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Doxycycline is an antibiotic drug which is used to treat a variety of bacterial infections including prostate infection. This medication can be used in all those medical conditions where the penicillin cannot be used. The active ingredients of this drug are Doxycycline Calcium, Doxycycline Hyclate and Doxycycline Monohydrate. 


Indications: Although this list is not complete, Doxycycline (Doryx) is indicated in the following medical conditions:  

  • Prostate infections (prostatitis)
  • Bacterial infections which include Rocky Mountain spotted fever 
  • Some sexually transmitted infections 
  • Respiratory tract infections 
  • Eye infections and other fevers caused by ticks, fleas and lice. 
  • Amebiasis, intestinal infection caused by the parasite Entamoeba histolytica  
  • Infections caused by Clostridium species. 
  • Listeriosis, any type of infection caused bacteria called Listeria monocytogenes. 

Dosage: The dosage of this drug is prescribed by a health care provider depending on the medical history and conditions of the patient. The dosage should not be changed without the approval of the doctor. The usual Doxycycline dosage is 200 mgs on the first day of the treatment and should be taken as 100 mg for every 12 hours.  After this a dose of 100 mg may be taken as a maintenance dose in a single time or 50 mg for every 12 hours. Usually, the 100 mg dosage is prescribed for severe infections like chronic urinary tract infection.  


For children below the age of 8 years old, the prescription may vary according to the body weight of the children. For children above the age of 8, adult dosage may be given. 


Contraindications: The drug may be contraindicated if, 

  • The patient is suffering from a liver disease, 
  • The patient is suffering from an asthma or sulfite allergy 
  • The patient is having any history of kidney disease 
  • The patient is allergic to Doxycycline or to other tetracycline antibiotics namely, demeclocycline (Declomycin), minocycline (Dynacin, Minocin) or tetracycline (Brodspec, Panmycin, Sumycin, Tetracap). 

Mechanism of Action (MOA): Doxycycline penetrates into the bacterial cells and stops them from further production. Hence, bacteria cannot reproduce and dies by the defence mechanisms of the drug. The bacteriostatic property of this drug works against gram-positive as well as gram-negative bacteria. In gram-negative bacteria, doxycycline gets transported into the cell occurs either through passive diffusion or by an energy-driven transport system. Since doxycycline is more lipophilic in comparison to other tetracycline drugs, it passes easily through the lipid bi-layer of bacteria. 


Doxycycline also possesses several non-antibiotic properties such as:  

  • Anti-inflammatory effect 
  • Inhibition of gelatin and collagen production 
  • Reduction in formation of newer blood vessels 
  • Reduction in apoptosis 

Interactions: If the Doxycycline (Doryx) is taken in combination of certain drugs, the effects may be increased or decreased or may even be altered.  Consultation with the doctor is essentially important in all such cases.  Blood-thinning medications such as Warfarin, penicillin, phenytoin; antacids containing aluminium, calcium or magnesium, birth control pills etc are some of the interactions which are taken with this drug. 


Side Effects: Some of the possible side effects of this drug include:  

  • Gastrointestinal disorders such as nausea, diarrhoea, vomiting, dysphagia, and enterocolitis 
  • Skin disorders: rashes, Stevens-Johnson syndrome, epidermal necrolysis and Exfoliative dermatitis 
  • Kidney problems (Renal toxicity), hypersensitivity reactions, hemolytic anemia, neutropenia and thrombocytopenia