In the kidneys, it is filtered out mostly by tubular secretion; some also undergoes glomerular filtration, and the rest is excreted in the feces and bile. Hetacillin and pivampicillin are ampicillin esters that have been developed to increase bioavailability. History
Ampicillin has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against gram-positive organisms such as staphylococci and streptococci. Ampicillin (originally branded as "Penbritin") also demonstrated activity against gram-negative organisms such as H. influenzae, coliforms, and Proteus spp. Cost
Ampicillin is relatively inexpensive. In the United States, it is available as a generic medication. Veterinary use
In veterinary medicine, ampicillin is used in cats, dogs, and farm animals to treat:
Anal gland infections
Cutaneous infections, such as abscesses, cellulitis, and pustular dermatitis
E. coli and Salmonella infections in cattle, sheep, and goats (oral form). Ampicillin use for this purpose had declined as bacterial resistance has increased. Mastitis in sows
Mixed aerobic–anaerobic infections, such as from cat bites
Multidrug-resistant Enterococcus faecalis and E. faecium
Prophylactic use in poultry against Salmonella and sepsis from E. coli or Staphylococcus aureus
Respiratory tract infections, including tonsilitis, bovine respiratory disease, shipping fever, bronchopneumonia, and calf and bovine pneumonia
Urinary tract infections in dogsHorses are generally not treated with ampicillin, as they have low bioavailability of beta-lactams.The half-life in animals is around that same of that in humans (just over an hour). Oral absorption is less than 50% in cats and dogs, and less than 4% in horses.
Specific populations
Ampicillin is one of the most used drugs in pregnancy, and has been found to be generally harmless both by the Food and Drug Administration in the U.S. (which classified it as category B) and the Therapeutic Goods Administration in Australia (which classified it as category A). It is the drug of choice for treating Listeria monocytogenes in pregnant women, either alone or combined with an aminoglycoside. Pregnancy increases the clearance of ampicillin by up to 50%, and a higher dose is thus needed to reach therapeutic levels.Ampicillin crosses the placenta and remains in the amniotic fluid at 50–100% of the concentration in maternal plasma; this can lead to high concentrations of ampicillin in the newborn.While lactating mothers secrete some ampicillin into their breast milk, the amount is minimal.In newborns, ampicillin has a longer half-life and lower plasma protein binding. The clearance by the kidneys is lower, as kidney function has not fully developed. Contraindications
Ampicillin is contraindicated in those with a hypersensitivity to penicillins, as they can cause fatal anaphylactic reactions. Hypersensitivity reactions can include frequent skin rashes and hives, exfoliative dermatitis, erythema multiforme, and a temporary decrease in both red and white blood cells.Ampicillin is not recommended in people with concurrent mononucleosis, as over 40% of patients develop a skin rash. Side effects
Ampicillin is comparatively less toxic than other antibiotics, and side effects are more likely in those who are sensitive to penicillins and those with a history of asthma or allergies.