Drug Interaction:
Interacting drugs- Sulphamethoxazole - summary
Sulphamethoxazole +
Anticoagulants
increase the anticoagulant effect of warfarin and anisindione
due to anticoagulants hepatic metabolism. Increase the risk of bleeding
Ritonavir
the AUC ofsulfamethoxazole was decreased by 20%.
+ Sulphamethoxazole/Trimethoprim
Indinavir
coadmin for 1 week resulted in a 19% increase in trimethoprim AUC and
no change in sulfamethoxazole AUC
Ganciclovir
cytotoxic drugs inhibit replication of cells . Therefore,consider
concomiitant use of dapsone, pentamidine, flucytosine, vincristine,
vinblastine, adriamysin, amphotericin B, trimethoprim,
sulphamethoxazole combinations, only if potential benefits outweigh
the risks
Trimethoprim and Sulphamethoxazole + (TMP-SMZ)
Anticoagulants
prothrombin time of warfarin prolonged. Monitor coagulation
tests and adjust dosage as required
Cyclosporine
a decrease in the therapeutic effect of cyclosporine and an increased
risk of nephrotoxicity have occured.
Dapsone + TMP-SMZ or TMP-SMZ + Dapsone
increased serum levels of both dapsone and TMP may occur
Diuretics
in elderly patients, concomittamt use has increased incidence of
thrombocytopenia with purpura
Hydantoins
phenytoins hepatic clearance may be decreased and half-life
prolonged
Methotrexate
sulfonamides can displace methotrexate (MTX) from plasma protein
binding sites thus increasing the MTX concentrations, bone marrow
depressants effects may be potentiated.
Sulfonylureas
the hypoglycemic response may be increased
Zidovudine
the serum levels of zidovudine may be increased due to decreased
renal clearance.
Atovaquone
coadministration resulted in a decrease in average steady-state
concentratons of TMP and SMZ in plasma, respy. However, this effect,
is minor and would not be expectedc to produce any clinically
significant values
Indication:
Urinary tract infections
Adverse Reaction:
Parenntral therapy- local reaction, pain and slight irritation on IV administration, thrombophlebitis (rare)
Most common- GI disturbances (nausea, vomiting, anorexia) alleregic skin reactions (eg. rash, urticaria)
Hematologic- agranulocytosis, aplastic, hemolytic or megaloblastic anemia, thrombocytopenia, leukopenia, hyproprothrombinemia,eosionophilla, methomoglobinemia, hyperkalemai, hyponatremia.
Hypersensitivity- erythema multoforme, Stevens-Johnson Syndrome, generalised skin eruptions, rash, toxic epidermal necrolysis, urticaria, serum sickness-like syndrome, priritus, exfoliative dermatitis, anaphylactoid reactions, conjunctival and scleral injection,photosensitization, allergic myocarditis,
angioedema, drug fever, chills.
GI- glossitis, anorexia, stomatisis, nausea, emesis, abdominal pain, diarrhea, pseudomembranous enterocolitis,hepatitis (including cholestatic jaundice and hepatic necrosis), pancreatitis, elevation of serum ytransaminase and bilirubin.
CNS- headche, mental depression, convulsions, ataxia, hallucinations, tinnitus, vertigo, insonia, apathy, fatigue,weakness, nervousness, aseptic menigitis, periphreral neuritis.
GU- renal failure, interstitial nephritis, BUn and serum creatinine elevation, toxic nephrosis with oliguria, and anuria, crystalluria
Musculoskeetal- arthalgia, myalgia.
Respiratory- pulmonary infiltrates
Contra-Indications:
Liver damage,blood dyscrasias,renal insufficiency,hypersens,infants.
Special precautions:
Pregnancy, lactation, elderly and in long tern therapy.
Glucose 6-phosphatedehydrogenase deficiency.
Special risk patients- use with caution in patients with possible folate deficiency( eg elderly patients, chronic alcoholics, anticonvulsnat therapy, malaabsorption syndrome, patients in malnutrion states)
Extracascular infiltration- if local irritation and inflammation due to to extravascular infiltration of the infusion occurs,discontinue the infusion and restart atanother site.
Superinfection- use of antibiotics (especially prolonged or repeated therapy may result in bacterial or fungal overgrowth of nonsusceptible organisms. Suchb overgrowth may lead to a secondary infection. Take appropiate measures if this occurs.
Sulfite sensitivity- sulfites may cause allergic-type reactions in susceptible persons.
Drug/Lab test interactions-
Trimethoprim can interfere with serum methotrexate assay determined by the competetive binding protein technique.
(CBPA). when a bacterial dihydrofolate reductase is used.
TMP+SMZ may interfere with a Jaffe alkaline picrate reaction assay, resulting in overestimation of about 10% in the normal value.
Warnings-
Streptococal pharynngitis- do not use to treat streptococcal pharyngitis.
Hematologic effects- sulfonamide-associated deaths although rare, have occured from hypersensitivity of the respiratory tract. Both TMP and SMZ can interfere hematopoiesis.
Obtain complete blood counts frequently.
Pneumocystis carini pneumonitis in patients with AIDS- because of the unique immune dysfunction, AIDS patient may not tolerate or respond to TMP+SMZ.The incidence of side effects, particularly rash, is greatly increased compared to non-AIDs patient
Renal/hepatic function- use with caution . Maintain adequate fluid intake.to prevent crystalluria and stone formation.
Elderly- theremay an increased risk of severe adverse reactions, particularly when complicating conditions exist eg, impaired kidney or liver function, concomittant use of other drugs
Pregnancy- Do not use at term. Sulfonamides readily cross the placenta.
Lactation- TMZ+ SMZ is not recommended. in the nursing poeriod because sulponamides are excreted in breast milk.
Children- not recommended for infants < 2 months old.
Dosages/ Overdosage Etc:
Indications
Urinary tract infections
Dosage-
Adults- 160mg TMP/800mg SMZ every 12 hours for 10 to 14 days ( 5days for shigellosis)
Children > 2 months of age- 8mg/kg TMP 40mg/kg SMZ per day given in 2 divided doses every 12 hours for 10 days
( 5 days for shigellosis)
Overdosage-
Symptoms
Acute- signa and symptoms with TMP or SMZ alone include anorexia, colic, vomiting, dizziness, headache, drowsiness, unconsciousness, pyrexia, maturia, crystalluria, depression, blood dyscarsias and jaundice.
Chronic- bone marrow depression, manifested as thrombocytopenia
Treatment
1. Usual supportive measures
2. Perform gastric lavage or emesis, force oral fluids and administer IV fluids if urine output is low and renal function is normal.
3. Acidifying urine will increase renal elimination of TMP
4. Monitor patient with blood dyscrasia and appropriate blood chemistries including electrolyte.
5. If significant blood dyscrasias or jaundice occurs, institute specific therapy for these complications.
6.Peritoneal dialysis is noteffective and hemodialysis is only moderately efective in eliminating TMP and SMZ
Missed dose-
1. If you miss a dose of this medicine, take it as soon as possible.
2. However, if it is almost time for next dose, skip the missed dose and go back to your
regular dosing schedule.
3. Do not double doses.
Other Information:
For Availability/supplies
Contact -
1.Indian Drug Manufacturers Association (IDMA)
Phone- 022- 24944624/ 24974308
Fax- 022- 24950723
Email- idma@vsnl.com
Website: www.idma-assn.org
2.Bulk Drug Manufacturers Association (India)(BDMA)
Phone - 040-23703910/ 23706718
Fax- 040-23704804
Email- info@bdmai.org
Website: www.info@bdmai.org
Patient Information:
1. Complete full course of therapy.
2. Maintain adequate fluid intake
3. Notify physician immediately if sore throat, fever, chills, pale skin, yellowing of skin oer eyes , rash, orunusual bleeding occurs.
4. Allergies- tell your doctor if you have ever had any unusual or allergic reaction to sulfa medicines, . Also tell your doctor if you are allergic to any other substances, such as foods, presevatives or dyes.
5.Pregnancy- sulfonamides are not recommended for use at the time of labor and delivery
6.Breast feeding- Sulfonamides and trimethoprim pass into breast milk and not recommended for use during breast feeding
7.Children- these combination should not be given to infants under 2 months of age unless directed by the childs doctor.
8. Elderly- elderly people are more sensitive to sulfonamide and trimethoprim combination.
9. Other medicines -
Acetoaminophen or
Amiodarone or
Anabolic steroids or
Androgens or
Antithyroid agents or
Carbamazepine or
Carmustine or
Chloroquine or
Dantrolene or
Daunorubicin or
Disulfram or
Divalproex or
Estrogens or
Etretinate or
Gold salts or
Mercaptopurine or
Naltrexone or
Oral contraceptives or
Other anti-infectives by mouth or
Phenothiazines or
Plicamycin or
Valproic acid - use of this combination may increase the chance of side effects affecting the liver
Antidiabetic , oral - use of this combination may increase the chance of side effects affecting the blood and/or the side effects of oral antidiabetics
10. Other medical problems -
Tell your doctor if you have any other medical problems especially -
Anemia or
G6PD- deficiency - patients with these problems may have an increase in side efects
affecting the blood.
Kidney disease or Liver disease - patients with liver disease may have an increased
chance of side effects.
Porphyria- this medicine may bring on an attack of porphyria
11. Missed dose -
If you miss a dose of this medicine, take it as soon as possible. however, if it is almost time for the next dose, skip the missed dose. Do not double doses.
12. Storage -
Keep out of reach of children. Store away from heat or direct sunlight. Do not store
the capsule in bathroom, near the kitchen sink, or in other damp places.
13. Outdated medicines -
Do not keep outdated medicine or medicine no longer needed. Be sure that any
discarded medicine is out of reach of children.
Pharmacology/ Pharmacokinetics:
Pharmacology-
Sulfametoxazole (SMZ) inhibits bacterial synthesis of dihydrofoilc acid by competing with para-aminobenzoic acid. Trimethoprim )TMP) blocks the production of tetrahydrofolic acid by inhibiting dihydrofolate reductase. Thus this combination blocks two consecutive steps in the bacterial biosynthesis of essential nucleic acids and proteins.
Pharmacokinetics-
TMP+ SMZ is rapidly and completely absorbed following oral,administration. Peak plasma levels occur in 1 to 4 hours following oral administration and 1 to 1.5 hours after IV infusion.
Pregnancy and lactation:
Pregnancy-
Do not use at term. Sulfonamides readily cross the placenta. Lactation- TMZ+ SMZ is not recommended. in the nursing poeriod because sulponamides are excreted in breast milk.
Children-
Not recommended for infants < 2 months old.
