1. Facts about Tetracyclines
1: Tetracyclines are broad-spectrum antibacterials effective in
the treatment of acne, Lyme disease, malaria, chlamydia,
Rickettsia infections, and syphilis.
2:They are protein synthesis inhibitors – inhibiting the 30S
ribosomal subunit – inhibiting the binding of aminoacyl-tRNA to the
mRNA translation complex.
3: Side effects include tooth discoloration and enamel
hypoplasia, hence these drugs should be avoided in children and
those who are pregnant.
4: Demeclocycline inhibits antidiuretic hormone and so is an
effective treatment option for SIADH.
5: Other side effects include photosensitivity, esophageal
irritation, and GI effects – nausea, vomiting, diarrhea.
6: Tetracyclines are usually formulated as capsules or tablets.
For this reason, they should be swallowed with a whole glass of
water while standing/sitting, to avoid any irritation to the throat.
2. 7: Tetracyclines bind to divalent ions which interferes with
absorption. They should not be taken within 2 hours of calcium,
antacids or iron.
8: Tetracyclines enhance the anticoagulant effect of
warfarin by killing normal gut flora which otherwise synthesizes
vitamin K.
9: Intracranial hypertension is a rare adverse effect that leads to
headache and visual disturbances.
10: Tetracyclines may be divided according to their half-lives:
Short-acting drugs (half-life 6-8 hours): such as lymecycline
and oxytetracycline and tetracycline (“LOT” drugs).
Intermediate-acting drugs (half-life around 12 hours): such as
demeclocycline (intermediate – demeclocycline’
Long-acting drugs (half-life 16 hours or more): such
as doxycycline & minocycline and tigecycline (“Do More Time”
drugs)
