Drug reference
Tinidazole is an antimicrobial drug with high activity against anaerobic bacteria and protozoa; it has a longer duration of action than metronidazole. The penicillins are bactericidal and act by interfering with bacterial cell wall synthesis. They diffuse well into body tissues and fluids, but penetration into the cerebrospinal fluid is poor except when the meninges are inflamed. They are excreted in the urine in therapeutic concentrations.
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Anaerobic infections ▶BY MOUTH ▶Adult: Initially 2 g, followed by 1 g daily usually for 5–6 days, alternatively 500 mg twice daily usually for 5–6 days Bacterial vaginosis | Acute ulcerative gingivitis ▶BY MOUTH ▶Adult: 2 g for 1 single dose Abdominal surgery prophylaxis ▶BY MOUTH ▶Adult: 2 g for 1 single dose, to be administered approximately 12 hours before surgery Intestinal amoebiasis ▶BY MOUTH ▶Child 1 month–11 years: 50–60 mg/kg once daily (max. per dose 2 g) for 3 days ▶Child 12–17 years: 2 g once daily for 2–3 days ▶Adult: 2 g once daily for 2–3 days Amoebic involvement of liver ▶BY MOUTH ▶Child 1 month–11 years: 50–60 mg/kg once daily (max. per dose 2 g) for 5 days ▶Child 12–17 years: 1.5–2 g once daily for 3–6 days ▶Adult: 1.5–2 g once daily for 3–6 days Urogenital trichomoniasis | Giardiasis ▶BY MOUTH ▶Child 1 month–11 years: 50–75 mg/kg (max. per dose 2 g) for 1 single dose, dose may be repeated once if necessary ▶Child 12–17 years: 2 g for 1 single dose, dose may be repeated once if necessary ▶Adult: 2 g for 1 single dose Helicobacter pylori eradication ▶BY MOUTH ▶Adult: (consult local protocol)
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History of allergy
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The most important side-effect of the penicillins is hypersensitivity which causes rashes and anaphylaxis and can be fatal. Allergic reactions to penicillins occur in 1–10% of exposed individuals; anaphylactic reactions occur in fewer than 0.05% of treated patients. Patients with a history of atopic allergy (e.g. asthma, eczema, hay fever) are at a higher risk of anaphylactic reactions to penicillins. Individuals with a history of anaphylaxis, urticaria, or rash immediately after penicillin administration are at risk of immediate hypersensitivity to a penicillin; these individuals should not receive a penicillin. Individuals with a history of a minor rash (i.e. non-confluent, non-pruritic rash restricted to a small area of the body) or a rash that occurs more than 72 hours after penicillin administration are probably not allergic to penicillin and in these individuals a penicillin should not be withheld unnecessarily for serious infections; the possibility of an allergic reaction should, however, be borne in mind. Other beta-lactam antibiotics (including cephalosporins) can be used in these patients. Patients who are allergic to one penicillin will be allergic to all because the hypersensitivity is related to the basic penicillin structure. Patients with a history of immediate hypersensitivity to penicillins may also react to the cephalosporins and other beta-lactam antibiotics, they should not receive these antibiotics. If a penicillin (or another beta-lactam antibiotic) is essential in an individual with immediate hypersensitivity to penicillin then specialist advice should be sought on hypersensitivity testing or using a beta-lactam antibiotic with a different structure to the penicillin that caused the hypersensitivity. ANTIBACTERIALS › PENICILLINS, ANTIPSEUDOMONAL WITH BETA- LACTAMASE INHIBITOR eiiii F 575
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→Appendix 1: tinidazole
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▶Common or very common Abdominal pain. appetite decreased. diarrhoea. headache. nausea. skin reactions. vertigo. vomiting ▶Frequency not known Angioedema. ataxia. dizziness. fatigue. flushing. leucopenia. oral disorders. peripheral neuropathy. seizure. sensation abnormal. taste altered. tongue discolouration. urine discolouration ▶Common or very common Diarrhoea. hypersensitivity. nausea. skin reactions. thrombocytopenia. vomiting ▶Uncommon Antibiotic associated colitis. leucopenia ▶Rare or very rare Agranulocytosis. angioedema. haemolytic anaemia. hepatic disorders. nephritis tubulointerstitial. seizure. severe cutaneous adverse reactions (SCARs) SIDE-EFFECTS, FURTHER INFORMATION Diarrhoea frequently occurs during oral penicillin therapy. It is most common with broad-spectrum penicillins, which can cause antibiotic-associated colitis.
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Manufacturer advises avoid in first trimester.
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Present in milk—manufacturer advises avoid breast-feeding during and for 3 days after stopping treatment.
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Clinical and laboratory monitoring advised if treatment exceeds 10 days.
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There can be variation in the licensing of different medicines containing the same drug. Tablet CAUTIONARY AND ADVISORY LABELS 4, 9, 21, 25 ▶Fasigyn (Pfizer Ltd) Tinidazole 500 mg Fasigyn 500mg tablets | 16 tablet P £11.04 DT = £11.04 ANTIBACTERIALS › PENICILLINS Penicillins Benzylpenicillin and phenoxymethylpenicillin Benzylpenicillin sodium p. 577 (Penicillin G) remains an important and useful antibiotic but is inactivated by bacterial beta-lactamases. It is effective for many streptococcal (including pneumococcal), gonococcal, and meningococcal infections and also for anthrax, diphtheria, gas-gangrene, and leptospirosis. Pneumococci, meningococci, and gonococci which have decreased sensitivity to penicillin have been isolated; benzylpenicillin sodium is no longer the drug of first choice for pneumococcal meningitis. Although benzylpenicillin sodium is effective in the treatment of tetanus, metronidazole p. 572 is preferred. Benzylpenicillin is inactivated by gastric acid and absorption from the gastro-intestinal tract is low; therefore it must be given by injection. Benzathine benzylpenicillin p. 577 is used for the treatment of early syphilis and late latent syphilis; it is given by intramuscular injection. Phenoxymethylpenicillin p. 578 (Penicillin V) has a similar antibacterial spectrum to benzylpenicillin sodium, but is less active. It is gastric acid-stable, so is suitable for oral administration. It should not be used for serious infections because absorption can be unpredictable and plasma concentrations variable. It is indicated principally for respiratory-tract infections in children, for streptococcal tonsillitis, and for continuing treatment after one or more injections of benzylpenicillin sodium when clinical response has begun. It should not be used for meningococcal or gonococcal infections. Phenoxymethylpenicillin is used for prophylaxis against streptococcal infections following rheumatic fever and against pneumococcal infections following splenectomy or in sickle-cell disease. Penicillinase-resistant penicillins Most staphylococci are now resistant to benzylpenicillin because they produce penicillinases. Flucloxacillin p. 586, however, is not inactivated by these enzymes and is thus effective in infections caused by penicillin-resistant staphylococci, which is the sole indication for its use. Flucloxacillin is acid-stable and can, therefore, be given by mouth as well as by injection. Flucloxacillin is well absorbed from the gut. Temocillin p. 587 is active against Gram-negative bacteria and is stable against a wide range of beta-lactamases. It should be reserved for the treatment of infections caused by beta-lactamase-producing strains of Gram-negative bacteria, including those resistant to third-generation cephalosporins. Temocillin is not active against Pseudomonas aeruginosa or Acinetobacter spp. Broad-spectrum penicillins Ampicillin p. 581 is active against certain Gram-positive and Gram-negative organisms but is inactivated by penicillinases including those produced by Staphylococcus aureus and by common Gram-negative bacilli such as Escherichia coli. Almost all staphylococci, approx. 60% of E. coli strains and approx. 20% of Haemophilus influenzae strains are now resistant. The likelihood of resistance should therefore be considered before using ampicillin for the ‘blind’ treatment of infections; in particular, it should not be used for hospital patients without checking sensitivity. Ampicillin is well excreted in the bile and urine. It is principally indicated for the treatment of exacerbations of chronic bronchitis and middle ear infections, both of which may be due to Streptococcus pneumoniae and H. influenzae, and for urinary-tract infections. Ampicillin can be given by mouth but less than half the dose is absorbed, and absorption is further decreased by the presence of food in the gut. Maculopapular rashes commonly occur with ampicillin (and amoxicillin p. 579) but are not usually related to true penicillin allergy. They almost always occur in patients with glandular fever; broad-spectrum penicillins should not therefore be used for ‘blind’ treatment of a sore throat. The risk of rash is also increased in patients with acute or chronic lymphocytic leukaemia or in cytomegalovirus infection. Amoxicillin is a derivative of ampicillin and has a similar antibacterial spectrum. It is better absorbed than ampicillin when given by mouth, producing higher plasma and tissue concentrations; unlike ampicillin, absorption is not affected by the presence of food in the stomach. Amoxicillin is also used for the treatment of Lyme disease. Co-amoxiclav p. 582 consists of amoxicillin with the betalactamase inhibitor clavulanic acid. Clavulanic acid itself has no significant antibacterial activity but, by inactivating beta-lactamases, it makes the combination active against beta-lactamase-producing bacteria that are resistant to amoxicillin. These include resistant strains of Staph. aureus, E. coli, and H. influenzae, as well as many Bacteroides and Klebsiella spp. Co-amoxiclav should be reserved for infections likely, or known, to be caused by amoxicillin- resistant beta-lactamase-producing strains. A combination of ampicillin with flucloxacillin (as co- fluampicil p. 582 is available to treat infections involving either streptococci or staphylococci. Antipseudomonal penicillins Piperacillin, a ureidopenicillin, is only available in combination with the beta-lactamase inhibitor tazobactam. Ticarcillin, a carboxypenicillin, is only available in combination with the beta-lactamase inhibitor clavulanic acid. Both preparations have a broad spectrum of activity against a range of Gram-positive and Gram-negative bacteria, and anaerobes. Piperacillin with tazobactam p. 576 has activity against a wider range of Gram-negative organisms than ticarcillin with clavulanic acid p. 576 and it is more active against Pseudomonas aeruginosa. These antibacterials are not active against MRSA. They are used in the treatment of septicaemia, hospital-acquired pneumonia, and complicated infections involving the urinary tract, skin Infection and soft tissues, or intra-abdomen. For severe pseudomonas infections these antipseudomonal penicillins can be given with an aminoglycoside (e.g. gentamicin p. 545) since they have a synergistic effect. Mecillinams Pivmecillinam hydrochloride p. 585 has significant activity against many Gram-negative bacteria including Escherichia coli, klebsiella, enterobacter, and salmonellae. It is not active against Pseudomonas aeruginosa or enterococci. Pivmecillinam hydrochloride is hydrolysed to mecillinam, which is the active drug. Penicillins f
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Initially 2 g, followed by 1 g daily usually for
First-line fragment. Read the complete Indications and Dose section above.
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2 g for 1 single dose
First-line fragment. Read the complete Indications and Dose section above.
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2 g for 1 single dose, to be administered
First-line fragment. Read the complete Indications and Dose section above.
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50–60 mg/kg once daily (max.
First-line fragment. Read the complete Indications and Dose section above.
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2 g once daily for 2–3 days
First-line fragment. Read the complete Indications and Dose section above.
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2 g once daily for 2–3 days
First-line fragment. Read the complete Indications and Dose section above.
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50–60 mg/kg once daily (max.
First-line fragment. Read the complete Indications and Dose section above.
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1.5–2 g once daily for 3–6 days
First-line fragment. Read the complete Indications and Dose section above.
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1.5–2 g once daily for 3–6 days
First-line fragment. Read the complete Indications and Dose section above.
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50–75 mg/kg (max. per dose 2 g)
First-line fragment. Read the complete Indications and Dose section above.
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2 g for 1 single dose, dose may be
First-line fragment. Read the complete Indications and Dose section above.
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2 g for 1 single dose
First-line fragment. Read the complete Indications and Dose section above.
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(consult local protocol)
First-line fragment. Read the complete Indications and Dose section above.
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