Doxycycline – Bacteria Immobilisation and Effective Osteoarthritis Treatment

Background

Doxycycline is a powerful antibiotic belonging to a group of antibiotics known as tetracyclines. It has been tried and tested for over 40 years having been first produced and clinically developed in the early 1960s.

As a broad-spectrum antibiotic, Doxycycline can be used to treat a wide variety of bacterial infections – both gram positive and gram negative. Its anti-inflammatory properties mean that Doxycycline may also help to slow the progression of osteoarthritis.

How does Doxycycline Work?

Doxycycline does not kill bacteria per se. Instead, it works by immobilising bacteria and then prevents them from replicating further by inhibiting (stopping) their protein production. This slows the growth of bacteria in the body.

Doxycycline has what is known as a long half-life. This means that a less frequent dosage regime can be adopted (often just once daily) when treating susceptible infections. Because of its long half-life and because it is absorbed fairly reliably, Doxycycline is sometimes preferred to other members of the tetracycline group. It also has the advantage that, unlike some other tetracyclines, it can be given (with care) to patients with renal impairment.

Which Infections Respond to Treatment with Doxycycline?

Doxycycline is used to treat many different bacterial infections as it is active against a number of different bacteria including those responsible for causing:

As can be seen from the above list (which is not intended to be exhaustive), Doxycycline is active against a number of diseases that are passed from animals to humans often by ticks, fleas and lice.

Additional Uses for Doxycycline.

If bacteriologic testing shows an appropriate susceptibility, Doxycycline may also be used to treat other diseases such as chronic bronchitis, acute bacterial sinusitis, chronic bacterial prostatitis, streptococcal throat infections, e.coli infections, Lyme disease, infections caused by shigella bacteria and methicillin-resistant staphylococcus aureus (MRSA). However, in these cases, Doxycycline should not be prescribed unless susceptibility has been shown to exist.

Doxycycline is also used in conjunction with other medications for the treatment of severe acne and amoebic dynsentery.

Doxycycline is approved treatment for inhalational anthrax but can also be used as a prophylaxis against the disease.

Doxycycline is also used as a prophylaxis against malaria. However, it should not be used as on its own as an initial treatment for malaria even if the parasite causing the infection has been shown to be susceptible to Doxycycline because the antimalarial effect of Doxycycline is delayed.

As Doxycycline is an antibiotic, it does not work against viral infections such as the common cold.

Doxycycline and Osteoarthritis

The use of Doxycycline is no longer restricted to simply fighting infection.

According to research results reported in July 2005, treatment with Doxycycline may be effective in slowing the progression of osteoarthritis. Osteoarthritis is the most common form of arthritis and is often referred to as “wear and tear” arthritis. It is typically seen as a primary disease in older people but can occur as a secondary condition in younger people.

Researchers undertook a 30 month clinical trial in which they compared the effectiveness of a dose of 100mg of Doxycycline twice daily as opposed to a placebo in around 400 women with knee osteoarthritis. At the end of the 30 month trial period, the results showed that the women who had taken Doxycycline had 33% less joint space narrowing. This is indicative of less cartilage loss. The treatment group were also less likely to report worsening of their knee pain than those who took a placebo.

With promising results like these, further trials need to be undertaken to fully understand the implications of Doxycycline and its effects on osteoarthritis

Dosage

For most infections, the usual dose is 200 mg of Doxycycline on the first day (as a single dose or 100 mg repeated after 12 hours), followed by 100 mg daily. However, relatively high doses may need to be given for urinary-tract infections because of its low renal excretion. Also, in severe infections the initial dosage is maintained throughout the course of treatment.

In patients with sensitive gonococcal infections Doxycycline may be given in a single dose of 300 mg, alone or followed by a second similar dose one hour later.

Due to the fact that oesophageal ulceration can be a problem if Doxycycline is not taken with enough fluid or when someone is lying down, Doxycycline should be taken with a full glass of water, in an upright position and at least one hour before going to bed.

In any event, you should remain upright for at least 30 minutes after taking Doxycycline.

These measures will help to prevent irritation of the oesophagus and stomach.

Side Effects

Gastrointestinal problems such as diarrhoea, mild nausea, vomiting and stomach upsets are some of the most common side effects linked to antibiotic medicines. However, gastrointestinal problems are reported less frequently with tetracycline antibiotics such as Doxycycline than with many other forms of antibiotics.

Other mild side effects may include white patches or sores inside the mouth or on the lips, sores or swelling in the genital or rectal area and vaginal itching or discharge.

Doxycycline can make skin more sensitive to sunlight and sunburn may result. Therefore avoid exposure to sunlight or artificial UV rays (sunlamps or tanning beds).

If exposed to sunlight, make sure adequate protective clothing and sunscreen of at least SPF15 is worn.

There is a slim risk of liver damage associated with prolonged use of Doxycycline.

Emergency help should be sought if you experience any allergic reaction such as difficulty in breathing. You should also seek immediate medical help if you have any serious side effects such as severe headache, dizziness, blurred vision, fever, chills, body aches and flu symptoms (this not a complete list of all the possible side effects).

Warnings

Although Doxycycline is likely to be less affected by milk or foods with calcium content than many other tetracyclines, its absorption is still affected by antacids and iron preparations. Therefore, do not take iron supplements, multivitamins, calcium supplements, antacids, or laxatives within 2 hours before or after taking Doxycycline.

Do not use Doxycycline if you are pregnant. It could cause harm to your unborn baby, including permanent discoloration of the teeth later in life. Do not use Doxycycline if you are breast feeding because Doxycycline passes into breast milk. It may affect bone and tooth development in a nursing baby.

Doxycycline is not approved for use in children under the age of 8 years. This is because it can cause permanent yellowing or greying of the teeth and can affect a child's growth. However, exceptions are made if a child is suffering from a potentially fatal illness. In this situation if the benefits of using Doxycycline outweigh the risks and there are few or no other alternatives available, such as with Rocky Mountain spotted fever and anthrax, Doxycycline can be used.

Doxycycline, along with many other antibiotics, was thought to interfere with the effectiveness of oral contraceptives. Although recent research has indicated that there is no significant loss in their effectiveness, many health care professionals still recommend the use of additional barrier contraceptives.

You should not use Doxycycline if you are allergic to it or similar medicines such as demeclocycline, tetracycline or minocycline.

Although Doxycycline can be used in patients with impaired renal function, you should consult your Doctor first as particular care including dose adjustment and possibly testing will need to be undertaken. You should also consult your Doctor before taking Doxycycline if you are suffering from liver disease.

Any unused Doxycycline should be thrown away when it expires. Expired Doxycycline can lead to a dangerous syndrome that causes kidney damage. It must not be taken after the expiration date on the packaging.

As is common with many medications, a number of other drugs may interfere with Doxycycline. These include cholesterol lowering medications such as cholestyramine, warfarin and antacids.

Before taking Doxycycline inform your health care professional of any medications that you are already taking, both prescription and over the counter, including vitamins, minerals, herbal products, and drugs prescribed by other doctors.