Antimicrobials
Trimethoprim-Sulfamethoxazole

Trimethoprim-Sulfamethoxazole

Low
Excellent
See below under General Info

Dosing

General Information

Hospital Formulary Status Yes (PO solid, PO susp, parenteral inj)

In-Hospital Cost will be updated

PharmaCare Formulary Status Yes (PO solid, PO susp, parenteral inj)

Special Authority None

PharmaCare Coverage 20/100mg PO - $0.1018/tab 80/400mg PO - $0.0521/tab 160/800mg PO DS - $0.2240/tab 16/80mg/ml IV ampul - $1.7690/ml 40/200mg/5ml PO susp - $0.2160/ml

Outpatient Cost 20/100mg PO - $0.11-0.96/tab 80/400mg PO - $0.05-0.58/tab 160/800mg PO DS - $0.13-3.60/tab 16/80mg/ml IV ampul - $1.77-1.95/ml 40/200mg/5ml PO susp - $0.22-0.24/ml

  •  Urinary tract infections
  •  Susceptible MRSA infections
  •  Stenotrophomonas infections
  •  Pneumocystis jirovecii pneumonia (Treatment or prophylaxis)

Follow creatinine and electrolytes in patients at increased risk renal failure, hyperkalemia.

Generally, well tolerated in patients without HIV (ADR rate: 6-8%) In patients with HIV, ADRs are common and severe (ADR rate: 25-50%)

Gastritis (PO and IV)

  •  sx: nausea, vomiting, and diarrhea
  •  common

Skin toxicity (PO and IV)

  •  common sx: rash and pruritus
  •  uncommon sx: mucosal membrane ulceration, erythema, scaling and skin detachment
  •  may involve SJS, exfoliative dermatitis and toxic epidermal necrolysis

Nephrotoxicity (mainly with IV)

  •  uncommon
  •  TMP decreases tubular secretion of creatinine, leading to increase in SCr that is not reflective of a true GFR reduction
  •  may include renal tubular acidosis and cholestatic or mixed liver injury
  •  usually reversible
  •  recovery: within a few weeks of discontinuation but some patients may experience prolonged recovery

Hyperkalemia (mainly with IV)

  •  caused by blockade of collecting tubule sodium channel by TMP
  •  more common in patients with HIV treated with high doses
  •  modest elevation in plasma potassium concentration can occur in patients without HIV with normal doses
  •  increased 7-day risk of sudden death in older patients receiving TMP-SMX and spironolactone, ACE inhibitor or ARB

Severe lactic acidosis (IV)

  •  usually resolves after discontinuation
  •  caused by propylene glycol, a solvent in IV TMP-SMX

Folate deficiency (mainly with IV)

  •  use with caution in patients with folate deficiency or at risk for complications of folate deficiency (pregnancy, chronic hemolytic anemia)
  •  TMP weakly inhibits human dihydrofolate reductase and reduces folate available for hematopoiesis
  •  may cause megaloblastic changes (macrocytic anemia, mild thrombocytopenia, leukopenia) when given over long periods or in high doses
  •  treatment: folic acid supplementation (except in patients with AIDS and Pneumocystis pneumonia)

Other

  •  hepatitis
  •  hypoglycemia
  •  hyponatremia
  •  hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency
  •  neutropenia

ACEi - Increased serum potassium level.

Increases amantadine levels.

Decreases cyclosporine.

Methotrexate- marrow suppression.

Increases phenytoin.

Increases rifampin.

Increases INR with warfarin.

Antimicrobial class: Sulfonamide, Antifolate

Pregnancy category: C

Average serum half life: 10.0 hr

Urine penetration: Therapeutic

Lung penetration: Therapeutic

CSF penetration: Therapeutic

Biliary penetration: Moderate