Trimethoprim-sulfamethoxazole

What is Trimethoprim-sulfamethoxazole?

• Trimethoprim-sulfamethoxazole (TMP/SMX) (Bactrim), also known as co-trimoxazole among other names, is a combination antibiotic used to treat a variety of bacterial infections.
• It consists of one part trimethoprim to five parts sulfamethoxazole.
• It is used for urinary tract infections, methicillin-resistant Staphylococcus aureus (MRSA) skin infections, travelers' diarrhea, respiratory tract infections, and cholera, among others.
• It may be used both to treat and prevent pneumocystis pneumonia and toxoplasmosis in people with HIV/AIDS and other causes of immunosuppression.
• It can be given by mouth or intravenously.

Trimethoprim and sulfamethoxazole

What are the uses of this medicine?

Trimethoprim-sulfamethoxazole (TMP/SMX) is used for:

• the treatment of urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis and Proteus vulgaris.
• the treatment of acute otitis media in pediatric patients due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae.
• the treatment of acute exacerbations of chronic bronchitis due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae.
• the treatment of enteritis caused by susceptible strains of Shigella flexneri and Shigella sonnei when antibacterial therapy is indicated.
• the treatment of documented Pneumocystis carinii pneumonia and for prophylaxis against Pneumocystis carinii pneumonia in individuals who are immunosuppressed.
• the treatment of traveler’s diarrhea due to susceptible strains of enterotoxigenic E. coli.

How does this medicine work?

• Trimethoprim-sulfamethoxazole (TMP-SMZ) is a combination of a sulfonamide antibiotic and a methoprim.
• This combination is widely used for therapy of infections due to susceptible bacteria as well as prevention of opportunistic infections with Pneumocystis jiroveci (formerly carinii) in immune deficient individuals.
• The two agents are synergistic in inhibition of folate synthesis – the sulfamethoxazole (sul" fa meth ox' a zole) inhibiting production of dihydrofolate from para-aminobenzoic acid, and the trimethoprim (trye meth' oh prim) inhibiting the next step in the pathway from dihydrofolate to tetrahydrofolate.

Who Should Not Use this medicine ?

This medicine cannot be used in patients:

• with a known hypersensitivity to trimethoprim or sulfonamides.
• with documented megaloblastic anemia due to folate deficiency.
• in pregnant patients and nursing mothers
• in pediatric patients less than 2 months of age.
• with marked hepatic damage or with severe renal insufficiency.

What drug interactions can this medicine cause?

• Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take.

Be sure to mention the following:

• amantadine
• angiotensin converting enzyme inhibitors such as benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), and trandolapril (Mavik)
• anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven)
• cyclosporine (Gengraf, Neoral, Sandimmune)
• oral diabetes medications such as glipizide (Glucotrol), glyburide (Diabeta, Glynase), metformin (Fortamet, Glucophage), pioglitazone (Actos), repaglinide (Prandin), rosiglitazone (Avandia)
• digoxin (Lanoxin)
• diuretics ('water pills')
• indomethacin (Indocin)
• leucovorin (Fusilev)
• medications for seizures such as phenytoin (Dilantin, Phenytek)
• memantine (Namenda)
• methotrexate (Trexall)
• pyrimethamine (Daraprim)
• tricyclic antidepressants such as amitriptyline (Elavil), amoxapine (Asendin), desipramine (Norpramin), doxepin (Adapin, Sinequan), imipramine (Tofranil), nortriptyline (Aventyl, Pamelor), protriptyline (Vivactil), and trimipramine (Surmontil).

Is this medicine FDA approved?

• Trimethoprim-sulfamethoxazole (TMP-SMZ) was approved for use as a combination antibiotic in the United States in 1973 and is still in wide use, more than 8 million prescriptions being filled yearly.
• TMP-SMZ is recommended for use in adults and children for urinary tract infections, bronchitis, sinusitis and otitis media and for prophylaxis against opportunistic infections due to parasites and pneumocystitis jiroveci.

How should this medicine be used?

Recommended dosage: Adults:

• The usual adult dosage in the treatment of urinary tract infections is 1 sulfamethoxazole and trimethoprim DS (double strength) tablet every 12 hours for 10 to 14 days.
• An identical daily dosage is used for 5 days in the treatment of shigellosis.

Children:

• The recommended dose for children with urinary tract infections or acute otitis media is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days.
• An identical daily dosage is used for 5 days in the treatment of shigellosis.

Acute Exacerbations of Chronic Bronchitis in Adults:

• The usual adult dosage in the treatment of acute exacerbations of chronic bronchitis is 1 sulfamethoxazole and trimethoprim double strength tablet or 2 sulfamethoxazole and trimethoprim tablets every 12 hours for 14 days.

Pneumocystis Carinii Pneumonia: Adults and Children:

• The recommended dosage for patients with documented Pneumocystis carinii pneumonia is 75 to 100 mg/kg sulfamethoxazole and 15 to 20 mg/kg trimethoprim per 24 hours given in equally divided doses every 6 hours for 14 to 21 days11.

Prophylaxis Adults:

• The recommended dosage for prophylaxis in adults is 1 sulfamethoxazole and trimethoprim DS (double strength) tablet daily12

Children:

• For children, the recommended dose is 750 mg/m2/day sulfamethoxazole with 150 mg/m2/day trimethoprim given orally in equally divided doses twice a day, on 3 consecutive days per week.

Traveler’s Diarrhea in Adults:

• For the treatment of traveler’s diarrhea, the usual adult dosage is 1 sulfamethoxazole and trimethoprim DS (double strength) tablet or 2 sulfamethoxazole and trimethoprim tablets every 12 hours for 5 days.

Administration:

• Trimethoprim-sulfamethoxazole comes as a tablet and a suspension (liquid) to take by mouth.
• It usually is taken two times a day but may be taken up to four times a day when used to treat certain severe lung infections.
• Shake the liquid well before each use to mix the medication evenly.
• Take co-trimoxazole until you finish the prescription, even if you feel better.
• Do not stop taking co-trimoxazole without talking to your doctor.
• If you stop taking co-trimoxazole too soon or skip doses, your infection may not be completely treated and the bacteria may become resistant to antibiotics.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As a Sulfamethoxazole and trimethoprim Double Strength tablets (white, scored, oblong), containing 800 mg sulfamethoxazole and 160 mg trimethoprim
• As a suspension (liquid)

This medicine is available in fallowing brand namesː

• Bactrim
• Bactrim® DS
• Septra
• Septra® DS
• Septra® Suspension
• Sulfatrim® Suspension

What side effects can this medication cause?

The most common side effects of this medicine include:

• nausea, vomiting, anorexia
• rash and urticaria

Trimethoprim-sulfamethoxazole may cause some serious side effects which may include:

• STEVENS-JOHNSON SYNDROME
• TOXIC EPIDERMAL NECROLYSIS
• FULMINANT HEPATIC NECROSIS
• AGRANULOCYTOSIS
• APLASTIC ANEMIA

What special precautions should I follow?

• In rare instances, a skin rash may be followed by a more severe reaction, such as Stevens-Johnson syndrome, toxic epidermal necrolysis, hepatic necrosis, and serious blood disorders. Clinical signs, such as rash, sore throat, fever, arthralgia, pallor, purpura or jaundice may be early indications of serious reactions.
• Sulfamethoxazole/Trimethoprim-induced thrombocytopenia may be an immune-mediated disorder. Severe cases of thrombocytopenia that are fatal or life threatening have been reported. Thrombocytopenia usually resolves within a week upon discontinuation of sulfamethoxazole and trimethoprim.
• The sulfonamides should not be used for treatment of group alpha beta-hemolytic streptococcal infections.
• Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including sulfamethoxazole and trimethoprim. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.
• If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.
• Patients should be counseled that antibacterial drugs including sulfamethoxazole and trimethoprim tablets should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold).
• When sulfamethoxazole and trimethoprim tablets are prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed.
• Patients should be instructed to maintain an adequate fluid intake in order to prevent crystalluria and stone formation.
• Diarrhea is a common problem caused by antibiotics which usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibiotic. If this occurs, patients should contact their physician as soon as possible.
• Cases of hypoglycemia in non-diabetic patients treated with sulfamethoxazole and trimethoprim are seen rarely, usually occurring after a few days of therapy. Patients with renal dysfunction, liver disease, malnutrition or those receiving high doses of sulfamethoxazole and trimethoprim are particularly at risk.
• As with all drugs containing sulfonamides, caution is advisable in patients with porphyria or thyroid dysfunction.
• plan to avoid unnecessary or prolonged exposure to sunlight and to wear protective clothing, sunglasses, and sunscreen. Co-trimoxazole may make your skin sensitive to sunlight.

What to do in case of emergency/overdose?

Symptoms of overdosage may include:

• anorexia
• colic
• nausea
• vomiting
• dizziness
• headache
• drowsiness
• unconsciousness
• Pyrexia
• hematuria
• crystalluria
• Blood dyscrasias
• jaundice
• mental depression
• confusion
• bone marrow depression

Management of overdosage:

• General principles of treatment include the institution of gastric lavage or emesis, forcing oral fluids, and the administration of intravenous fluids if urine output is low and renal function is normal.
• 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 not effective and hemodialysis is only moderately effective in eliminating sulfamethoxazole and trimethoprim.

Can this medicine be used in pregnancy?

• Pregnancy Category C.
• sulfamethoxazole and trimethoprim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Can this medicine be used in children?

• Sulfamethoxazole and trimethoprim is not recommended for infants younger than 2 months of age.

What are the active and inactive ingredients in this medicine?

Active:

• SULFAMETHOXAZOLE
• TRIMETHOPRIM

Inactives:

• MAGNESIUM STEARATE
• STARCH, CORN
• SODIUM STARCH GLYCOLATE TYPE A POTATO

Who manufactures and distributes this medicine?

Manufactured by:

• Vista Pharmaceuticals, Limited.
• Gopalaipalli –, India

For:

• Vista Pharmaceuticals, Inc.
• West Orange, NJ

Repackaged by:

• Proficient Rx LP
• Thousand Oaks, CA

What should I know about storage and disposal of this medication?

• TABLETS SHOULD BE STORED AT 20° TO 25° C (68° to 77°F) ).

• Dailymed label info on Trimethoprim-sulfamethoxazole
• FDA Trimethoprim-sulfamethoxazole

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