If you have been prescribed PURBAC, you are taking a medicine used to treat certain bacterial infections. It comes in three forms: PURBAC ADULT tablets, PURBAC DOUBLE STRENGTH tablets, and PURBAC PAEDIATRIC SUSPENSION. The active ingredients are trimethoprim and sulphamethoxazole, which work together to fight bacteria.
In simple terms, this medicine is used for a range of infections, including some infections of the lungs, ears, throat, kidneys, bladder, stomach, skin and genital tract. It may also be used for certain other bacterial infections named in the source. This is a Schedule 4 medicine in South Africa, which means it should be used only under proper medical supervision.
Quick facts: PURBAC is an antimicrobial medicine that contains two ingredients. You usually take it every 12 hours after meals if you are an adult or older child, but the exact dose depends on age, product form, and sometimes kidney function. It is important to complete the course exactly as prescribed and to stop using it and get medical advice if you develop a rash.
What it is and what it is used for
Active ingredients and medicine type
PURBAC contains two active ingredients:
- Trimethoprim
- Sulphamethoxazole
These two medicines are combined in one product. PURBAC is listed as an antimicrobial (chemotherapeutic) agent. The strengths differ depending on the product:
- PURBAC ADULT tablet: 80 mg trimethoprim + 400 mg sulphamethoxazole per tablet
- PURBAC DOUBLE STRENGTH tablet: 160 mg trimethoprim + 800 mg sulphamethoxazole per tablet
- PURBAC PAEDIATRIC SUSPENSION: 40 mg trimethoprim + 200 mg sulphamethoxazole in each 5 ml
What it is used for
PURBAC is indicated for a wide range of bacterial infections. According to the source, it may be used for:
- Upper and lower respiratory tract infections, such as:
- acute and chronic bronchitis
- bronchiectasis
- tonsillitis
- sinusitis
- pharyngitis
- otitis media
- pneumonia
- Pneumocystis carinii pneumonitis
- Kidney and urinary tract infections, such as:
- pyelitis
- pyelonephritis
- urethritis
- acute and chronic cystitis
- cystopyelitis
- prostatitis
- Gastrointestinal infections, such as:
- enteritis
- typhoid fever
- paratyphoid fever
- typhoid carriage
- bacillary dysentery
- cholera (used together with fluid and electrolyte replacement)
- Genital tract infections in males and females, including gonococcal infections
- Skin infections, such as:
- pyoderma
- boils
- furuncles
- abscesses
- Other bacterial infections, including:
- acute brucellosis
- mycetoma except those caused by true fungi
- nocardiosis
- acute and chronic osteomyelitis
How it works (simple explanation)
PURBAC works by attacking bacteria in two linked steps. The source explains that co-trimoxazole blocks two enzymes involved in the production of folinic acid inside the micro-organism. In everyday language, this means the bacteria cannot make an important substance they need in order to survive and multiply.
Because the two ingredients work together, the combination can kill bacteria more effectively than either ingredient might do alone in some situations. The source also explains that this combined action may help when bacteria are resistant to one of the two ingredients on its own, and it may reduce the chance of bacterial resistance developing.
That does not mean it will work for every infection. It is intended for the infections specifically listed in the source, and it should be used exactly as prescribed.
Who should NOT use this medicine
Do not use if you…
Do not use PURBAC if you:
- have porphyria
- have liver parenchymal damage
- have megaloblastic anaemia due to folic acid deficiency
- have severe renal insufficiency
- have ever had a hypersensitivity (allergic reaction) to sulphonamides or trimethoprim
- are pregnant
- are a woman prior to delivery
- are breastfeeding
- are giving it to a premature infant
- are giving it to a newborn infant during the first few weeks of life
Extra caution for the paediatric suspension
Do not give PURBAC PAEDIATRIC SUSPENSION if the child has certain rare inherited problems involving sugar handling, namely:
- fructose intolerance
- glucose-galactose malabsorption
- sucrase-isomaltase insufficiency
Warnings and precautions (Read before use)
Important safety points before you start
Some people have a higher chance of side effects with PURBAC. The source says that side effects occur more often in immunocompromised patients, such as people with AIDS or those receiving immunosuppressive therapy. In these patients, problems can include skin rash, repeated fever, low white blood cell counts, low platelet counts, and raised liver enzyme values.
Stop treatment straight away if you get a rash
This is one of the most important warnings in the source.
Warning: If a rash appears while you are taking PURBAC, treatment should be stopped immediately because severe allergic reactions can occur. The source also notes that PURBAC may cause very serious skin reactions, including erythema multiforme, toxic dermal necrolysis, and allergic vasculitis.
If you may have folate deficiency
PURBAC should be used carefully if you have actual or possible folate deficiency. The trimethoprim part of the medicine can interfere with folate metabolism, and the source says folinic acid could be considered.
It should also be used with caution if you are receiving pyrimethamine, because you may develop megaloblastic anaemia linked to the trimethoprim component.
Older adults, malnutrition, and blood monitoring
Side effects affecting the blood may be more severe in:
- elderly patients
- malnourished patients
There may also be a higher risk of thrombocytopenia in elderly patients who are using diuretics, especially thiazides, at the same time.
If you are on prolonged treatment, the source says you should have regular blood examinations.
Kidney problems and fluid intake
PURBAC should be used carefully and at a reduced dose if you have impaired kidney function. The source also warns about crystalluria (crystals forming in the urine), especially with very large doses. To lower this risk, it says you should maintain adequate fluid intake. In some cases, alkalis may be necessary if very large doses are used.
Diabetes and sugar content in the suspension
PURBAC PAEDIATRIC SUSPENSION contains sucrose, and this may affect glycaemic control in patients with diabetes mellitus.
Driving and using machines
Not specified in the source.
Alcohol
Not specified in the source.
Pregnancy, planning pregnancy, and breastfeeding
PURBAC should not be used during pregnancy, before delivery, or by nursing mothers. The same warning appears in both the contraindications and human reproduction sections of the source.
If you are pregnant, planning a pregnancy, close to delivery, or breastfeeding, speak to your doctor or pharmacist before taking any dose. This medicine is also not for premature infants or newborn infants in the first few weeks of life.
Interactions
PURBAC can interact with a number of medicines and even with some lab tests. It is a good idea to tell your doctor, nurse or pharmacist about everything you are taking, including chronic medicines, over-the-counter products, and any recent treatments.
Medicines that may interact
The source mentions the following interactions:
- Some diuretics, especially:
- acetazolamide
- thiazides
- Sulphonylurea medicines used to lower blood sugar
- Oral anticoagulants
- Warfarin
- Methotrexate
- Phenytoin
- Digoxin
- Procainamide
- Tolbutamide
- Cyclosporine
- Pyrimethamine
- Paraldehyde
- Para-aminobenzoic acid and related compounds
- Local anaesthetics from the procaine group
What these interactions may mean in practice
According to the source:
- sulphamethoxazole may increase the effects of oral anticoagulants, methotrexate and phenytoin
- trimethoprim may increase the anticoagulant effect of warfarin
- trimethoprim may also prolong the half-life of phenytoin
- high doses of sulphamethoxazole may have a blood sugar-lowering effect
- the antidiabetic effect of sulphonylurea medicines may be increased
- trimethoprim may interact with digoxin, procainamide and tolbutamide by affecting how the body clears them
- reversible worsening of kidney function has been reported with trimethoprim and cyclosporine after kidney transplantation
- paraldehyde may increase the acetylation of sulphamethoxazole and raise the risk of crystalluria
- the action of sulphamethoxazole may be reduced by para-aminobenzoic acid and related compounds, especially procaine-type local anaesthetics
Test interference
PURBAC may interfere with some diagnostic tests, including tests for:
- urea
- creatinine
- urinary glucose
- urobilinogen
- serum methotrexate (where dihydrofolate reductase is used)
- the Jaffe reaction for creatinine
Note: If you are going for blood tests or urine tests, tell the healthcare professional that you are taking PURBAC.
Food and spacing advice
The source says tablets are taken after meals. It does not provide any special spacing advice with foods or other medicines beyond the interactions listed.
How to take (Step-by-step)
General use
Take PURBAC exactly as prescribed. Do not change the dose on your own.
For tablets, the source says they are taken every 12 hours after meals. For the paediatric suspension, the bottle should be shaken before use.
Adults and children over 12 years
The usual dose is:
- two PURBAC ADULT tablets every 12 hours after meals, or
- one PURBAC DOUBLE STRENGTH tablet every 12 hours after meals
For particularly severe cases, the maximum dose is:
- three PURBAC ADULT tablets every 12 hours, or
- one and a half PURBAC DOUBLE STRENGTH tablets every 12 hours
For long-term treatment lasting more than 14 days, the minimum dose is:
- one PURBAC ADULT tablet every 12 hours, or
- half a PURBAC DOUBLE STRENGTH tablet every 12 hours
Children 6 to 12 years
For PURBAC ADULT tablets, the dose is:
- one tablet every 12 hours after meals
For PURBAC PAEDIATRIC SUSPENSION, the recommended structure is based on body mass, but the source gives the practical age-based dose as:
- 10 ml twice daily for children aged 6 to 12 years
How long to take it
For acute infections, PURBAC should be taken:
- for at least 5 days, or
- for at least 2 days after symptoms have disappeared
If there is no obvious clinical improvement after 7 days, the patient should be reassessed.
Dosing in renal impairment
If you have kidney impairment and PURBAC is still indicated, the source suggests the following based on creatinine clearance:
- Above 25 ml/min: standard dose
- 15 to 25 ml/min: standard dose for a maximum of 3 days, then half the standard daily dose
- Below 15 ml/min: do not use unless haemodialysis facilities are available; then half the standard daily dose may be given
For these patients, plasma sulphamethoxazole concentrations are recommended every 2 days using samples taken 12 hours after dosing. If total sulphamethoxazole is above 150 µg/ml, treatment should be interrupted until it falls below 120 µg/ml.
Missed dose
Not specified in the source.
Overdose
Possible symptoms of overdose are the same kind of symptoms listed under side effects. Treatment is symptomatic and supportive.
Simple adherence tips based on the source
Because the source says PURBAC is usually taken every 12 hours after meals, it may help to tie your doses to regular morning and evening meals. Keep using it for the full prescribed period, even if you start feeling better earlier, unless your doctor tells you to stop or you develop a rash.
Dosing table
| Age or weight | Dose | Frequency | Maximum daily dose | |
|---|---|---|---|---|
| Children 6 to 12 years (PURBAC ADULT tablets) | 1 tablet | Every 12 hours after meals | Not specified in the source | |
| Adults and children over 12 years | 2 PURBAC ADULT tablets or 1 PURBAC DOUBLE STRENGTH tablet | Every 12 hours after meals | Usual dose stated; see severe-case maximum below | |
| Adults and children over 12 years, particularly severe cases | 3 PURBAC ADULT tablets or 1½ PURBAC DOUBLE STRENGTH tablets | Every 12 hours | This is the maximum dose stated for particularly severe cases | |
| Long-term treatment longer than 14 days | 1 PURBAC ADULT tablet or ½ PURBAC DOUBLE STRENGTH tablet | Every 12 hours | Not specified in the source | |
| Children 6 to 12 years (PURBAC PAEDIATRIC SUSPENSION) | 10 ml | Twice daily | Not specified in the source | |
| Paediatric dosing structure | 6 mg trimethoprim + 30 mg sulphamethoxazole per kg body mass daily | Daily total basis | Not specified in the source |
Possible side effects
Like all medicines, PURBAC can cause side effects. Some are mild and some are serious. Skin reactions and stomach-related side effects are among the more common problems mentioned in the source.
Common
The source says hypersensitivity reactions involving the skin are among the most common side effects, and gastrointestinal side effects can also occur fairly frequently. Examples mentioned include:
- skin rash
- itching (pruritus)
- nausea
- vomiting
- diarrhoea
- sore mouth
Less common
Other side effects listed in the source include:
- photosensitivity reactions
- exfoliative dermatitis
- erythema nodosum
- fever
- dizziness
- fatigue
- headache
- insomnia
- vertigo
- ataxia
- peripheral neuritis
- hypothyroidism
- eye effects such as transient myopia or optic neuropathy
- altered gut bacterial flora, with the possibility of pseudomembranous colitis
- lumbar pain
- blood in the urine (haematuria)
- low urine output (oliguria)
- no urine output (anuria) due to crystallisation in the urine
Serious—seek urgent help
Get urgent medical help if you develop symptoms that may suggest a serious reaction. These include:
- a rash, especially if it is severe or spreading
- severe skin reactions such as:
- Stevens-Johnson syndrome
- Lyell’s syndrome / toxic epidermal necrolysis
- severe erythema multiforme
- anaphylaxis
- signs of serious blood problems such as:
- agranulocytosis
- aplastic anaemia
- thrombocytopenia
- leucopenia
- hypoprothrombinaemia
- eosinophilia
- acute haemolytic anaemia, especially if associated with glucose-6-phosphate dehydrogenase deficiency
- kidney-related hypersensitivity reactions that may lead to renal failure
- liver-related toxicity (hepatotoxic reactions)
- myocarditis
- pancreatitis
- pulmonary eosinophilia
- vasculitis, including polyarteritis nodosa
- cyanosis caused by methaemoglobinaemia or sulphaemoglobinaemia
Warning: The source specifically states that treatment should be discontinued immediately when a rash appears.
Storage and disposal
Store PURBAC:
- at or below 25 °C
- protected from light
- protected from moisture
- in the original packaging until needed for use
- out of the reach of children
Expiry
Expiry guidance is not specified in the source beyond normal storage instructions. Do not use medicine that is past its expiry date. Not specified in the source.
Disposal
Disposal instructions are not specified in the source.
What the medicine contains
Active ingredients
- PURBAC ADULT: 80 mg trimethoprim + 400 mg sulphamethoxazole per tablet
- PURBAC DOUBLE STRENGTH: 160 mg trimethoprim + 800 mg sulphamethoxazole per tablet
- PURBAC PAEDIATRIC SUSPENSION: 40 mg trimethoprim + 200 mg sulphamethoxazole per 5 ml
Other ingredients mentioned in the source
PURBAC ADULT and PURBAC DOUBLE STRENGTH contain excipients including:
- hydrogenated vegetable oil
- magnesium stearate
- microcrystalline cellulose
- Nipastat
- pregelatinised starch
- sodium starch glycolate
- starch maize
Both tablet products are stated to be sugar free and contain Nipastat 0.02% m/m as preservative.
PURBAC PAEDIATRIC SUSPENSION contains:
- aluminium magnesium silicate
- aniseed oil
- carmellose sodium
- colour erythrosine powder (C.I. 45430)
- ethanol
- Nipastat
- polysorbate
- purified water
- sodium cyclamate
- sucrose
It contains:
- sucrose 3 g
- sodium cyclamate 20 mg
- Nipastat 0.3% m/v as preservative
Pack information and appearance
What the different forms look like
- PURBAC ADULT: flat white tablet with bevelled edges, engraved with the Lennon logo on one side and “PURBAC” on the other
- PURBAC DOUBLE STRENGTH: white, oval, biconvex tablet, scored on one side and marked “C24” on the other
- PURBAC PAEDIATRIC SUSPENSION: pink, viscous suspension with a pourable consistency and a characteristic aniseed smell
Pack sizes mentioned in the source
PURBAC ADULT may be supplied in packs of:
- 20 tablets
- 100 tablets
- 1 000 tablets
- 28 tablets in patient-ready packaging
PURBAC DOUBLE STRENGTH may be supplied in packs of:
- 10 tablets
- 30 tablets
- 250 tablets
- 28 tablets in patient-ready packaging
PURBAC PAEDIATRIC SUSPENSION may be supplied in bottles of:
- 50 ml
- 100 ml
- 500 ml
Not all pack sizes are necessarily marketed.
Practical FAQs (based ONLY on the source)
Can I take PURBAC on an empty stomach?
The source says the tablets are taken after meals. It does not say to take them on an empty stomach.
Can my child use the paediatric suspension?
For children aged 6 to 12 years, the source gives a dose of 10 ml twice daily. It also says the bottle should be shaken before use. This product should not be used in premature infants or newborn infants during the first few weeks of life.
What should I do if I get a skin rash?
Stop treatment immediately and get medical advice as soon as possible. The source gives a strong warning because serious allergic skin reactions can happen.
Can I take PURBAC for a long time?
It can be used for longer treatment in some cases, because the source gives a minimum dosage for treatment lasting more than 14 days. If you are on prolonged treatment, regular blood examinations are recommended.
How long should I keep taking it for an acute infection?
The source says to use it for at least 5 days, or for at least 2 days after symptoms disappear.
What if I do not feel better after a week?
If there is no clinical improvement after 7 days, the patient should be reassessed.
Can I use it if I am pregnant or breastfeeding?
No. The source says PURBAC should not be used during pregnancy, before delivery, or while breastfeeding.
Can I drink alcohol while taking this?
Not specified in the source.
Can this medicine affect my blood sugar?
The source says the paediatric suspension contains sucrose, which may affect glycaemic control in people with diabetes mellitus. It also says high doses of sulphamethoxazole may have a hypoglycaemic effect, and the effect of sulphonylurea antidiabetic medicines may be enhanced.
Do I need to tell the lab I am taking PURBAC?
Yes. The source says it may interfere with certain diagnostic tests, including tests for urea, creatinine, urinary glucose, urobilinogen, serum methotrexate and the Jaffe creatinine reaction.
Plain-language summary
PURBAC contains trimethoprim and sulphamethoxazole and is used for a range of bacterial infections listed in the source. If you are taking it, use it exactly as prescribed, usually every 12 hours after meals, and complete the full course for as long as your healthcare professional tells you. If you are using the paediatric suspension, shake the bottle before use.
The biggest safety point to remember is this: stop the medicine immediately if a rash appears and seek medical advice urgently. Also make sure your doctor knows if you have kidney problems, folate deficiency, diabetes, or if you take medicines such as warfarin, phenytoin, methotrexate, diuretics or diabetes tablets. Do not use PURBAC if you are pregnant, breastfeeding, allergic to its ingredients, or if it is intended for a premature or very young newborn baby.
