Doxycycline – drug characteristics, indications, contraindications and dosage

Proven content

Doxycycline is an antibiotic that is an essential ingredient in antibacterial drugs. This compound is used primarily in the treatment of infections caused by sensitive microorganisms, including respiratory tract infections, urogenital infections, gastrointestinal infections, and skin and soft tissue infections. What are the contraindications to the use of drugs with doxycycline, how to dose this antibiotic and can its use cause side effects?

What is doxycycline?

Doxycycline is an organic chemical compound. It is a semi-synthetic antibiotic that belongs to the group of tetracyclines, i.e. broad-spectrum antibiotics. Strains of anaerobic bacteria, protozoa and chlamydia are sensitive to the action of doxycycline.

Drugs whose basic ingredient is doxycycline are relatively inexpensive, so they are often used to treat infections in both humans and animals.

Tetracyclines were discovered in the 40s. It has been shown that doxycycline is much better absorbed from the gastrointestinal tract than other tetracycline drugs. This, in turn, makes patients more likely to take this antibiotic because it harms the kidneys less.

The main feature of doxycycline is that it is bacteriostatic, that is, it inhibits the synthesis of whitek, thus preventing the growth and multiplication of bacterial cells.

If you want to know more about tetracyclines read on: Tetracycline TZF (tetracycline)

How does doxycycline work?

As mentioned before, the feature of doxycycline is its bacteriostaticity. The mechanism of action of antibiotics with doxycycline is the inhibition of ribosomal protein biosynthesis in bacterial cells. This happens by binding to the S30 ribosomal subunit and then blocking it. The ribosome is the element of the cell that is used to make proteins and is made up of two units: small S30 and large S50.

Precisely because the mechanism of action of doxycycline, it inhibits cell growth rather than killing it, that it is called bacteriostatic antibiotics. Tetracycline antibiotics have a wide range of action, which means that they are active against many bacteria.

It is also worth noting that antibiotics of the tetracycline group combine with divalent and trivalent metal ions. The combinations are very difficult to dissolve in water, so they are practically not absorbed from the gastrointestinal tract and therefore have no therapeutic properties.

Therefore, it must be remembered that drugs with doxycycline should not be administered simultaneously with drugs or other pharmaceutical agents that contain metal ions. You should also not eat foods rich in calcium, iron, aluminum or magnesium salts.

Another important piece of information is that, as with many other antibiotics, also here, the long-term use of doxycycline selects a high percentage of resistant strains. This strain resistance is due to a reduction in the ability of the drug to penetrate the bacterial cell or the ability of the bacteria to actively remove the drug to the outside.

Doxycycline easily penetrates into tissues and body fluids, and therefore reaches high concentrations, primarily in the prostate, ovaries, uterus, bladder, liver, muscles, bronchi, lungs and lymph nodes. In addition, it also penetrates the placenta and into breast milk. With normal renal function, 40% of the drug is excreted in the urine unchanged, while the remainder as metabolites in the faeces.

If you want to find out how you should take your medications to be effective, check out: How to take medications effectively?

Doxycycline – indications for use

Doxycycline is an antibiotic that is used to treat infections with bacteria. Indications for the use of doxycycline there are the following diseases and conditions:

1. upper and lower respiratory tract infectionsincluding: tonsillitis, pharyngitis, middle ear, sinus, bronchitis and lung inflammation;
2. urinary tract infectionsincluding: cystitis and urethritis;
3. sexually transmitted diseases especially those caused by Chlamydia trachomatis, such as: soft ulcer, inguinal granuloma, syphilis or gonorrhea;
4. soft tissue infections;
5. skin infections, including difficult to treat rosacea or common acne;
6. digestive tract infectionssuch as e.g. diarrhea;
7. ophthalmic infections – caused by strains of staphylococci and gonorrhea,
8. Lyme disease;
9. malaria;
10. typhus;
11. plague.

What are the most common bacterial diseases? Check: The most common bacterial diseases – overview and characteristics

Doxycycline – contraindications

Unfortunately, not every patient can take drugs with doxycycline in case of infection. First of all, doxycycline cannot be used in case of allergy or hypersensitivity to this compound. In addition, this drug should not be taken by patients with severe liver failure.

Please note that doxycycline can be given to children over 12 years of age. The drug should not be used during the period of tooth growth due to the possibility of permanent discoloration.

Discoloration on the teeth results from the deposition of a tetracycline-calcium-phosphate complex, which gives the teeth a gray-brown or brown-black color. Contraindication to the use of doxycycline there is also pregnancy and breastfeeding.

What should you know about drug allergies? Check: Drugs are also allergenic

Doxycycline – special precautions

In some cases, special care should be taken when using doxycycline. Some diseases or medications taken may constitute a contraindication to the use of doxycycline or require a change in the dosage of the antibiotic.

Therefore, before and during the use of drugs with doxycycline, special care should be taken in cases of:

1. liver dysfunction and the use of hepatotoxic drugs. When using such drugs, liver function tests and blood counts should be regularly performed;
2. blood coagulation disorders – the patient’s health should be monitored by blood tests, kidney and liver function tests;
3. myasthenia gravis, systemic lupus erythematosus or porphyria, as the use of doxycycline may worsen the symptoms of the disease;
4. galactose intolerance, lactase deficiency or malabsorption of glucose-galactose, preparations with doxycycline should not be used, because the tablets contain compounds to which the patient is allergic;

Additionally, when using drugs with doxycycline, remember to:

1. limit its use during the growth of teeth or bones;
2. avoid staying in sunny places, not exposing yourself to sunlight or UV rays (e.g. in a solarium), due to the risk of skin reactions to photosensitivity, such as: erythema, swelling, blisters or peeling of the skin;
3. take the antibiotic in a sitting or standing position and always drink it with plenty of water, as your esophagus may become inflamed or ulcerated when taking this medicine, especially if you take doxycycline just before going to bed or with too little fluid.

How to take care of your health when you decide to self-medicate? Read on: Responsible and safe self-treatment – what is worth remembering?

How to dose doxycycline?

The dosage of doxycycline is always determined by the doctor who prescribes this drug to the patient. The doctor also decides how long the therapy with the doxycycline antibiotic will last.

Standard treatment with doxycycline goes according to the scheme. On the first day, the patient takes an oral dose of between 200 and 300 mg of the drug. Then she takes a dose of 12 mg every 24 or 100 hours. The half-life of the antibiotic is approximately 16 hours. Doxycycline is excreted from the body in the bile, urine and faeces.

In case of specific ailments, the dosage of doxycycline may be as follows:

1. uncomplicated gonorrhea: 2 mg twice a day every 12 hours. Treatment lasts at least 100 days;
2. sexually transmitted diseases: 2 mg twice a day every 12 hours. Treatment lasts from 100 to 7 days;
3. primary and secondary syphilis: 200-300 mg daily in divided doses. Treatment may take up to 14 days;
4. Lyme disease: 2 mg twice a day every 12 hours. The treatment time for Lyme disease depends on the stage of the disease, usually from 100 to 14 days, but in the case of early diagnosis, treatment may take from 28 to 14 days;
5. in the prevention of malaria: 100 mg daily. Treatment begins 1-2 days before traveling to an area at risk for malaria. Doxycycline should be used throughout the stay in the endangered area and continued prophylactically for 4 weeks after returning.

Doxycycline is available in tablet form and as an intravenous formulation. The capsules should be taken orally, swallowed whole with a glass of water.

Intravenous doxycycline has not worked. The preparation is administered intravenously only as an intravenous infusion. The infusion duration is 1-4 hours.

If you want to know more about the properties of antibiotics, read on: Antibiotics – types, action, use and side effects [EXPLAIN]

Doxycycline and pregnancy and breastfeeding

The use of drugs with doxycycline during pregnancy and breastfeeding is possible only if its use in the mother is absolutely necessary. It can be used in pregnant women if it is not possible to use another drug.

However, it should be remembered that doxycycline passes through the placenta and also into breast milk. This typically results in the deposition of tetracyclines in the tooth compounds of infants.

In children, tooth discoloration, enamel damage, and bone growth retardation may occur. In addition, the use of drugs with doxycycline during pregnancy significantly increases the risk of liver damage.

Can I take medication while pregnant? Read: Pregnancy and medications

Doxycycline and other drugs

In any case, you should inform your doctor about the medications you have already taken, because the absorption of doxycycline from the gastrointestinal tract may be inhibited by other medications or preparations that include polyvalent aluminum, calcium and magnesium ions. These compounds are found in antacid products and preparations.

Doxycycline should not be used simultaneously with:

1. antibiotics with a bactericidal effect;
2. other tetracyclines as this causes kidney damage;
3. drugs that interfere with liver function;
4. sulfonylureas (oral antidiabetic drugs) and coumarin anticoagulants;
5. drugs inducing liver enzymes, i.e. barbiturates, acetaminophen or carbamazepine;
6. oral contraceptives as this may make them less effective.

What drugs should not be combined with each other? Check: Dangerous interactions

Doxycycline – side effects

The use of drugs with doxycycline can cause various side effects. Side effects may be very common, common, uncommon, rare or very rare. The side effects include:

1. influence on the results of diagnostic tests – taking drugs with doxycycline may interfere with the results of measurements of glucose, protein, urobilinogen and urinary catecholamines.
2. blood and lymphatic system disorders – anemia, neutropenia or eosinophilia may rarely occur. Porphyria has been very rarely diagnosed;
3. nervous system disorders – convex fontanel gland was rare in infants, which was caused by an increase in intracranial pressure. On the other hand, nausea, tinnitus, dizziness, blurred vision or labyrinth disorders have occurred very rarely;
4. ear and labyrinth disorders – uncommonly, patients reported atrial tinnitus and dizziness;
5. stomach and intestinal disorders – abdominal pain, vomiting, nausea, diarrhea or indigestion have occurred uncommonly. Difficulty swallowing or itching of the anus has rarely occurred. However, very rarely, patients had to deal with inflammation of the small intestine and colon;
6. disorders of the liver and bile ducts – liver dysfunction or hepatitis have rarely occurred. Very rarely jaundice;
7. disorder of the kidneys and urinary tract – there has been an increase in blood urea concentration rarely, and very rarely hypokalaemia or renal acidosis;
8. disorders of the skin and subcutaneous tissue – rashes or photodermatitis may not often occur. Rare dermatitis or urticaria. However, epidermal necrolysis is very rare;
9. musculoskeletal and connective tissue disorders – tooth and bone development disorders, irreversible tooth discoloration or bone fragility often occur;
10. infections and infestations – superinfections are rare, e.g. yeast infections, staphylococcal enteritis or vaginitis and stomatitis.

What diseases can you get infected by shaking hands? Read: Diseases that you can catch through a handshake

Effects of doxycycline overdose

Always take doxycycline exactly as prescribed by your doctor. Liver damage may occur in case of overdose with doxycycline. Liver damage is manifested by vomiting, fever attacks, jaundice, hematomas, tarry stools or increased levels of transaminases.

In the event of overdose, the patient is given drinking water and induced vomiting. If the patient has taken high doses of doxycycline, gastric lavage should be performed, and then activated charcoal and an active laxative should be administered. Experts say that hemodialysis and peritoneal dialysis are unlikely to be effective in this case.

The most popular drug that contains doxycycline in the composition is Doxycyclinum. Read more about this preparation: Doxycyclinum TZF

Before use, read the leaflet, which contains indications, contraindications, data on side effects and dosage as well as information on the use of the medicinal product, or consult your doctor or pharmacist, as each drug used improperly is a threat to your life or health. Do you need a medical consultation or an e-prescription? Go to halodoctor.pl, where you will get online help – quickly, safely and without leaving your home.