INFUMOX CV 228.5

Indications

• Bacterial infections
• Urinary tract infections
• Sinusitis
• Uncomplicated community-acquired pneumonia
• Salmonellosis
• Oral infections
• Lyme disease (under expert supervision)
• Acute exacerbation of bronchiectasis
• Anthrax (treatment and post-exposure prophylaxis)

Dosage

Children: 1 month–11 years: 30 mg/kg 3 times a day for 21 days; children 1–4 years: 250 mg 3 times a day; children 5–11 years: 500 mg 3 times a day.

Adults: 500 mg 3 times a day; increased if necessary up to 1 g 3 times a day in severe infections.

Mechanism of action

Amoxicillin works by inhibiting bacterial cell wall synthesis, leading to cell lysis and death. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, interfering with the transpeptidation process necessary for cell wall integrity.

Pharmacodynamics

Amoxicillin exhibits bactericidal activity against susceptible bacteria. Its action is time-dependent, meaning that its effectiveness is related to the duration of time that the drug concentration remains above the minimum inhibitory concentration (MIC) for the target pathogen.

Pharmacokinetics

Amoxicillin is well absorbed from the gastrointestinal tract, with peak plasma concentrations achieved within 1-2 hours after oral administration. It is widely distributed in body tissues and fluids, and it is excreted primarily via the kidneys. The elimination half-life is approximately 1 hour, and renal impairment may necessitate dosage adjustments.

Adverse effects

• Skin rash
• Gastrointestinal disturbances (nausea, vomiting, diarrhea)
• Allergic reactions (including anaphylaxis)
• Superinfection (due to resistant organisms)

Interactions

• Allopurinol (increases risk of skin rash)

Precautions

• History of penicillin allergy
• Renal impairment (reduce dose)
• Use with caution in patients with mononucleosis

Pregnancy

Use only if clearly needed; no adequate studies in pregnant women.

Breast-feeding

Amoxicillin is excreted in breast milk; use with caution.

Storage

Store in a cool, dry place away from direct sunlight.

Formulations

• Phenoxymethylpenicillin 250mg/5ml oral solution
• Phenoxymethylpenicillin 250 mg tablets

Indications

• Infections caused by beta-lactamase producing organisms
• Acute bacterial sinusitis
• Acute otitis media
• Community-acquired pneumonia
• Urinary tract infections
• Skin and soft tissue infections

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines.

Adults: Refer to specific prescribing guidelines or the BNF for dosing information.

Mechanism of action

Clavulanic acid irreversibly binds to the active site of beta-lactamase enzymes. By doing so, it inhibits the hydrolytic activity of these enzymes, which would otherwise inactivate beta-lactam antibiotics. This inhibition allows the co-administered antibiotics to remain effective against beta-lactamase-producing bacteria.

Pharmacodynamics

While clavulanic acid has limited standalone antibacterial activity, its role as a beta-lactamase inhibitor is critical in augmenting the efficacy of beta-lactam antibiotics. The combination of clavulanic acid with penicillins can extend the spectrum of activity against Gram-negative bacteria and certain Gram-positive bacteria that produce beta-lactamase.

Pharmacokinetics

Clavulanic acid is absorbed well after oral administration, with peak plasma concentrations occurring within 1 hour. It is distributed widely in body tissues and fluids. The drug undergoes hepatic metabolism, primarily through conjugation. The elimination half-life ranges from 1 to 2 hours, with renal excretion accounting for a significant portion of the drug's clearance.

Contra-indications

• Hypersensitivity to clavulanic acid or any component of the formulation
• Severe hepatic impairment
• History of jaundice or hepatic dysfunction associated with the use of beta-lactam antibiotics

Adverse effects

• Nausea
• Diarrhea
• Vomiting
• Rash
• Hepatic dysfunction
• Allergic reactions
• Superinfection due to prolonged use

Interactions

• May enhance the anticoagulant effect of warfarin
• Probenecid may increase plasma concentrations of clavulanic acid
• Potential interaction with other antibiotics that affect gut flora

Precautions

• Use with caution in patients with renal impairment
• Monitor liver function in patients with pre-existing liver disease
• Careful consideration in pregnant women and breastfeeding mothers
• Assess for potential allergic reactions in patients with a history of penicillin allergy

Pregnancy

Clavulanic acid should only be used during pregnancy if clearly needed. Animal studies have not demonstrated teratogenic effects, but there is limited human data.

Breast-feeding

Clavulanic acid is excreted in breast milk. Caution is advised when administering to nursing mothers, and monitoring of the infant for potential adverse effects is recommended.

Storage

Store in a cool, dry place, away from direct sunlight. Keep out of reach of children.

Formulations

• Oral tablets
• Oral suspension
• Injection

Mechanism of action

Amoxicillin competitively inhibits penicillin-binding protein 1 and other high molecular weight penicillin binding proteins. Penicillin bind proteins are responsible for glycosyltransferase and transpeptidase reactions that lead to cross-linking of D-alanine and D-aspartic acid in bacterial cell walls. Without the action of penicillin binding proteins, bacteria upregulate autolytic enzymes and are unable to build and repair the cell wall, leading to bacteriocidal action. 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/ Amoxicillin is similar to penicillin in its bactericidal action against susceptible bacteria during the stage of active multiplication. It acts through the inhibition of cell wall biosynthesis that leads to the death of the bacteria.

Pharmacodynamics

Amoxicillin competitively inhibit penicillin binding proteins, leading to upregulation of autolytic enzymes and inhibition of cell wall synthesis. Amoxicillin has a long duration of action as it is usually given twice daily. Amoxicillin has a wide therapeutic range as mild overdoses are not associated with significant toxicity. Patients should be counselled regarding the risk of anaphylaxis, _Clostridium difficile_ infections, and bacterial resistance.