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Teratogenic antibiotics
1.
2. Key points
WHAT IS TERATOGEN AND ITS MECHNISM ?
WHAT IS TRIMESTER ?
WHAT ARE THE FDA PREGNANCY CATEGORIS ?
WHAT ARE TERATOGENIC ANTIBIOTICS ?
3. Teras-”monster” Gensis-”producing”
A teratogen is defined as any agent that results in structural
or functional abnormalities (malformation ) in the fetus, or in
the child after birth, as a consequence of maternal exposure
during pregnancy. Classes of teratogens include radiation,
maternal infections, chemicals, and drugs
Birth defects are known to occur in 3-5% of all newborns.
They can do direct damage to the fetus, causing abnormal
development.
They can compromise the function of the placenta, often by
constricting blood vessels and reducing the supply of
oxygen and nutrients from the mother to the fetus. This
can lead to underdevelopment or low birth weight, which
are risk factors for birth defects.
They can trigger forceful uterine contractions, potentially
injuring the fetus or prompting premature birth.
4. MECHANISM OF TERATOGENESIS
• Direct effect on maternal tissue with secondary effect on fetus
• Indirect-such as interfering with O2 or nutrients.
• Teratogenesis maybe direct-malformations of structures. e.g.
i. Vitamin A analogs (isotretinoin,etretinate)
ii. Deficiency of a critical substance (folic acid causing neural tube
defects)
iii. Continues exposure to teratogen may produce cumulative
effect (Fetal Alcohol Syndrome)
5. • a period of three months,
especially as a division of the
duration of pregnancy.
• Pregnancy has three trimesters,
each of which is marked by
specific fetal developments .
TRIMESTER
6. FIRST TRIMESTER
• In the first four weeks from conception, fetal growth of the ovum
begins with development of the spinal cord, nervous system,
gastrointestinal system, heart and lungs. By eight weeks, in the
embryonic stage, the face is forming, arms and legs move, the
baby's heart begins beating and the brain and other organs form.
By 12 weeks, the baby, now called a fetus, grows to 3 inches long
and weighs 1 ounce , can move fingers and toes. Fingerprints are
present. The baby smiles, frowns, sucks, swallows and urinates. The
sex of the baby can be discerned by this time.
7. SECOND TRIMESTER
• During the second three months of pregnancy, the baby kicks, can
hear and has a strong grip. At 16 weeks a strong heartbeat is
evident. The skin is transparent and fingernails and toenails form.
The baby can roll over in the amniotic fluid. At 20 weeks, the
heartbeat can be heard with a stethoscope. The baby has hair,
eyelashes and eyebrows. He can suck his thumb and may have
hiccups. By 24 weeks, the baby is 11 to 14 inches long and weighs 1
to 1 1/2 pounds. His skin is covered with a protective coating, his
eyes are open and meconium, which will be his first bowel
movement after birth ( first stool ) , is collecting in his colon.
8. THIRD TRIMESTER
• The baby is very active at 28 weeks and initial breathing movements
begin. The baby is adding body fat. By 32 weeks, the baby
experiences periods of sleep and wakefulness and responds to
sounds. A six months supply of iron is accumulating in the liver. By
36 to 38 weeks the baby is 19 or more inches long and weighs 6
pounds or more. At this point the baby is less active and gains
immunities from the mother.
12. CATEGORY A
• failed to
demonstrate
a risk to the
fetus in the
first
trimester of
pregnancy
• no evidence
of risk in
later
trimesters
CATEGORY C
• shown an
adverse effect
on the fetus
• no adequate
and well-
controlled
studies in
humans
• potential
benefits may
warrant the
use of drug
despite
potential risks.
CATEGORY D
• positive
evidence of
human fetal
risk based on
adverse
reaction data
• potential
benefits may
warrant use of
the drug in
pregnant
women despite
potential risks
CATEGORY B
• failed to
demonstrate
a risk to the
fetus
• no adequate
and well-
controlled
studies in
pregnant
women.
CATEGORY X
• demonstrates
fetal
abnormalities
• positive
evidence of
human fetal risk
based on
adverse
reaction data
• the risks
involved in use
of the drug in
pregnant
women
CATEGORY N
• FDA has
not
classified
the drug.
13. TETRACYCLINE
Pregnancy category - D
Trimesters of risk - Second and third
• Protein synthesis inhibitor
• Inhibit the binding of aminoacyl-tRNA to the mRNA- ribosomes complex
Aminoacyl-tRNA mRNA-ribosomes complex
by binding to the 30S ribosomal subunit in mRNA translation complex
14. SIDE EFFECTS
• IN PREGNANCY…..
Dental discoloration in children
Maternal hepatotoxicity with large parenteral doses
15. CHLORAMPHENICOL
• category C
• Bacteriostatic drug that stop bacterial growth by inhibiting protein
synthesis
• Prevent protein chain elongation by inhibiting peptidyl transferase
activity of bacterial chromosome
• Intravenous chloramphenicol use has been associated with Gray
Baby syndrome
This occur in newborn infants because they liver enzymes not yet
fully developed
chloramphenicol remains unmetabolized in body
16. ADVERSE EFFECTS
• Hypotension
• Cyanosis
The condition can be prevented by using the drug at
recommended doses & monitoring blood levels
Gray Baby Syndrome
17. AMINOGLYCOSIDES
•tobramycin, Gentamicin , amikacin, netilmicin, streptomycin,
kanamycin are category D
• because eighth cranial nerve damage has been reported in children
whose mothers received streptomycin as long-term therapy for
tuberculosis. No cases of deafness have been reported for
gentamicin, tobramycin, or amikacin. However, there is still
potential for ototoxicity, so these agents should be avoided during
pregnancy. If gentamicin is used, patients should be monitored
using serum gentamicin concentrations (concentrations in amniotic
fluid range from 30% to 50% of maternal concentrations). Renal
function also should be assessed periodically by monitoring serum
creatinine. Data regarding safety of once-daily
18. SULFONAMIDE & TRIMETHOPRIM
• Category c
• Sulfonamides have a bacteriostatic effect by inhibiting bacterial
folic acid synthesis , used in urinary tract infections .
• Trimethoprim binds to dihydrofolate redustase and inhibit
reduction of DHF to THF
• Sulfamethoxazole inhibit dihydrofolate synthetase
20. Macrolides
• Erythromycin crosses the placenta, but fetal concentrations are
generally low due to erratic absorption from the maternal
gastrointestinal tract and unpredictable transplacental passage.
Erythromycin is also a category B drug -- the base and succinate
forms are considered safe for use during pregnancy. However,
erythromycin estolate should not be used during pregnancy
because it has been associated with a 10% to 15% incidence of
reversible hepatotoxicity in mothers during the second half of
pregnancy.
• Less is known about the newer macrolides. Azithromycin (category
B) has shown no teratogenic effects in animal studies, but there are
no adequate controlled studies in pregnant women.
Clarithromycin (category C ) has been shown to cause teratogenic
effects in animals, but its effects in humans are unknown.
21. Fluoroquinolones
• category C
• not recommended for use in pregnancy because they have been
shown to cause arthropathy in weight-bearing joints as well as
noninflammatory joint effusions, fluid-filled blisters, fissures,
erosions, and clusters of chondrocytes in immature animals. It is
hypothesized that the fluoroquinolones may impair skeletal
development in fetuses and infants, especially in their weight-
bearing joints.
• One study of 38 patients exposed to norfloxacin and ciprofloxacin
during pregnancy failed to show any adverse effects on the
musculoskeletal system. The majority of women took these agents
during the first trimester of pregnancy. Assessment was based on
information obtained about the child from mothers and physicians;
however, no diagnostic procedures, such as MRI, were done.
22. Griseofulvin
• Category C
• In animal experiments griseofulvin is teratogenic and, at high doses,
• cancerogenic. It crosses the placenta at term. One publication,
• based on birth defects data, reported two pairs of conjoined
• twins after the use of griseofulvin in early pregnancy
• As griseofulvin is not used to treat life-threatening fungal
infections, its application in pregnancy should be avoided. If
treatment took place in the first trimester, a detailed ultrasound
examination should be offered to ascertain the normal
development of the fetus
23. Treatment and prevention
• The best course is to prevent teratogen exposure, or reduce the
exposure as much as possible.
• Prevention is complicated because very often women may not
realize they are pregnant until the middle of the period of
susceptibility.
