INFORMATION FOR HEALTH PROFESSIONALS
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PENAMOX Capsules:
250mg: Red cap with a white body printed Penamox 250mg, size 2 capsule, 0.6 x 1.7cm.
500mg: Red cap with a white body printed Penamox 500mg, size 0 capsules, 0.7 x 2.2cm.
PENAMOX Syrup:
Fruit flavoured syrups providing 125mg or 250mg amoxycillin per 5mL. Presented as a white powder in bottles for preparing 100mL. The formulations contain no sugar. Prepared solutions of all strengths and formulations are white to cream in colour.
PENAMOX differs in-vitro from benzylpenicillin in the gram-negative spectrum. PENAMOX has the same gram-positive and gram-negative spectrum as ampicillin.
In-vitro, most strains of Haemophilus influenzae, Neisseria gonorrhoea, Neisseria meningitidis, Escherichia coli, Proteus mirabilis and Salmonellae are sensitive to PENAMOX at serum concentrations which may be expected following the recommended doses. Strains of gonococci which are relatively resistant to benzylpenicillin may be sensitive to PENAMOX.
In-vitro studies have also demonstrated the sensitivity of most strains of the following gram-positive bacteria: alpha- and beta-haemolytic streptococci, Streptococcus pneumoniae, non-penicillinase-producing staphylococci and Streptococcus faecalis. However, some of the organisms were sensitive to PENAMOX only at concentrations achieved in the urine.
PENAMOX is not effective against penicillinase-producing bacteria, particularly resistant staphylococci.
All strains of Pseudomonas and most strains of Klebsiella and Aerobacter are resistant.
Like benzylpenicillin, PENAMOX is bactericidal against sensitive organisms during the stage of active multiplication.
It is believed to act through the inhibition of biosynthesis of cell wall mucopeptide.
PENAMOX is stable in the presence of gastric acid and is rapidly and well absorbed after oral administration, even in the presence of food. Peak concentrations of 6-7mcg/mL occur at 1.5-2 hours after a single dose of 500mcg as the capsule. Serum levels of amoxycillin have been measurable for up to 10h after administration of the 500mg capsule.
PENAMOX has been shown to diffuse in 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. The half-life of PENAMOX is approximately 1.3h in subjects with normal renal function and 7-10h in patients with renal failure off dialysis. The half-life may be extended to neo-nates. In persons over 60 the half-life can be up to twice as long.
PENAMOX is excreted in the urine both unchanged and as penicilloic acid. About 75% of a 1g dose is excreted in the urine in 6 hours in the presence of normal renal function (60% is biologically active and 15% is penicilloic acid).
However about 32% of a 3g 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 absorption with a levelling off at higher doses of oral amoxycillin.
Excretion of PENAMOX can be delayed by concurrent administration of probenecid, thus prolonging its therapeutic effect.
PENAMOX is not highly protein-bound, being only 17% protein-bound in serum as compared to 59% for penicillin G.
About 60-70% of an oral dose of PENAMOX is excreted in the urine.
Treatment of Infection: PENAMOX is indicated in the treatment of infections due to susceptible strains of the following organisms.
| Gram-negative organisms: | Gram-positive organisms: |
|---|---|
| Haemophilus influenzae | Streptococcus species |
| Escherichia coli | Streptococcus pneumoniae |
| Proteus mirabilis | Non-penicillinase-producing staphylococci |
| Neisseria gonorrhoea |
PENAMOX may be useful in instituting therapy prior to
bacteriology; however, bacteriological studies to determine the causative
organisms and their sensitivity to PENAMOX should be performed.
Prophylaxis of Endocarditis: PENAMOX may be used for the prevention of bacteraemia, associated with procedures such as dental extraction, in patients at risk of developing bacterial endocarditis.
Upper Respiratory Tract Infections: (Due to streptococci, pneumococci, non-penicillinase-producing staphylococci and H. influenzae)
Genito-Urinary Tract Infections: (Due to Escherichia coli, Proteus mirabilis and Strep. faecalis)
Skin and Soft Tissue Infections: (Due to Streptococci, sensitive Staphylococci and Escherichia coli)
In severe infections or those caused by less susceptible organisms, 500mg every 8 hours for adults and 50mg/kg/day in equally divided doses every 8 hours for children may be needed.
Lower Respiratory Tract Infections: (Due to Streptococci, Pneumococci, non-penicillinase-producing Staphylococci and Haemophilus influenzae).
High Dose Therapy: An adult dosage of 3g twice daily is recommended in appropriate cases for the treatment of severe or recurrent purulent infection of the respiratory tract. (Maximum recommended oral dosage 6g daily in divided doses.)
Prophylaxis of Endocarditis - Dental Procedures: Prophylaxis for patients undergoing extraction, scaling or surgery involving gingival tissues who have not received a penicillin in the previous month, are not having a general anaesthetic and do not have a prosthetic heart valve.
Patients for whom referral to hospital is recommended: patients to be given a general anaesthetic who have been given a penicillin in the previous month, patients to be given a general anaesthetic who have a prosthetic heart valve or patients who have had one or more attacks of endocarditis. The following schedule is recommended for these patients:
Appropriate parenteral therapy is:
Consult the appropriate data sheet for full prescribing information if parenteral amoxycillin or gentamicin therapy is being used. Amoxycillin ( IBIAMOX ) and gentamicin should not be mixed in the same syringe.
Patients having general anaesthsia, oral antibiotics considered to be appropriate:
Patients having a general anaesthetic for whom oral antibiotics are considered inappropriate.
Urethritis (due to Neisseria gonorrhoea):
Adults: 3g as single dose. Cases of gonorrhea with a suspected lesion of syphilis should have dark field examinations before receiving PENAMOX and monthly serological tests for a minimum of four months. Probenecid 1g is also recommended concurrently with PENAMOX.
Acute, Uncomplicated Lower Urinary Tract Infections: (due to Escherichia coli, Proteus mirabilis, Strep. faecalis, non-penicillinase producing staphylococci)
Note: The children's dose is intended for individuals whose weight will not cause a calculated dose greater than that recommended for adults.
Children weighing more than 20kg should be dosed according to the adult recommendations.
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.
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.
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 10 days treatment for any infection caused by haemolytic streptococci to prevent the occurrence of rheumatic fever or glomerulo-nephritis.
The use of this medicine is contraindicated in individuals with a history of allergic reaction to the penicillins.
Serious and occasionally fatal hypersensitivity (anaphylactoid) reactions have been reported in patients on penicillin therapy.
Although anaphylaxis is more frequent following parenteral therapy, it has occurred in patients on oral penicillins. 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 PENAMOX therapy discontinued.
Serious anaphylactoid reactions require emergency treatment with adrenalin, oxygen and intravenous steroids. Airway management including intubation should also be administered as indicated.
As with any potent medicine, 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), PENAMOX should be discontinued and/or appropriate therapy instituted. Pseudomembranous colitis and acute haemorrhagic colitis can occur with PENAMOX therapy.
PENAMOX should be given with caution to patients with infectious mononucleosis or lymphatic leukemia since they are especially susceptible to ampicillin induced skin rashes.
Use in Pregnancy and Lactation: Safety for use in pregnancy has not been established. Penicillins are excreted in breast milk. Although significant problems in humans have not been documented, the use of penicillins by nursing mothers may lead to sensitization, diarrhoea, cardidiasis and skin rash in the infant.
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 incidence of adverse effects is rare. The following adverse reactions have been reported as associated with the use of PENAMOX.
Gastrointestinal: Nausea, vomiting, diarrhoea, abdominal pain, cramps or tenderness, pseudomembranous colitis.
Hypersensitivity Reactions: Erythematous maculopapular rashes and urticaria or wheezing. Whenever such reactions occur, PENAMOX should be discontinued. (Note: urticaria, other skin rashes and serum sickness-like reactions may be controlled with antihistamines and, if necessary, systemic corticosteroids).
Liver: Moderate rise in SGOT has been noted, but the significance of this finding is unknown.
Haemic and Lymphatic Systems: Such reactions as anaemia, neutropenia, thrombocytopenia, thrombocytopenic purpura, eosinophilia, leucopenia and 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.
Administration of probenecid in conjunction with PENAMOX results in sustained serum levels of amoxycillin which may be made use of in certain dosage regimens.
There is an increased incidence of skin rash when ampicillin is administered with allopurinol and a similar reaction should be considered if amoxycillin is required by any patient currently taking allopurinol.
Similar to ampicillin, concurrent administration of oral contraceptives with IBIAMOX may reduce efficacy of the former. Should this antibiotic be used, an alternative contraception method is advisable.
No incidence of overdosage has been reported.
Prior to use, oral presentations of PENAMOX should be stored in a dry place. Once dispensed, PENAMOX syrups should be used within the periods stated on the labels. Any remaining syrup should be discarded.
Prescription Medicine.
PENAMOX Capsules: 250mg packs of 30 and 100
500mg packs of 30 and 100
PENAMOX Syrup: 125mg and 250mg per 5mL
100mL bottles
PENAMOX is amoxycillin trihydrate, the formula of which is C16H19N3O5S,3H2O. The molecular weight is 419.4.
1.15g of amoxycillin trihydrate is equivalent to approximately 1g of amoxycillin.
Douglas Pharmaceuticals Ltd
PO Box 45-027
Auckland 8
Ph: (09) 835-0660
Fax: (09) 835-0665
23 July 1999