What effect would the presence of tetracycline in the body have on penicillin therapy?
The presence of tetracycline in the body will greatly inhibit
the effectiveness of the penicillin.
Most antibiotics fall into two groups: bacteriostatic, and
bacteriocidal. Penicillin is bactericidal, and tetracycline is
bacteristatic. Bactericidals kills the bacterium whereas
bacteristatics stop the bacterium from growing, but it is still
alive, so once the antibiotic is taken away the bacteria will start
growing again.
Penicillin requires that the bacterium continue to grow in order
to kill the bacterium. Because penicillin stops to the cell wall
from growing, but the bacteria continues to grow causing it to
erupt out of the cell, killing it.
Since the tetracycline effectively keeps the bacterium from
growing, giving the bodies own immune system the opportunity to
kill it, the penicillin will be rendered somewhat useless and
therefore these two therapies should not be combined.
You should always tell your doctor, and your pharmacist about
any and all medications you are taking, as they can point out
problems like this easily.