacteria. Research also focuses on its anti-inflammatory and immunomodulatory properties for conditions like rosacea.
Lab Monitoring
- Liver function tests (for prolonged therapy or in patients with pre-existing hepatic impairment)
- Complete blood count (for prolonged therapy)
- Renal function tests (not routinely required unless severe pre-existing impairment)
Doctor Notes
- Emphasize patient education on proper administration to avoid esophageal irritation and photosensitivity.
- Counsel female patients on potential reduction in oral contraceptive efficacy and need for alternative birth control.
- Monitor for signs of C. difficile infection or fungal overgrowth, especially with prolonged use.
- Avoid in children under 8 years and pregnant/lactating women unless absolutely necessary for life-threatening conditions.
Patient Guidelines
- Take with plenty of water and remain upright for at least 30-60 minutes after taking the capsule to prevent esophageal irritation.
- Avoid direct sunlight and use protective clothing/sunscreen due to photosensitivity.
- Do not take with dairy products, antacids, or iron supplements. Separate administration by at least 2 hours.
- Complete the full course of treatment as prescribed, even if symptoms improve, to prevent resistance.
Missed Dose Advice
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Driving Precautions
Doxycycline may cause dizziness, visual disturbances, or blurred vision in some patients. If you experience these effects, avoid driving or operating machinery.
Lifestyle Advice
- Stay well-hydrated throughout the treatment period.
- Avoid excessive sun exposure and use sun protection (hats, long sleeves, sunscreen) outdoors.
- Maintain good oral hygiene.
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