Consumer medicine information

1. Why am I using Bactrim^® 400/80?

Bactrim^® 400/80 contains the active ingredients sulfamethoxazole and trimethoprim. Bactrim^® 400/80 is used to treat infections where the oral dosage form of the antibiotic is not appropriate.
For more information, see Section 1. Why am I using Bactrim^® 400/80? In the full CMI.

2. What should I know before I use Bactrim^® 400/80?

Do not use if you have ever had an allergic reaction to Bactrim^® 400/80 or any of the ingredients listed at the end of the CMI.
Talk to your doctor if you have any other medical conditions, take any other medicines, or are pregnant or plan to become pregnant or are breast-feeding.
For more information, see Section 2. What should I know before I use Bactrim^® 400/80? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with Bactrim^® 400/80 and affect how it works.
A list of these medicines is in Section 3. What if I am taking other medicines? in the full CMI.

4. How do I use Bactrim^® 400/80?

Bactrim^® 400/80 will be administered to you by a doctor, nurse or other trained professional.
More instructions can be found in Section 4. How do I use Bactrim^® 400/80? in the full CMI.

5. What should I know while using Bactrim^® 400/80?

6. Are there any side effects?

Bactrim^® 400/80 may cause side effects in some people, some of which include severe skin rashes, allergy, bleeding and bruising, low blood sugar and kidney impairment.
For more information, including what to do if you have any side effects, see Section 6. Are there any side effects? in the full CMI.

1 Name of Medicine

Sulfamethoxazole/trimethoprim.

2 Qualitative and Quantitative Composition

Bactrim 400/80: One ampoule of 5 mL contains 80 mg trimethoprim and 400 mg sulfamethoxazole (=480 mg sulfamethoxazole/trimethoprim). Contains 2050 mg propylene glycol, 500 mg ethanol abs. and 58.55 mg sodium hydroxide.
Sulfamethoxazole is a white or almost white, crystalline powder. It is practically insoluble in water, freely soluble in acetone, sparingly soluble in ethanol (96%). It dissolves in dilute solutions of sodium hydroxide and in dilute acids. Melting point is 169-172°C. Trimethoprim is a white or yellowish-white powder. It is very slightly soluble in water, slightly soluble in ethanol (96%). Melting point is 199-203°C.
Excipient(s) with known effect. Alcohol 12.7% v/v.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Concentrate for solution for infusion. The concentrate is clear and colourless to slightly yellowish.

4 Clinical Particulars

4.9 Overdose

Acute. Symptoms. Signs and symptoms of overdosage with include anorexia, diarrhoea, colic, nausea, vomiting, dizziness, headache, mental and visual disturbances, drowsiness, and unconsciousness. Pyrexia, haematuria, anuria and crystalluria may be noted. Bone marrow depression (manifested as thrombocytopaenia or leucopaenia) and blood dyscrasias and jaundice are potential late manifestations of overdosage. Signs of acute overdosage with trimethoprim include nausea, vomiting, dizziness, headache, mental depression, confusion, and bone marrow depression.
Treatment. Stop therapy. Treatment of overdose is supportive and symptomatic care. Force fluids orally or parenterally if renal function is normal. In extreme overdosage in patients with impaired renal function, consider haemodialysis (peritoneal dialysis is ineffective) which is moderately effective in removing sulfamethoxazole and trimethoprim, monitoring of blood count and electrolytes. Acidification of the urine will increase renal elimination of trimethoprim. The patient should be monitored with blood counts and appropriate blood chemistries, including electrolytes. If a significant blood dyscrasia or jaundice occurs, specific therapy should be instituted for these complications. Peritoneal dialysis is ineffective.
Chronic. Use of sulfamethoxazole/trimethoprim at high doses and/or for extended periods of time may cause bone marrow depression manifested as thrombocytopenia, leukopenia, and/or megaloblastic anemia. If signs of bone marrow depression occur, the patient should be given leucovorin.
No known antidote for sulfonamide poisoning exists, however, calcium folinate (the equivalent of 3 mg to 6 mg folinic acid intramuscularly for 5 to 7 days) is an effective antidote for adverse effects in the haemopoietic system caused by trimethoprim.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.3 Preclinical Safety Data

Genotoxicity. No data available.
Carcinogenicity. No data available.

6 Pharmaceutical Particulars

6.7 Physicochemical Properties

Chemical structure. Sulfamethoxazole.
https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSSULFAM.gif Chemical name: 3-(4-aminobenzenesulfonamido)-5-methylisoxazole.
Molecular formula: C₁₀H₁₁N₃O₃S.
Molecular weight: 253.28.
CAS number. 723-46-6.
Chemical structure.Trimethoprim.
https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSTRIMET.gif Chemical name: 2, 4-diamino-5-(3, 4, 5-trimethoxybenzyl) pyrimidine.
Molecular formula: C₁₄H₁₈N₄O₃.
Molecular weight: 290.3.
CAS number. 738-70-5.

7 Medicine Schedule (Poisons Standard)

S4 - Prescription Only Medicine.

Summary Table of Changes

https://stagingapi.mims.com/au/public/v2/images/fulltablegif/BACCSIST.gif