Antibiotics

4 Antibiotics

Antibiotics are produced by certain bacteria or fungi that interfere with or prevent the growth of other bacteria/fungi. They are used in infection or as prophylaxis, e.g. in cases of spontaneous rupture of membranes longer than 24 hours, or in lower-segment caesarean section.

The student should be aware of:

BP
Metronidazole
Proprietary
Flagyl® (Winthrop Pharmaceuticals UK Ltd) (Aventis UK Ltd), Metrolyl® (Sandoz Ltd), Flagyl® injection (Winthrop Pharmaceuticals UK Ltd), metronidazole (non-proprietary, see BNF for details)
Group
Antimicrobial
Uses/indications
Treatment of anaerobic infection with a wide range of activity, prophylaxis in surgery (anaerobic bacteria and anaerobic streptococci), clostridium, Trichomonas vaginalis, Eubacterium, Gardnerella vaginalis, puerperal sepsis, bacterial vaginosis, gingivitis
Type of drug
POM
Presentation
Tablets, suspension, suppositories, pre-prepared IV injections and infusions
Dosage
Oral: stat 800 mg then 400–500 mg t.d.s.IV: 500 mg t.d.s.P.R.: 1 g t.d.s. for 3 days max, then 1 g b.d. treatment of bacterial vaginosis as for oral, or 2 g single dose
Route of admin
Oral, P.R., IV, IM
Contraindications
In pregnancy and breastfeeding avoid high dosage, avoid alcohol, known hypersensitivity to metronidazole
Side effects
Unpleasant taste in mouth, furry tongue, nausea, vomiting, rashes, headache, drowsiness, dizziness, dark urine and, very rarely, angio-oedema
Interactions
Alcohol – disulfiram-like reaction – avoid during treatment and for 48 h post courseAntacids – cimetidine inhibits the metabolism of metronidazoleAnticoagulants – enhances the effect of warfarin but no interaction with heparinAntiepileptics – inhibits the metabolism of phenytoin; phenobarbital accelerates metabolism of metronidazole
Oestrogens – reduces the effect of the combined oral contraceptive pill
Pharmacodynamic properties
Antimicrobial effective against a wide range of infections with antiprotozoal and antibacterial actions
Fetal risk
Avoid high-dose regimens; use in first trimester can cause midline facial defects, cardiac defects, genital defects and limb defects, but has been used with little effect in last two trimesters
Breastfeeding
Significant amounts secreted; avoid large single doses
BP
Erythromycin stearate
Proprietary
Erythrocin® (Amdipharm PLC)Erythromycin (non-proprietary, see BNF for details)
Group
Antibiotic, macrolide
Uses/indications
Used in penicillin-sensitive clients, penicillin-resistant organisms, syphilis, chlamydia, gonorrhoea, respiratory infection, treatment of infection sensitive to erythromycin, prophylaxis in management of pre-term rupture of membranes
Type of drug
POM
Presentation
Tablets, capsules, powder for reconstitution, granules, suspension
Dosage
1–2 g/day in even doses, depending on the severity of infectionOral: 250–500 mg q.d.s. or 0.5–1 g b.d.
Syphilis/chlamydia: 500 mg q.d.s. for 14 days; IV: 25–50 mg/kg daily or 1–2 g in 6 even doses
Route of admin
Oral, IV
Contraindications
Hypersensitivity, hepatic dysfunction
Side effects
Nausea, vomiting, diarrhoea, fever, skin eruptions, urticaria, rashes, cardiac arrhythmias; in large doses – reversible hearing loss, hepatic dysfunction, thrombophlebitis following IV administration, allergic response rare with mild anaphylaxis
Interactions
Anticoagulants – effect of warfarin enhancedAntihistamines – inhibits the metabolism of terfenadine, causing dangerous cardiac arrhythmiasCisapride – can cause cardiotoxicity and arrhythmiasErgotamines – acute ergot toxicity, rapid peripheral vasospasm and dysaesthesiaTheophylline – inhibition of metabolism of theophylline
Pharmacodynamic properties
Antimicrobial that attaches to a subunit of susceptible organisms and suppresses protein synthesis, destroying cell wall stability and making them vulnerable to attack. Active against both Gram-positive and Gram-negative bacteria, mycoplasms, treponema, chlamydia and gonorrhoea
Fetal risk
Crosses the placental barrier but not in appreciable quantities; fetal concentrations have found to be low, with no reports of congenital defects located except in animal studies – cardiovascular malformations if used in early pregnancy. However, manufacturers advise that, if used to treat maternal syphilitic infection during pregnancy, the infant may be born with congenital syphilis and should receive penicillin treatment following birth
Breastfeeding
Secreted in only small amounts in breast milk – considered safe with no ill effects reported, although manufacturers advise avoidance
BP
Cefuroxime
Proprietary
Cefuroxime (Sandoz Ltd); Zinacef (GlaxoSmithKlein UK),Cephradine (non-proprietary, see BNF for details)
Group
Antibiotic – cephalosporin
Uses/indications
Against both Gram-positive and Gram-negative bacteria, prophylaxis with LSCS, UTI, respiratory infections
Type of drug
POM
Presentation
Capsules, syrup, powder for reconstitution
Dosage
Oral: 250–500 mg b.d. or 0.5–1 g b.d.IM, IV: 500 mg–1 g q.d.s. given over 3–5 min
Route of admin
Oral, IM, IV
Contraindications
Renal dysfunction, known hypersensitivity to cephalosporins, caution in penicillin hypersensitivity
Side effects
Nausea, diarrhoea and hypersensitivity – usually mild, headache, dizziness, dyspnoea
Interactions
Nil specific to cephradine:Anticoagulants – effect of warfarin enhancedUricosurics – excretion is reduced by probenecidOestrogens – reduces the effect of the combined oral contraceptive pill
Pharmacodynamic properties
Broad-spectrum bactericidal drug active against Gram-positive organisms, e.g. staphylococci, streptococci, Streptococcus pyogenes, Streptococcus pneumoniae, and Gram-negative organisms such as Escherichia coli, Haemophilus influenzae, salmonella. Highly active against penicillinase-producing staphylococci. e.g. Saureus
Fetal risk
No reports of congenital defects located, although manufacturers advise safety not established
Breastfeeding
Considered safe, although manufacturers advise caution – as for amoxicillin
Jul 11, 2016 | Posted by in MIDWIFERY | Comments Off on Antibiotics

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