INDICATIONS     CONTRA-INDICATIONS     DOSAGE     SIDE-EFFECTS     PREGNANCY     OVERDOSE     IDENTIFICATION     PATIENT INFORMATION

Logo PURBAC® ADULT TABLETS
PURBAC® DOUBLE STRENGTH TABLETS
PURBAC® PAEDIATRIC SUSPENSION

SCHEDULING STATUS:
S4

PROPRIETARY NAME:
(and dosage form)

PURBAC® ADULT TABLETS
PURBAC
® DOUBLE STRENGTH TABLETS
PURBAC
® PAEDIATRIC SUSPENSION

COMPOSITION:
1. Each PURBAC
® ADULT tablet contains:
Trimethoprim         80 mg
Sulphamethoxazole         400 mg
Preserved with Nipastat         0,025% m/m
2. Each PURBAC® D.S. tablet contains:
Trimethoprim         160 mg
Sulphamethoxazole         800 mg
Preserved with Nipastat         0,025% m/m
3. Each 5 mL of the PURBAC® PAEDIATRIC suspension contains:
Trimethoprim         40 mg
Sulphamethoxazole         200 mg
Alcohol         1,44% v/v
Preserved with Nipastat         0,3% m/v

PHARMACOLOGICAL CLASSIFICATION:
A 20.2 Antimicrobial (Chemotherapeutic) Agents. (Other than antibiotics).

PHARMACOLOGICAL ACTION:
Co-trimoxazole exerts its bactericidal action by the sequential blockade of two enzymes intervening in the biosynthesis of folinic acid in the micro-organism. Co-trimoxazole is bactericidal at concentrations at which the active ingredients trimethoprim and sulphamethoxazole, are usually bacteriostatic. It is therefore often active against organisms resistant to one of the active ingredients thereby minimising the risk of bacterial resistance.

INDICATIONS:
Co-trimoxazole is effective against a wide range of Gram-positive and Gram-negative organisms.
It is indicated for:
1. upper and lower respiratory tract infections e.g. acute and chronic bronchitis, bronchiectasis, tonsillitis, sinusitis and pharyngitis, otitis media, pneumonia and pneumocystis corinii pneumonitis (see Precautions).
2. renal and urinary tract infections e.g. pyelitis, pyelonephritis, urethritis, acute and chronic cystitis and cystopyelitis, including prostatitis.
3. gastro-intestinal tract infections e.g. enteritis, typhoid and paratyphoid fever, typhoid carriage, bacillary dysentery and cholera (as an adjunct to fluid and electrolyte replacement).
4. genital tract infections - both male and female including gonococcal infections.
5. skin infections e.g. pyoderma, boils, furuncles, abscesses.
6. other bacterial infections - acute brucellosis, mycetoma except those caused by true fungi, nocardiosis, acute and chronic osteomyelitis.

CONTRA-INDICATIONS:
Co-trimoxazole is contra-indicated in patients suffering from porphyria, liver parenchymal damage, megaloblastic anaemia due to folic acid deficiency, severe renal insufficiency, and a history of hypersensitivity to sulphonamides or trimethoprim. Co-trimoxazole should not be administered during pregnancy, to women prior to delivery, or to nursing mothers. It should also not be used in premature or newborn infants during the first few weeks of life.

WARNING:
A high incidence of side-effects occurs in immunocompromised patients, such as those suffering from Aids or patients receiving immunosuppressive therapy. The adverse effects include skin rash, recurrent fever, neutropenia, thrombocytopenia and raised liver enzyme values.
Co-trimoxazole may cause the occurrence of erythema multiforme, toxic dermal necrolysis and allergic vasculitis.
Treatment should be discontinued immediately when a rash appears because of the danger of severe allergic reactions.

DOSAGE AND DIRECTIONS FOR USE:
Children 6-12 years:
One Purbac Adult tablet every 12 hours after meals.
Adults and Children over 12 Years:
The usual dose is two Purbac Adult Tablets or one Purbac D.S. tablet every 12 hours after meals. The maximum dose (for particularly severe cases) is three Purbac Adult tablets or one and a half Purbac D.S. tablets every 12 hours. The minimum dosage for long-term treatment (longer than 14 days) is one Purbac Adult or a half Purbac D.S. tablet every 12 hours.
Paediatric Dosage
Suspension:
The following dosage structure is recommended: 6 mg trimethoprim plus 30 mg sulphamethoxazole per kg body mass daily which approximately corresponds to the following dosage according to age:
Children 6 - 12 years: Two medicine measures (10 mL) twice daily.
(BOTTLE TO BE SHAKEN BEFORE USE)
In the treatment of acute infections, co-trimoxazole should be administered for at least 5 days or for at least 2 days after the symptoms have disappeared. If clinical improvement is not evident after 7 days therapy, the patient should be reassessed.
Dosage recommendation in renal impairment: If Purbac is indicated for patients with renal impairment, the following dosage scheme, based on creatinine clearance is suggested:
Creatinine clearance:
Above 25 mL/min standard dosage.
15-25 mL/min        standard dosage for a maximum of 3 days followed by half the standard daily dose.
Below 15 mL/min        not to be administered unless haemodialysis facilities are available when half the standard daily dose may be given.
Measurements of plasma concentrations of sulphamethoxazole at intervals of 2 days are recommended in samples obtained 12 hours after administration of Purbac. If the concentration of total sulphamethoxazole exceeds 150 micrograms/mL then treatment should be interrupted until the value falls below 120 micrograms/mL.
No information is available for children with renal failure.

SIDE-EFFECTS AND SPECIAL PRECAUTIONS:
Hypersensitivity reactions particularly involving the skin are among the most common adverse effects of co-trimoxazole and are usually due to the sulphamethoxazole component. The Stevens-Johnson and Lyell’s syndromes have been reported.
Adverse effects on the gastro-intestinal tract may also occur fairly frequently.
Sulphamethoxazole:
Sulphamethoxazole may cause nausea, vomiting and diarrhoea.
Hypersensitivity reactions may occur. Those involving the skin include rashes, photosensitivity reactions, exfoliative dermatitis, toxic epidermal necrolysis (Lyell’s syndrome), and erythema nodosum. A severe, potentially fatal form of erythema multiforme, associated with widespread lesions of the skin and mucous membranes, termed the Stevens-Johnson syndrome, may occur.
Systemic lupus erythematosus, particularly exacerbations of pre-existing disease, has also been reported.
Nephrotoxic reactions, which may result in renal failure, have been attributed to hypersensitivity to sulphamethoxazole.
Lumbar pain, haematuria, oliguria, and anuria may occur due to crystallisation in the urine of sulphamethoxazole or its less soluble acetylated metabolite.
Blood disorders, mostly as a result of hypersensitivity reactions, may occur and include agranulocytosis, aplastic anaemia, thrombocytopenia, leucopenia, hypoprothrombinaemia, and eosinophilia. Acute haemolytic anaemia often associated with glucose-6-phosphate dehydrogenase deficiency may occur.
Other side-effects which may be manifestations of a generalised hypersensitivity reaction to sulphamethoxazole include a syndrome resembling serum sickness, hepatotoxic reactions, myocarditis, pancreatitis, pulmonary eosinophilia, and vasculitis including polyarteritis nodosa.
Anaphylaxis has been reported.
Sulphamethoxazole may cause cyanosis due to methaemoglobinaemia or sulphaemoglobinaemia.
Other side-effects include effects on the eyes such as optic neuropathy or transient myopia, fever, hypothyroidism, and neurological reactions including ataxia, dizziness, fatigue, headache, insomnia, peripheral neuritis, and vertigo.
Sulphamethoxazole may cause alterations of the bacterial flora in the gastro-intestinal tract. There is, therefore, the possibility that pseudomembranous colitis may occur.
Slow acetylators of sulphamethoxazole may be at greater risk of adverse reactions than fast acetylators.
Trimethoprim:
Side-effects caused by trimethoprim include pruritus, skin rash, fever, nausea, vomiting, and sore mouth.
Precautions:
Purbac should be given with caution to patients with actual or possible folate deficiency because of possible interference with human folate metabolism by trimethoprim, and administration of folinic acid could be considered. Purbac should also be used with caution in patients receiving pyrimethamine as they may develop megaloblastic anaemia due to the trimethoprim component.
Adverse effects on the blood may be more severe in malnourished or elderly patients; there also appears to be an increased risk of thrombocytopenia in elderly patients concurrently receiving diuretics, mainly thiazides. All patients receiving prolonged treatment with Purbac should be given regular blood examinations.
Purbac should be used cautiously and in reduced dosage in patients with impaired renal function. Because of the risk of crystalluria, an adequate fluid intake should be maintained and the administration of alkalis may be necessary if very large doses are used.
Interactions:
Cross-sensitivity has been observed between sulphamethoxazole and chemically related compounds such as some diuretics, particularly acetazolamide and thiazides, and the sulphonylurea hypoglycaemic agents. Sulphamethoxazole may potentiate the effects of some medicines, such as oral anticoagulants, methotrexate, and phenytoin; this may be due to displacement of the compound from plasma protein binding sites or to inhibition of metabolism.
High doses of sulphamethoxazole may have a hypoglycaemic effect; the antidiabetic effect of the sulphonylurea compounds may be enhanced by the concomitant administration of sulphamethoxazole. The action of sulphamethoxazole may be antagonised by para-aminobenzoic acid and compounds derived from it, particularly the procaine group of local anaesthetics.
Paraldehyde has been reported to increase the acetylation of sulphamethoxazole with subsequent increased risk of crystalluria.
Sulphamethoxazole may interfere with some diagnostic tests including those for urea, creatinine, and urinary glucose and urobilinogen.
Trimethoprim may potentiate the anticoagulant effect of warfarin. It also prolongs the half-life of phenytoin.
Trimethoprim has been reported to interact with a number of other medicines by interfering with their clearance; such medicines include digoxin, procainamide, and tolbutamide.
Reversible deterioration in renal function has been reported in patients given trimethoprim and cyclosporin following renal transplantation.
Trimethoprim may interfere with some diagnostic tests including serum methotrexate assay where dihydrofolate reductase is used, and the Jaffe reaction for creatinine.

KNOWN SYMPTOMS OF OVERDOSAGE AND PARTICULARS OF ITS TREATMENT:
Possible symptoms of overdosage are those enumerated under side-effects. Treatment is symptomatic and supportive.

IDENTIFICATION:
PURBAC
® ADULT Tablets
White, flat bevelled edged tablets, engraved “PURBAC" on the one side, and having the Lennon logo (mortar and pestle) on the other.
PURBAC
® D.S. Tablets
White, oblong, biconvex, bisected tablets engraved “PURBAC DS”on the one side and having the Lennon Logo (mortar and pestle) on the other.
PURBAC
® PAEDIATRIC Suspension
A smooth, pink suspension with a characteristic aniseed odour.

PRESENTATION:
PURBAC®ADULT Tablets Blister packs of 20 tablets
  Securitainers of 100 tablets
  PVC Xactics bottles of 1000 tablets
PURBAC®D.S. Tablets Blister packs of 10 tablets
  PVC Xactics bottles of 250 tablets.
PURBAC®PAEDIATRIC Suspension Bottles of 50 mL, 100 mL and 500 mL.

STORAGE INSTRUCTIONS:
Store below 25°C
Protect from light and moisture
KEEP OUT OF REACH OF CHILDREN.

REGISTRATION NUMBERS:
PURBAC® ADULT Tablets:         J/20.2/339.
PURBAC® D.S. Tablets:         L/20.2/295.
PURBAC® PAEDIATRIC Suspension:         K/20.2/241.

NAME AND BUSINESS ADDRESS OF APPLICANT:
Pharmacare Limited
7 Fairclough Road
PORT ELIZABETH
6001

DATE OF PUBLICATION OF THIS PACKAGE INSERT:
21/10/76
                D128
                A&S PRINTERS

Updated on this site: May 2003
Current: September 2004
Source: Community Pharmacy

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