MOXAFORTE 500 250/250MG CAPSULES

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

• Bacterial infections due to beta-lactamase-producing staphylococci
• Cellulitis
• Endocarditis (in combination with other antibiotics)
• Osteomyelitis
• Impetigo
• Severe infections in cystic fibrosis patients

Dosage

Children: For neonates up to 7 days

Adults: The usual adult dosage for severe infections is 1 g every 6 hours, with a maximum of 4 g per day. For specific conditions, such as Staphylococcal infections, the dose may vary; consult the BNF for detailed guidance.

Mechanism of action

Flucloxacillin binds to specific penicillin-binding proteins (PBPs) within the bacterial cell wall, inhibiting the final stages of cell wall synthesis. This action leads to cell lysis, facilitated by bacterial autolytic enzymes. It may also interfere with autolysin inhibitors, enhancing its bactericidal effect.

Pharmacodynamics

As a beta-lactam antibiotic, flucloxacillin exhibits bactericidal activity, primarily against gram-positive bacteria, including Staphylococcus aureus. It is effective against both aerobic and anaerobic bacteria, and its activity results from the inhibition of peptidoglycan synthesis in the bacterial cell wall. Flucloxacillin demonstrates resistance to hydrolysis by certain beta-lactamases, allowing it to treat infections caused by resistant strains effectively.

Pharmacokinetics

Flucloxacillin is absorbed well when administered orally, with peak plasma concentrations typically occurring 1-2 hours post-dose. It is distributed widely in body tissues and fluids, including bone and bile. The drug is primarily excreted via the kidneys, with around 70-90% of an administered dose excreted as unchanged drug in the urine. Its half-life is approximately 0.5 to 1 hour, necessitating multiple daily doses for effective treatment.

Adverse effects

• Vulvo-vaginal fungal infection
• Dizziness
• Fatigue
• Gastrointestinal discomfort
• Gastrointestinal disorders
• Headache
• Oral ulceration
• Vertigo

Interactions

• Refer to Appendix 1: penicillins (severe infection)

Precautions

• Avoid in acute porphyrias
• Monitor liver and renal function tests required in long-term use

Pregnancy

Not known to be harmful, but the manufacturer advises avoidance.

Breast-feeding

Trace amount in milk, but appropriate to use.

Storage

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

Formulations

• Tablets
• Injectable solution

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.

Mechanism of action

By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, flucloxacillin 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 flucloxacillin interferes with an autolysin inhibitor.

Pharmacodynamics

Flucloxacillin 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. Flucloxacillin has <i>in vitro</i> activity against gram-positive and gram-negative aerobic and anaerobic bacteria. The bactericidal activity of Flucloxacillin results from the inhibition of cell wall synthesis and is mediated through flucloxacillin binding to penicillin binding proteins (PBPs). Flucloxacillin is stable against hydrolysis by a variety of beta-lactamases, including penicillinases, and cephalosporinases and extended spectrum beta-lactamases.