What is Purbac?
Purbac is a brand name for the antibiotic co-trimoxazole, which combines two active ingredients: sulfamethoxazole and trimethoprim. This dual-ingredient formulation is effective against a broad spectrum of bacteria, including many Gram-positive and Gram-negative organisms. The combination is often more effective than either drug used alone, and it helps minimize the risk of bacterial resistance. It is available in various forms, including tablets (both adult and double-strength) and paediatric suspension. Purbac requires a prescription from a healthcare provider.
Primary Uses and Indications
What is Purbac used for? It is prescribed to treat a wide variety of bacterial infections in humans and, in some cases, can also be prescribed for pets by a veterinarian. A doctor's diagnosis is essential to determine if Purbac is the right course of treatment. The main uses of Purbac include:
- Urinary Tract Infections (UTIs): It is a common treatment for UTIs caused by susceptible bacteria.
- Respiratory Tract Infections: This includes conditions such as chronic bronchitis and Pneumocystis jiroveci pneumonia (PCP). PCP is a serious lung infection that is more common in individuals with weakened immune systems, such as those with HIV/AIDS.
- Middle Ear Infections (Otitis Media): It is used to treat middle ear infections caused by specific bacteria in children and adults.
- Intestinal Infections: Purbac can treat traveller's diarrhea and shigellosis (a type of bacillary dysentery).
- Skin and Soft Tissue Infections: It is indicated for the treatment of skin infections like pyoderma, boils, abscesses, and furuncles.
- Other Infections: Other uses include the treatment of nocardiosis, acute brucellosis, and as prophylaxis against PCP and toxoplasmosis in individuals with HIV/AIDS.
How Purbac Works
Purbac works by employing a two-pronged approach to inhibit bacterial growth. The two active components, sulfamethoxazole and trimethoprim, target different steps in the bacterial synthesis of folinic acid, a crucial compound for bacterial DNA replication and survival.
- Sulfamethoxazole: This component is a sulfonamide antibiotic. It acts as an antimetabolite, mimicking para-aminobenzoic acid (PABA) to inhibit the enzyme dihydropteroate synthetase. This prevents the conversion of PABA into dihydrofolic acid.
- Trimethoprim: This component inhibits the enzyme dihydrofolate reductase. This enzyme is responsible for converting dihydrofolic acid into tetrahydrofolic acid, the final product required for bacteria to produce purines and nucleic acids.
By blocking these two sequential steps in the same metabolic pathway, Purbac effectively stops the bacteria from reproducing and eventually kills them. This dual action makes it bactericidal and minimizes the risk of resistance compared to using a single drug.
Dosage and Administration
The appropriate dosage and duration of Purbac are determined by a healthcare professional based on factors such as the type and severity of the infection, the patient's age and weight, and the specific formulation used. It is crucial to follow the prescribing doctor's instructions precisely and to complete the full course of treatment, even if symptoms improve. Stopping the medication early can lead to a resurgence of the infection and potentially contribute to antibiotic resistance.
General Information on Administration
- The medication is available in different strengths and forms suitable for various age groups.
- For effective treatment, it is important to take the medication as directed by a healthcare professional.
- Purbac should generally be taken with a full glass of water to help maintain adequate hydration and can be taken with or without food, though taking it with food can help reduce potential stomach upset.
Potential Side Effects
Like all medications, Purbac can cause side effects. Some are common and mild, while others are rare but serious.
- Common Side Effects:
- Gastrointestinal upset (nausea, vomiting, diarrhea)
- Loss of appetite
- Skin rash or itching
- Headache
- Serious Side Effects (requires immediate medical attention):
- Severe allergic reactions (e.g., hives, swelling, difficulty breathing)
- Severe skin reactions, such as Stevens-Johnson syndrome
- Blood disorders (e.g., low platelet counts, anemia)
- Liver or kidney problems
- Hyperkalemia (high potassium levels)
Who Should Not Take Purbac
Purbac is not suitable for everyone. Certain medical conditions and concurrent medications can make its use dangerous.
- Hypersensitivity: Anyone with a known allergy to sulfonamides or trimethoprim should not take Purbac.
- Pregnancy and Breastfeeding: It is contraindicated during pregnancy due to potential risks to the fetus and should be avoided in breastfeeding mothers.
- Severe Organ Damage: Individuals with severe liver disease, significant kidney impairment (when monitoring is not possible), or certain haematological disorders should avoid Purbac.
- Infants: Purbac should not be given to infants under 2 months of age.
- Drug Interactions: Purbac can interact with many other drugs, including blood thinners like warfarin, certain diuretics, and ACE inhibitors. It is vital to inform your doctor of all medications you are taking.
Purbac vs. Other Antibiotics
| Feature | Purbac (Co-trimoxazole) | Nitrofurantoin | Ciprofloxacin (Cipro) |
|---|---|---|---|
| Drug Class | Sulfonamide and Antifolate Combination | Nitrofuran | Fluoroquinolone |
| Mechanism of Action | Inhibits folic acid synthesis | Damages bacterial DNA and proteins | Inhibits bacterial DNA gyrase and topoisomerase IV |
| Common Uses | UTIs, bronchitis, PCP, skin infections | UTIs | Severe infections, bone/joint infections, UTIs |
| Active Against | Wide range of Gram-positive and Gram-negative bacteria | Gram-positive and Gram-negative bacteria causing UTIs | Wide range of Gram-negative bacteria, some Gram-positive |
| Key Side Effects | Rash, GI upset, blood disorders | Nausea, headache, GI upset | Nausea, diarrhea, tendon rupture, nerve damage |
| Limitations | Not for viral infections; sulfa allergy risk | Mainly for UTIs; risk of lung and liver problems | Reserved for serious infections due to severe side effects; quinolone allergy risk |
Conclusion
Purbac is a potent and effective combination antibiotic used to treat various bacterial infections, including those affecting the urinary tract, lungs, and skin. It works by targeting two different steps in the bacteria's folic acid synthesis pathway, a strategy that helps to minimize resistance. However, it is a prescription-only medication and is not suitable for everyone, particularly those with sulfa allergies, severe organ dysfunction, or who are pregnant. Completing the full course of medication is vital for effective treatment and to prevent the development of antibiotic resistance. Always consult a healthcare professional for a proper diagnosis and treatment plan to ensure Purbac is the correct medication for your specific condition.
For more detailed prescribing information, refer to the South African Health Products Regulatory Authority (SAHPRA) repository for Purbac information.
