Tetracyclines are a class of broad-spectrum antibiotics used to treat a wide variety of bacterial infections. Discovered in the 1940s, these drugs are derived from Streptomyces bacteria and are valued for their effectiveness against many different microorganisms. This action allows the body’s own immune system to overcome the infection.
Common Tetracycline Medications
The tetracycline family includes several distinct medications, some of which have been in use for decades while others are more recent developments. The original drug in this class is tetracycline itself. Over time, semi-synthetic versions were created that are better absorbed by the body and can be taken less frequently.
Among the most common is doxycycline, recognized by brand names such as Vibramycin and Monodox. It is prescribed due to its convenient once or twice-daily dosing and its ability to be taken with food, unlike some other tetracyclines. Another prevalent example is minocycline, known under brand names like Minocin and Solodyn, which is used for treating acne.
More recent additions to the tetracycline class show how the drugs have been refined for specific purposes. Sarecycline, sold as Seysara, is a newer, narrow-spectrum antibiotic primarily for acne, which may cause fewer gastrointestinal side effects. Omadacycline (Nuzyra) and Eravacycline (Xerava) are newer, potent options developed to combat infections caused by bacteria that have become resistant to older antibiotics.
Conditions Treated by Tetracyclines
Tetracycline antibiotics are versatile, used for a wide range of conditions affecting different parts of the body, from skin and respiratory infections to diseases transmitted by ticks. Their broad-spectrum activity makes them effective against a diverse array of bacteria.
One of the most well-known uses for this class of antibiotics is in dermatology, particularly for managing moderate to severe acne and rosacea. For these conditions, the antibiotics work not only by reducing bacteria on the skin but also by exerting anti-inflammatory effects. They are also prescribed for other skin infections.
Tetracyclines are a primary treatment for several tick-borne illnesses. They are considered a first-line therapy for:
- Lyme disease
- Rocky Mountain spotted fever
- Ehrlichiosis
- Anaplasmosis
Beyond skin and tick-related diseases, these antibiotics are used for respiratory infections like atypical pneumonia and bronchitis. They are also effective against certain sexually transmitted infections, including chlamydia, and can be part of treatment regimens for stomach ulcers caused by H. pylori bacteria or for malaria prevention.
How Tetracyclines Work Against Bacteria
Tetracyclines stop bacterial growth by interfering with a fundamental cellular process: protein synthesis. These antibiotics are able to pass through the bacterial cell membrane to reach the cytoplasm inside. Once inside, they target the cellular machinery responsible for building proteins, effectively shutting down production. This mechanism is what makes them bacteriostatic, halting replication and spread.
The specific target within the bacterial cell is the ribosome, which acts as the assembly site for proteins. Tetracyclines bind to a part of the ribosome called the 30S ribosomal subunit. This binding physically blocks the next step in protein assembly, preventing the attachment of aminoacyl-tRNA, the molecule that carries the amino acid building blocks. By obstructing this site, the antibiotic prevents the peptide chain from growing.
This process effectively gums up the works of the bacteria’s internal factory. Without the ability to produce new proteins, the bacteria cannot perform functions needed for growth, repair, or reproduction. While human cells also have ribosomes, tetracyclines do not accumulate in them in the same way, allowing the drug to target bacteria with minimal impact on human cells.
Key Side Effects and Safety Considerations
Tetracyclines can cause a range of side effects. The most frequently reported issues are gastrointestinal, such as nausea, vomiting, and diarrhea. Another common concern is photosensitivity, which is an increased sensitivity to sunlight that can result in a severe sunburn reaction. Patients are often advised to use extra sun protection while taking these medications.
Significant precautions are necessary for specific populations. Tetracyclines are not prescribed for pregnant women or children under the age of eight. This is because the drug can bind to calcium in developing bones and teeth, potentially causing permanent tooth discoloration and affecting bone growth in a fetus or young child.
Interactions with certain foods and other medications can also occur. Tetracyclines can bind to minerals like calcium, iron, magnesium, and aluminum. Taking the antibiotic with dairy products, antacids, or supplements containing these minerals can prevent the drug from being properly absorbed into the bloodstream, making it less effective. It is recommended to take tetracyclines at least one hour before or two hours after consuming such products.