AMOXICILLIN-WGR
Active ingredient: amoxicillin(as trihydrate)
Consumer Medicine Information
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Published by MIMS January 2025
Consumer medicine information
Amoxicillin-WGR Powder for Suspension
Amoxicillin
BRAND INFORMATION
Brand name
Amoxicillin-WGR Powder for Suspension
Active ingredient
Amoxicillin
Schedule
S4
1 Name of Medicine
Amoxicillin (as amoxicillin trihydrate).
2 Qualitative and Quantitative Composition
Each 5 mL contains 125 mg or 250 mg amoxicillin (as trihydrate).
Excipients with known effect.
Saccharin, sodium, sorbitol.For the full list of excipients, see Section 6.1 List of Excipients.
3 Pharmaceutical Form
Amoxicillin-WGR Powder for Suspension 125 mg/5 mL.
White to off-white powder forming an orange suspension upon reconstitution with water.Amoxicillin-WGR Powder for Suspension 250 mg/5 mL.
White to off-white powder forming an orange suspension upon reconstitution with water.4 Clinical Particulars
4.1 Therapeutic Indications
It is indicated for the treatment of the following infections due to susceptible strains of sensitive organisms.
Note.
Therapy should be guided by bacteriological studies, including sensitivity tests, and by clinical response. However, in emergency cases where the causative organism has not been identified, therapy with amoxicillin may be useful. Clinical judgment will decide whether combination with another antibiotic would provide a sufficiently broad spectrum of activity pending sensitivity test results.Skin and skin structure.
Staphylococcus, non-penicillinase producing; Streptococcus; E. coli (see Section 5.1 Pharmacodynamic Properties, Microbiology).Respiratory (acute and chronic).
H. influenzae; Streptococcus; Strep. pneumoniae; Staphylococcus, non-penicillinase producing; E. coli (see Section 5.1 Pharmacodynamic Properties, Microbiology).Genitourinary tract (complicated and uncomplicated, acute and chronic).
E. coli (see Section 5.1 Pharmacodynamic Properties, Microbiology), P. mirabilis and Strep. faecalis.Gonorrhoea.
N. gonorrhoeae (non-penicillinase producing).Prophylaxis of endocarditis.
Amoxicillin may be used for the prophylaxis of bacterial endocarditis in individuals at particular risk, such as those with a prosthetic heart valve or those who have previously had endocarditis.4.2 Dose and Method of Administration
Amoxicillin-WGR Powder for Suspension is intended for oral administration.
Dosage.
Normal renal function.
Adults and children (over 20 kg).
250 mg every eight hours.Children (under 20 kg).
20 mg/kg/day in equally divided doses every eight hours.In severe infections or those caused by less susceptible organisms, 500 mg every eight hours for adults and 40 mg/kg/day in equally divided doses every eight hours for children may be needed.
Adults.
500 mg every eight hours.Children (under 20 kg).
40 mg/kg/day in equally divided doses every eight hours.Adults.
3 g as a single dose.Cases of gonorrhoea with a suspected lesion of syphilis should have darkfield examinations before receiving amoxicillin and monthly serological tests for a minimum of four months.
Adults.
3 g as a single dose.Use in neonates.
Experience in neonates is too limited to make any recommendations regarding dosage or the appropriateness of the oral route.Use in children.
The children's dosage is intended for individuals whose weight will not cause dosage to be calculated greater than that recommended for adults. Children weighing more than 20 kg should be dosed according to the adult recommendations.Renal impairment.
In renal impairment the excretion of the antibiotic will be delayed, and depending on the degree of impairment, it may be necessary to reduce the total daily dosage.In patients receiving peritoneal dialysis, the maximum recommended dose is 500 mg/day. Amoxicillin may be removed from the circulation by haemodialysis.
Chronic urinary tract infections.
It should be recognised that in the treatment of chronic urinary tract infections, frequent bacteriological and clinical appraisals are necessary. Smaller doses than those recommended above should not be used. In stubborn infections, therapy may be required for several weeks. It may be necessary to continue clinical and/or bacteriological follow-up for several months after cessation of therapy.Duration of treatment.
Treatment should be continued for a minimum of 48 to 72 hours beyond the time that the patient becomes asymptomatic or evidence of bacterial eradication has been obtained. It is recommended that there be at least ten days treatment for any infection caused by haemolytic Streptococci, to prevent the occurrence of acute rheumatic fever or glomerulonephritis.Prophylaxis of endocarditis.
See Table 1.
4.3 Contraindications
Amoxicillin is a penicillin and should not be given to patients with a history of hypersensitivity to β-lactam antibiotics (e.g. penicillins, cephalosporins).
4.4 Special Warnings and Precautions for Use
Serious, and occasionally fatal, hypersensitivity reactions (anaphylaxis, anaphylactoid and severe cutaneous reactions) have been reported in patients receiving β-lactam antibiotics. Hypersensitivity reactions can also progress to Kounis syndrome, a serious allergic reaction that can result in myocardial infarction (see Section 4.8 Adverse Effects (Undesirable Effects)). These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and in atopic individuals. Before commencing therapy with any penicillin careful enquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins or other allergens. If an allergic reaction occurs, appropriate therapy should be instituted and amoxicillin therapy discontinued.
Serious anaphylactic reactions require immediate emergency treatment with adrenaline. Oxygen, intravenous steroids and airway management, including intubation should also be administered as indicated.
Drug induced enterocolitis syndrome (DIES) has been reported mainly in children receiving amoxicillin (see Section 4.8 Adverse Effects (Undesirable Effects)). DIES is an allergic reaction with the leading symptom of protracted vomiting (1-4 hours after administration of amoxicillin) in the absence of allergic skin or respiratory symptoms. Further symptoms could comprise of abdominal pain, diarrhoea, hypotension, or leucocytosis with neutrophilia. There have been severe cases including progression to shock.
Although anaphylaxis is more frequent following parenteral therapy, it has occurred in patients on oral therapy. Before commencing therapy with any penicillin, careful enquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins or other allergens. If an allergic reaction occurs, appropriate therapy should be instituted and amoxicillin therapy discontinued.
Serious anaphylactic reactions require immediate emergency treatment with adrenaline. Oxygen, intravenous steroids and airway management, including intubation, should also be administered as indicated.
Antibiotic associated pseudomembranous colitis has been reported with many antibiotics including amoxicillin. A toxin produced with Clostridium difficile appears to be the primary cause. The severity of the colitis may range from mild to life threatening. Clostridium difficile associated diarrhoea (CDAD) has been reported with the use of nearly all antibacterial agents and may range in severity from mild diarrhoea to fatal colitis. It is important to consider this diagnosis in patients who develop diarrhoea or colitis in association with antibiotic use (this may occur up to several weeks after cessation of antibiotic therapy). If prolonged or significant diarrhoea occurs or the patient experiences abdominal cramps, treatment should be discontinued immediately and the patient investigated further. Mild cases usually respond to drug discontinuation alone. However, in moderate to severe cases appropriate therapy with a suitable oral antibiotic agent effective against Clostridium difficile should be considered. Fluids, electrolytes and protein replacement should be provided when indicated. Drugs which delay peristalsis, e.g. opiates and diphenoxylate with atropine (Lomotil) may prolong and/or worsen the condition and should not be used.
Adequate fluid intake and urinary output must be maintained in patients receiving high doses of amoxicillin.
Abnormal prolongation of prothrombin time (increased INR) has been reported rarely in patients receiving amoxicillin and oral anticoagulants. Appropriate monitoring should be undertaken when anticoagulants are prescribed concurrently. Adjustments in the dose of oral anticoagulants may be necessary to maintain the desired level of anticoagulation.
Amoxicillin should be avoided if infectious mononucleosis is suspected since the occurrence of a morbilliform rash has been associated with this condition following the use of amoxicillin.
Prolonged use may occasionally result in overgrowth of non-susceptible organisms.
As with any potent drug, periodic assessment of renal, hepatic and haematopoietic function should be made during prolonged therapy. The possibility of superinfections with mycotic or bacterial pathogens should be kept in mind during therapy. If superinfections occur (usually involving Aerobacter, Pseudomonas or Candida), the drug should be discontinued and/or appropriate therapy instituted.
Amoxicillin, an aminopenicillin, is not the treatment of choice in patients presenting with sore throat or pharyngitis because of the possibility that the underlying cause is infectious mononucleosis, in the presence of which there is a high incidence of rash if amoxicillin is used.
Amoxicillin should be given with caution to patients with lymphatic leukaemia, since they are especially susceptible to ampicillin induced skin rashes.
Following single dose therapy of acute lower urinary tract infections, the urine should be cultured. A positive culture may be evidence of a complicated or upper urinary tract infection and call for a longer or larger course of therapy.
Adequate fluid intake and urinary output must be maintained in patients receiving high doses of amoxicillin.
Use in renal impairment.
Dosage should be adjusted in patients with renal impairment (see Section 4.2 Dose and Method of Administration).In patients with reduced urine output, crystalluria (including acute renal injury) has been observed very rarely, predominantly with parenteral therapy. During the administration of high doses of amoxicillin, it is advisable to maintain adequate fluid intake and urinary output in order to reduce the possibility of amoxicillin crystalluria. In patients with bladder catheters, a regular check of patency should be maintained (see Section 4.8 Adverse Effects (Undesirable Effects); Section 4.9 Overdose).
Use in the elderly.
No data available.Paediatric use.
No data available.Effects on laboratory tests.
Oral administration of amoxicillin will result in high urine concentrations of amoxicillin. Since high urine concentrations of amoxicillin may result in false positive reactions when testing for the presence of glucose in urine using Clinitest, Benedict's solution or Fehling's solution, it is recommended that glucose tests based on enzymatic glucose oxidase reactions (such as Clinistix or Tes-Tape) be used.Following administration of ampicillin to pregnant women a transient decrease in plasma concentration of total conjugated oestriol, oestriol-glucuronide, conjugated oestrone and oestradiol has been noted. This effect may also occur with amoxicillin.
4.5 Interactions with Other Medicines and Other Forms of Interactions
Probenecid decreases the renal tubular secretion of amoxicillin. Concurrent use with amoxicillin may result in increased and prolonged blood levels of amoxicillin.
The concurrent administration of allopurinol and ampicillin increases substantially the incidence of rashes in patients receiving both drugs as compared to patients receiving ampicillin alone. It is not known whether this potentiation of ampicillin rashes is due to allopurinol or the hyperuricaemia present in these patients. Similar reactions can be expected with amoxicillin.
In common with other antibiotics, amoxicillin may affect the gut flora, leading to lower oestrogen re-absorption and reduced efficacy of combined oral contraceptives.
In the literature there are rare cases of increased international normalised ratio in patients maintained on acenocoumarol or warfarin and prescribed a course of amoxicillin. If coadministration is necessary, the prothrombin time or international normalised ratio should be carefully monitored with the addition or withdrawal of amoxicillin.
Tetracyclines and other bacteriostatic drugs may interfere with the bactericidal effects of amoxicillin.
Methotrexate.
Penicillins may reduce the excretion of methotrexate causing a potential increase in toxicity.Concomitant use of probenecid is not recommended. Probenecid decreases the renal tubular secretion of amoxicillin. Concomitant use of probenecid may result in increased and prolonged blood levels of amoxicillin.
4.6 Fertility, Pregnancy and Lactation
Effects on fertility.
No data available.Animal studies with amoxicillin have shown no teratogenic effects. Amoxicillin has been in extensive clinical use since 1972 and its suitability in human pregnancy has been well documented in clinical studies.
Amoxicillin may be used in pregnancy when the potential benefits outweigh the potential risks associated with treatment.
Use in labour and delivery.
Oral ampicillin class antibiotics are generally poorly absorbed during labour. Studies in guinea pigs have shown that intravenous administration of ampicillin decreased the uterine tone, frequency of contractions, height of contractions and duration of contractions. However, it is not known whether the use of amoxicillin in humans during labour or delivery has immediate or delayed adverse effects on the foetus, prolongs the duration of labour or increases the likelihood that forceps delivery or other obstetrical intervention or resuscitation of the newborn infant will be necessary.4.7 Effects on Ability to Drive and Use Machines
The effects of this medicine on a person's ability to drive and use machines were not assessed as part of its registration.
4.8 Adverse Effects (Undesirable Effects)
As with other penicillins, it may be expected that untoward reactions will be essentially limited to sensitivity phenomena. They are more likely to occur in individuals who have previously demonstrated hypersensitivity to penicillins.
The following adverse reactions have been reported as associated with the use of amoxicillin.
Cardiac disorders.
Kounis syndrome: not known.Infections and infestations.
Mucocutaneous candidiasis has been reported very rarely.Gastrointestinal.
Nausea, vomiting, diarrhoea. Intestinal candidiasis and antibiotic associated colitis, including pseudomembranous colitis and haemorrhagic colitis have been reported rarely. Black hairy tongue has been reported very rarely. Drug induced enterocolitis syndrome: not known (see Section 4.4 Special Warnings and Precautions for Use).Skin and subcutaneous tissue disorders.
Linear IgA disease: not known.Hypersensitivity reactions.
Erythematous maculopapular rash, pruritus and urticaria have been reported occasionally. Rarely, skin reactions such as erythema multiforme and Stevens-Johnson syndrome, toxic epidermal necrolysis and bullous, exfoliative dermatitis and acute generalized exanthematous pustulosis (AGEP) and drug reaction with eosinophilia and systemic symptoms (DRESS) and symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) (baboon syndrome) have been reported. As with other antibiotics, severe allergic reactions including angioneurotic oedema, anaphylaxis, serum sickness, hypersensitivity vasculitis and interstitial nephritis have been reported rarely.Whenever such reactions occur, amoxicillin should be discontinued.
Note.
Urticaria, other skin rashes and serum sickness-like reactions may be controlled with antihistamines and, if necessary, systemic corticosteroids. Anaphylaxis is the most serious reaction experienced (see Section 4.4 Special Warnings and Precautions for Use).Hepatic.
A moderate rise in AST and/or ALT has been noted occasionally but the significance of this finding is unknown. As with other β-lactam antibiotics, hepatitis and cholestatic jaundice have been reported rarely.Haemic and lymphatic systems.
Reactions such as anaemia, thrombocytopenia, thrombocytopenic purpura, eosinophilia and leucopenia (including severe neutropenia or agranulocytosis) have been reported during therapy with other penicillins. These reactions are usually reversible on discontinuation of therapy and are believed to be hypersensitivity phenomena. Prolongation of bleeding time and prothrombin time have also been reported rarely.Renal and urinary tract disorders.
Interstitial nephritis, crystalluria including renal injury: not known (see Section 4.9 Overdose).CNS effects.
CNS effects have been seen rarely. These include aseptic meningitis, hyperkinesia, dizziness and convulsions. Convulsions may occur in patients with impaired renal function or in those receiving high doses.Miscellaneous.
Superficial tooth discolouration has been reported very rarely in children. Good oral hygiene may help to prevent tooth discolouration as it can usually be removed by brushing.Reporting suspected adverse effects.
Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at http://www.tga.gov.au/reporting-problems.4.9 Overdose
Symptoms.
Gastrointestinal effects such as nausea, vomiting and diarrhoea may be evident.Treatment.
Symptoms of water/electrolyte imbalance should be treated symptomatically. During the administration of high doses of amoxicillin, adequate fluid intake and urinary output must be maintained to minimise the possibility of amoxicillin crystalluria. Amoxicillin crystalluria, in some cases leading to renal failure, has been observed (see Section 4.4 Special Warnings and Precautions for Use).Amoxicillin can be removed from the circulation by haemodialysis.
For information on the management of overdose, contact the Poisons Information Centre on 131126 (Australia).
5 Pharmacological Properties
5.1 Pharmacodynamic Properties
Mechanism of action.
It is active in vitro against most strains of Haemophilus influenzae*, Neisseria gonorrhoeae*, N. meningitidis, Escherichia coli*, Proteus mirabilis* and Salmonellae. Because amoxicillin does not resist destruction by penicillinase, it is not active against penicillinase-producing organisms, particularly penicillinase-producing staphylococci. All strains of Pseudomonas species, Klebsiella species, Enterobacter species, indole positive Proteus species, Serratia marcescens, Citrobacter species, penicillinase-producing N. gonorrhoeae and penicillinase-producing H. influenzae are resistant. In vitro studies have demonstrated the susceptibility of most strains of the following Gram-positive bacteria: α- and β-haemolytic streptococci, Diplococcus pneumoniae, non-penicillinase producing staphylococci and Streptococcus faecalis. These organisms are susceptible to amoxicillin at serum concentrations which may be expected following the recommended doses. However, some of the organisms were susceptible to amoxicillin only at concentrations achieved in the urine (see Section 4.1 Therapeutic Indications).
*Activity refers only to β-lactamase negative strains.
Escherichia coli isolates are becoming increasingly resistant to amoxicillin in vitro due to the presence of penicillinase producing strains.
Strains of gonococci that are relatively resistant to benzylpenicillin may be sensitive to amoxicillin.
The following in vitro data are available, but their clinical significance is unknown. See Table 2.
A positive β-lactamase test predicts resistance to penicillin, ampicillin and amoxicillin. See Table 3.
Note.
Because amoxicillin has a greater in vitro activity against S. pneumoniae than does ampicillin, the majority of S. pneumoniae strains with intermediate susceptibility to ampicillin are fully susceptible to amoxicillin.A report of "Susceptible" indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of "Intermediate" indicates that the result should be considered equivocal, and if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone, which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of "Resistant" indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected.
Note.
The prevalence of resistance may vary geographically for selected species and local information on resistance is desirable, particularly when treating severe infections. This information gives only an approximate guidance on probabilities whether organisms will be susceptible to amoxicillin.Susceptibility to amoxicillin will vary with geography and time and local susceptibility data should be consulted where available and microbiological sampling and susceptibility testing performed where necessary.
Cross-resistance.
Other β-lactams, β-lactam/β-lactamase inhibitor combinations and cephalosporins.Resistance mechanisms.
Production of penicillinase, altered penicillin binding proteins.Clinical trials.
No data available.5.2 Pharmacokinetic Properties
Absorption.
Amoxicillin is stable in the presence of gastric acid and is rapidly and well absorbed after oral administration, even in the presence of food.Orally administered doses of 250 and 500 milligrams result in average peak serum levels one to two hours after administration of 5 microgram/mL and 6.6 to 10.8 microgram/mL respectively. Detectable serum levels of amoxicillin are present 8 hours after ingestion of a single dose.
Distribution.
Amoxicillin is not highly protein bound, being only 17% protein bound in serum as measured by ultrafiltration or equilibrium dialysis.Amoxicillin diffuses rapidly into most body tissues and fluids, with the exception of brain and spinal fluid except when the meninges are inflamed. Amoxicillin has been shown to diffuse into sputum and saliva and is excreted mainly via the urine where it exists in a high concentration.
The amount to be found in the bile is variable depending on normal biliary secretory function.
Excretion.
The half-life of amoxicillin is 61.3 minutes with normal renal function, and in the absence of renal function is 16 to 20 hours.Amoxicillin is excreted in the urine both unchanged and as penicilloic acid. About 75% of a 1 g dose is excreted in the urine in six hours in the presence of normal renal function (60% is biologically active and 15% is penicilloic acid). However about 32% of a 3 g dose is excreted via the urine as the biologically active component in 8 hours (by which time most of the urinary excretion is complete). This proportional difference in the amount excreted from the different doses reflects a lack of linearity between doses and extent of absorption with a levelling off at higher doses of oral amoxicillin.
Excretion of amoxicillin can be delayed by concurrent administration of probenecid, thus prolonging its therapeutic effect.
5.3 Preclinical Safety Data
Genotoxicity.
No data available.Carcinogenicity.
No data available.6 Pharmaceutical Particulars
6.1 List of Excipients
Saccharin sodium, colloidal silica anhydrous, sodium citrate dihydrate, sorbitol, sunset yellow FCF, xanthan gum, tutti frutti flavor (PI 183).
6.2 Incompatibilities
Incompatibilities were either not assessed or not identified as part of the registration of this medicine.
6.3 Shelf Life
In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.
Unused suspension must be discarded after 14 days.
6.4 Special Precautions for Storage
Store the powder below 25°C. Protect from moisture.
After reconstitution with water, stored at 2-8°C in a refrigerator. Do not freeze.
6.5 Nature and Contents of Container
Amoxicillin-WGR Powder for Suspension 125 mg/5 mL.
100 mL when reconstituted.Bottle: AUST R Number 432351.
Amoxicillin-WGR Powder for Suspension 250 mg/5 mL.
100 mL when reconstituted.Bottle: AUST R Number 432352.
Not all strengths may be available.
6.6 Special Precautions for Disposal
In Australia, any unused medicine or waste material should be disposed of by taking to your local pharmacy.
6.7 Physicochemical Properties
Amoxicillin trihydrate is a white or almost white, crystalline powder, slightly soluble in water and in alcohol.
Amoxicillin trihydrate is a semisynthetic antibiotic and is a member of the penicillinase-stable group of penicillins derived from the penicillin nucleus, 6-aminopenicillanic acid, isolated at Beecham Research Laboratories.
Chemical structure.
Chemical name: (2S,5R,6R)-6-[[(2R)-2- amino-2-(4-hydroxyphenyl) acetyl]amino]-3,3dimethyl- 7-oxo-4-thia-1-azabicyclo[3.2.0] heptane-2-carboxylic acid trihydrate.Molecular formula: C16H19N3O5S.3H2O.
Molecular weight: 419.4.
CAS number.
61336-70-7.7 Medicine Schedule (Poisons Standard)
S4 - Prescription Only Medicine.
Summary Table of Changes
