Drug Class

Tetracyclines

Binding the 30S ribosomal subunit so tRNA cannot bring in new amino acids.

Also called tetracycline antibiotics.

Class card

Drugs: Doxycycline and Tetracycline
Used for: Chlamydia and other sexually transmitted infections
Rickettsial infections, such as spotted fevers and typhus
Acne (adjunct therapy)
Atypical pneumonia (Mycoplasma)
Known for: Permanent tooth discoloration if given under age 8
Photosensitivity (exaggerated sunburn)
Esophagitis and esophageal ulcers
Name stems: -cycline

3 cards: the class, and each drug in it.

Mechanism of action

How do tetracyclines work?

Tetracyclines bind the bacterial 30S ribosomal subunit and stop aminoacyl-tRNA from docking on the mRNA-ribosome complex, so no further amino acids are added. They are mainly bacteriostatic and broad-spectrum, including Chlamydia, Rickettsia and Mycoplasma. They form stable calcium complexes in growing bone, and metal ions in antacids and iron block their absorption.

The drugs

Tetracyclines with a card

Uses

What are tetracyclines used for?

Chlamydia and other sexually transmitted infections
Rickettsial infections, such as spotted fevers and typhus
Acne (adjunct therapy)
Atypical pneumonia (Mycoplasma)
Early Lyme disease (doxycycline)
Malaria prevention for travelers (doxycycline)

Side effects

Side effects of tetracyclines

Permanent tooth discoloration if given under age 8Known for
Photosensitivity (exaggerated sunburn)Known for
Esophagitis and esophageal ulcersKnown forSerious
Nausea and vomiting
Diarrhea
Raised pressure in the skull (pseudotumor cerebri)Serious
Liver toxicitySerious
Candida overgrowth (thrush), mainly anogenital
C. difficile colitisSerious
Severe skin reactions and fixed drug eruptionsSerious

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

Watch for

Cautions

Avoid in the second half of pregnancy and in children under 8 (teeth stain, bone growth slows), except for serious infections such as RMSF.
Antacids, calcium, magnesium, iron, zinc and bismuth bind them in the gut and cut their absorption.
Esophageal ulcers mostly follow tablets taken just before lying down.
They can increase warfarin's effect, and with isotretinoin the risk of raised intracranial pressure rises.

Remember them

A way to remember them

TEETH

T: Tooth discoloration in children under 8
E: Esophageal ulcers if taken just before lying down
E: Exaggerated sunburn (photosensitivity)
T: Thrush from Candida overgrowth
H: High pressure in the skull (pseudotumor cerebri)

TEETH fits a class best known for staining developing teeth; tetracyclines also bind calcium wherever bone is forming.

Written for biofideX

Name stems

-cycline means tetracycline antibiotic
Doxycycline, minocycline and tigecycline share it. Anthracycline anticancer drugs such as doxorubicin end in -rubicin instead.
Every drug name stem

Don't mix them up

Classes easily confused with these

Sources

Checked against

Written for biofideX in plain words, after checking these references:

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.

Practice them

Antibiotics: protein synthesis

Practice tetracyclines with the other classes in this group: what each drug is, how it works, what it treats and what it's known for.

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