MEDIBRITIN CAPSULES 250MG

Indications

• Bacterial infections
• Listerial meningitis
• Bronchitis
• Urinary tract infections
• Community-acquired pneumonia
• Salmonellosis

Dosage

Children: Refer to the BNF for Children for specific dosing: Neonate up to 7 days: 30 mg/kg every 12 hours; Neonate 7 to 20 days: 30 mg/kg every 8 hours; Neonate 21 to 28 days: 30 mg/kg every 6 hours.

Adults: 500 mg to 1 g every 6 hours, depending on the severity of the infection.

Mechanism of action

Ampicillin works by inhibiting bacterial cell wall synthesis, leading to cell lysis and death in susceptible bacteria.

Pharmacodynamics

Ampicillin exhibits bactericidal activity against a broad spectrum of gram-positive and some gram-negative bacteria, including Streptococcus spp., Enterococcus spp., and certain E. coli strains.

Pharmacokinetics

Ampicillin is well absorbed from the gastrointestinal tract, with a bioavailability of approximately 50-70%. It is distributed widely in body tissues and fluids, including the central nervous system. It is primarily eliminated by the kidneys through glomerular filtration and tubular secretion.

Adverse effects

• Colitis haemorrhagic
• Skin rash

Interactions

• Allopurinol (increases risk of skin rash)

Precautions

• Caution in renal impairment
• Potential for electrolyte accumulation with intravenous use

Pregnancy

Not known to be harmful.

Breast-feeding

Trace amounts in milk, but appropriate to use.

Storage

Store in a cool, dry place, protected from light.

Formulations

• Ampicillin 500 mg capsules
• Ampicillin 125 mg/5 ml oral suspension
• Ampicillin 25 mg per 1 ml oral suspension
• Ampicillin powder for injection

Mechanism of action

By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, Ampicillin inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that Ampicillin interferes with an autolysin inhibitor. SINCE PENICILLIN HAS NO EFFECT ON EXISTING CELL WALLS, BACTERIA MUST BE MULTIPLYING FOR BACTERICIDAL ACTION OF PENICILLIN TO BE MANIFEST. /PENICILLINS/ The penicillins and their metabolites are potent immunogens because of their ability to combine with proteins and act as haptens for acute antibody-mediated reactions. The most frequent (about 95 percent) or "major" determinant of penicillin allergy is the penicilloyl determinant produced by opening the beta-lactam ring of the penicillin. This allows linkage of the penicillin to protein at the amide group. "Minor" determinants (less frequent) are the other metabolites formed, including native penicillin and penicilloic acids. /Penicillins/ Bactericidal; inhibit bacterial cell wall synthesis. Action is dependent on the ability of penicillins to reach and bind penicillin binding proteins located on the inner membrane of the bacterial cell wall. Penicillin binding proteins (which include transpeptidases, carboxypeptidases, and endopeptidases) are enzymes that are involved in the terminal stages of assembling the bacterial cell wall and in reshaping the cell wall during growth and division. Penicillins bind to, and inactivate, penicillin binding proteins, resulting in the weakening of the bacterial cell wall and lysis. /Penicillins/

Pharmacodynamics

Ampicillin is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually gram-positive, organisms. The name "penicillin" can either refer to several variants of penicillin available, or to the group of antibiotics derived from the penicillins. Ampicillin has <i>in vitro</i> activity against gram-positive and gram-negative aerobic and anaerobic bacteria. The bactericidal activity of Ampicillin results from the inhibition of cell wall synthesis and is mediated through Ampicillin binding to penicillin binding proteins (PBPs). Ampicillin is stable against hydrolysis by a variety of beta-lactamases, including penicillinases, and cephalosporinases and extended spectrum beta-lactamases.