What Is Doxycycline?

Doxycycline is the primary broad-spectrum antibiotic of tetracycline antibiotics class, it is an antibiotic for many types of bacteria and some parasitic infections. It was first discovered in 1957, became available in 1967 under the brand name of Doryx and Doxy. With time and continuous chemical modification, we reached to this current form of the drug. It is one of the essential, necessary medicines in any health care system. It is now produced in most developing, and developed countries due to its high community need as it the most prescribed antibiotic in the united states last year and low cost of production.

Mechanism of Action

Doxycycline is a broad-spectrum bacteriostatic antibiotic. It works on stopping reproduction by inhibiting protein synthesis, not by direct killing. It binds to a small 30s ribosomal subunit of 2 subunits of the ribosome, causing the prevention of completion of bacterial protein synthesis, as it doesn’t permit binding of t-RNA to mRNA at the ribosomal subunit causing no amino acids could be added to polypeptide chains, and no proteins are formed. If you stop growth, you destruct cells allowing the immune system to kill and get rid of the bacteria.

Pharmacology of the Drug

Absorption : high lipophilic highly absorbed into cells.
Excretion: Renal excretion
Metabolism : liver metabolism

Medical Use
It is used to treat so many diseases besides being Antibacterial, as it is used as an antimalarial, anthelminthic and also as an adjuvant drug for other conditions.

1- Antibacterial

  • It is used to treat many bacterial infections, especially urinary tract infections caused by klebsiella and respiratory infection caused by streptococcus pneumonia and Haemophilus influenza. It deals mainly with gram-negative bacteria as gram-positive show rising resistance like Moraxella, Brucella, Haemophilus influenza, Pseudomonas aeruginosa, and mycoplasma pneumonia.
  • It is the first line of treatment of brucellosis in combination with streptomycin. It is used for the treatment of diseases caused by rickettsia as Rocky Mountain spotted fever, typhus fever, Q fever. In addition to, Relapsing Fever due to Borellia recurrentis. It is a significant drug in cholera protocol and Lyme disease. It also found in the international protocol of plaque. Dermatologists prescribe it for acne.
  • It is used as an alternative to penicillin due to its resistance in syphilis, Vincent angina, actinomycosis, listeriosis.

2- Anti malarial
New guidelines say that a combination of Doxycycline and quinine is used to treat uncomplicated malaria.

3- Antihelminthic
It proved efficiency against microfilaria and elephantiasis.

Adverse Effects

1- GIT disturbance and less Clostridium Difficile Colitis.
2- Skin erythema due to sun exposure during treatment of malaria.
3- yellow eyes, teeth, and skin
4- uncomfortable urination
5- headache
6- back pain
7- jaundice
8- hypersensitivity


1- Antacids, Ca, Fe supplements decrease absorption of Doxycycline
2- Some researchers say that there is a relation between Doxycycline and contraceptive pills.
3- Doxycycline could increase blood thinning with warfarin.
4- A combination of Doxycycline and isotretinoin could increase intra-cerebral pressure result in a condition called Pseudotumor Cerebri.


In conclusion, Doxycycline is a vital antibacterial agent, you have to take it by a medical prescription in case of infection of the respiratory or urinary system.

Author: Guest Author

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