APO-SULFATRIM PEDIATRIC TABLET

Sulfamethoxazole
Trimethoprim

Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.

Active Ingredient / Synonyms

3-(p-Aminophenylsulfonamido)-5-methylisoxazole | 3-Sulfanilamido-5-methylisoxazole | 4-Amino-N-(5-methyl-3-isoxazolyl)benzenesulfonamide | Gantanol (tn) | SMX | Sulfamethoxazole | Sulfamethoxazole |

Description

A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p208)

Indication

For the treatment bacterial infections causing bronchitis, prostatitis and urinary tract infections.

Mechanism of Action

Sulfonamides inhibit the enzymatic conversion of pteridine and p-aminobenzoic acid (PABA) to dihydropteroic acid by competing with PABA for binding to dihydrofolate synthetase, an intermediate of tetrahydrofolic acid (THF) synthesis. THF is required for the synthesis of purines and dTMP and inhibition of its synthesis inhibits bacterial growth. Pyrimethamine and trimethoprim inhibit dihydrofolate reductase, another step in THF synthesis, and therefore act synergistically with the sulfonamides.

Pharmacodynamics

Sulfamethoxazole is a sulfonamide drug that inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA) for binding to dihydropteroate synthetase (dihydrofolate synthetase). Sulfamethoxazole is bacteriostatic in nature. Inhibition of dihydrofolic acid synthesis decreases the synthesis of bacterial nucleotides and DNA. Sulfamethoxazole is normally given in combination with Trimethoprim, a dihydrofolate reductase inhibitor, which inhibits the reduction of dihydrofolic acid to tetrahydrofolic acid. Studies have shown that bacterial resistance develops more slowly with the combination of the two drugs than with either Trimethoprim or Sulfamethoxazole alone.

Pharmacokinetics

Absorption:

Rapidly absorbed following oral administration. Also well-absorbed topically.

Distribution:

Not Available

Metabolism:

Hepatic. The metabolism of sulfamethoxazole occurs predominately by N4-acetylation, although the glucuronide conjugate has been identified.

Elimination:

Not Available

Half-life

10 hours

Clearance

Not Available

Toxicity

Sulfamethoxazole may cause nausea, vomiting, diarrhea and hypersensitivity reactions. Hematologic effects such as anemia, agranulocytosis, thrombocytopenia and hemolytic anemia in patients with glucose-6-phosphate dehydrogenase deficiency may also occur. Sulfamethoxazole may displace bilirubin from albumin binding sites causing jaundice or kernicterus in newborns.

Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.

Active Ingredient / Synonyms

2,4-Diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine | 5-[(3,4,5-Trimethoxyphenyl)methyl]-2,4-pyrimidinediamine | Trimethoprim | Triméthoprime | Trimethoprimum | Trimetoprima | Trimethoprim |

Description

A pyrimidine inhibitor of dihydrofolate reductase, it is an antibacterial related to pyrimethamine. The interference with folic acid metabolism may cause a depression of hematopoiesis. It is potentiated by sulfonamides and the trimethoprim-sulfamethoxazole combination is the form most often used. It is sometimes used alone as an antimalarial. Trimethoprim resistance has been reported. [PubChem]

Indication

For the treatment of urinary tract infections, uncomplicated pyelonephritis (with sulfamethoxazole) and mild acute prostatitis. May be used as pericoital (with sulfamethoxazole) or continuous prophylaxis in females with recurrent cystitis. May be used as an alternative to treat asymptomatic bacteriuria during pregnancy (only before the last 6 weeks of pregnancy). Other uses include: alternative agent in respiratory tract infections (otitis, sinusitus, bronchitis and pneumonia), treatment of Pneumocystis jirovecii pneumonia (acute or prophylaxis), Nocardia infections, and traveller's diarrhea.

Mechanism of Action

Trimethoprim binds to dihydrofolate reductase and inhibits the reduction of dihydrofolic acid (DHF) to tetrahydrofolic acid (THF). THF is an essential precursor in the thymidine synthesis pathway and interference with this pathway inhibits bacterial DNA synthesis. Trimethoprim's affinity for bacterial dihydrofolate reductase is several thousand times greater than its affinity for human dihydrofolate reductase. Sulfamethoxazole inhibits dihydrofolate synthetase (aka dihydropteroate synthetase), an enzyme involved further upstream in the same pathway. Trimethoprim and sulfamethoxazole are commonly used in combination due to their synergistic effects. This drug combination also reduces the development of resistance that is seen when either drug is used alone.

Pharmacodynamics

Trimethoprim is a pyrimidine analogue that disrupts folate synthesis, an essential part of the thymidine synthesis pathway. Inhibition of the enzyme starves the bacteria of nucleotides necessary for DNA replication.The drug, therefore, exhibits bactericidal activity.

Pharmacokinetics

Absorption:

Readily and almost completely absorbed in the GI tract with peak serum concentrations attained 1-4 hours after oral administration. Widely distributed to tissues and fluids including kidney, lung, seminal fluid, aqueous humour, middle ear fluid, sputum, vaginal secretions, bile, bone and CSF.

Distribution:

Not Available

Metabolism:

Hepatic metabolism to oxide and hydroxylated metabolites.

Elimination:

Ten to twenty percent of trimethoprim is metabolized, primarily in the liver; the remainder is excreted unchanged in the urine. After oral administration, 50% to 60% of trimethoprim is excreted in the urine within 24 hours, approximately 80% of this being unmetabolized trimethoprim. Trimethoprim also passes the placental barrier and is excreted in human milk.

Half-life

8-11 hours in adults with normal renal function

Clearance

Not Available

Toxicity

LD50=4850 (orally in mice)

References

  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank

Although best effort has been made to ensure the information provided is correct and updated, users are advised to visit HSA Official website whenever in doubt. Please see Disclaimers.
We welcome all the content error reporting/feedback. Please contact us @ Text Us!

Approval Information

APO-SULFATRIM PEDIATRIC TABLET was registered with Health Science Authority of Singapore by PHARMAFORTE SINGAPORE PTE LTD. It is marketed with the registration number of SIN00508P with effective from 1988-04-28.

This product contains 100mg of Sulfamethoxazole, and 20mg of Trimethoprim in the form of TABLET.

The medicine was manufactured by APOTEX INC in CANADA

It is a Presciption Only Medicine which can only be obtained from a doctor or a dentist, or from a pharmacist with a prescription from a Singapore-registered doctor or dentist.

Anatomical Therapeutic Chemical (ATC) Classification

Products Containing as Single Ingredient

Drug IDTrade NameActive IngredientsForensic ClassRegistrantStatus
1DEXTROMETHORPHAN LINCTUS 15mg/5mlDextromethorphanP OnlyDRUG HOUSES OF AUSTRALIA PTE LTDActive
22ZENMOLIN SYRUP 2mg/5mlSalbutamolP OnlyDRUG HOUSES OF AUSTRALIA PTE LTDActive
41APO-PROPRANOLOL TABLET 40mgPropranololPOMPHARMAFORTE SINGAPORE PTE LTDActive
42APO-DIAZEPAM TABLET 2mgDiazepamPOMPHARMAFORTE SINGAPORE PTE LTDActive
44APO-DIAZEPAM TABLET 5mgDiazepamPOMPHARMAFORTE SINGAPORE PTE LTDActive
45APO-DIAZEPAM TABLET 10mgDiazepamPOMPHARMAFORTE SINGAPORE PTE LTDActive
46APO-PROPRANOLOL TABLET 10mgPropranololPOMPHARMAFORTE SINGAPORE PTE LTDActive
55APO-ISDN TABLET 10mgIsosorbide DinitratePOMPHARMAFORTE SINGAPORE PTE LTDActive
63DIAPO TABLET 10mgDiazepamPOMBEACONS PHARMACEUTICALS PTE LTDActive
64FURMIDE TABLET 40mgFurosemidePOMBEACONS PHARMACEUTICALS PTE LTDActive

Products Containing as Mixture Ingredient

Drug IDTrade NameActive IngredientsForensic ClassRegistrantStatus
4DIPHENHYDRAMINE EXPECTORANTAmmonium Chloride|Diphenhydramine|Sodium CitrateP OnlyDRUG HOUSES OF AUSTRALIA PTE LTDActive
5DIPHENHYDRAMINE EXPECTORANT PAED.Ammonium Chloride|Diphenhydramine|Sodium CitrateP OnlyDRUG HOUSES OF AUSTRALIA PTE LTDActive
400FAKTU SUPPOSITORYCinchocaine|PolicresulenP OnlyTAKEDA PHARMACEUTICALS (ASIA PACIFIC) PTE LTDActive
407TRIMAXAZOLE TABLETSulfamethoxazole|TrimethoprimPOMBEACONS PHARMACEUTICALS PTE LTDActive
435APO-SULFATRIM TABLETSulfamethoxazole|TrimethoprimPOMPHARMAFORTE SINGAPORE PTE LTDActive
508APO-SULFATRIM PEDIATRIC TABLETSulfamethoxazole|TrimethoprimPOMPHARMAFORTE SINGAPORE PTE LTDActive
526B.S. SUSPENSIONSulfamethoxazole|TrimethoprimPOMAPEX PHARMA MARKETING PTE LTDActive
583CO-TRIMEXAZOLE SUSPENSIONSulfamethoxazole|TrimethoprimPOMBEACONS PHARMACEUTICALS PTE LTDActive
676BANEOCIN OINTMENTBacitracin|NeomycinPOMNOVARTIS (SINGAPORE) PTE LTDActive
678BANEOCIN POWDERBacitracin|NeomycinPOMNOVARTIS (SINGAPORE) PTE LTDActive