What effect would the presence of tetracycline in the body have on penicillin therapy?

Answer 1

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.