Trimethoprim dosages

Trimethoprim has been reported to decrease the therapeutic effect of cyclosporine with a concomitant increased risk of nephrotoxicity. Increased levels of dapsone, warfarin, methotrexate, zidovudine, and sul-fonylureas may occur when given together with trimethoprim dosages of these drugs should be modified and the patient monitored accordingly. 

Another report describes a marked fall in white cell counts in renal transplant recipients during concurrent treatment with either co-trimoxazole (described as frequent) or trimethoprim (3 cases). In one case the fall occurred within 5 days and was managed by temporarily withdrawing the azathioprine and reducing the trimethoprim dosage from 300 to 100 mg daily. ... 

The application of various antibiotics such as rifampicin/tetracycline (63), cefatoxime/trimethoprim (64), or bacteriostatic compounds such as Micropur (Roth, Karlsruhe, Germany) (65) used for root pretreatment or added to collection media is another strategy to prevent biodegradation during root exudate collection. However, depending on dosage and plant species, also phytotoxic effects of antibiotics have been reported (Table 3). Antibiotics in the soil environment... 

Elsborg L Malabsorption in small intestinal diverticulosis treated with a low dosage sul-phonamide-trimethoprim. Dan Med Bull 1977 24 33-35. 

The most common adverse effects of lamivudine seen at doses used to treat HBV are mild they include headache, malaise, fatigue, fever, insomnia, diarrhea, and upper respiratory infections. Elevated alanine aminotransferase (ALT), serum lipase, and creatine kinase may also occur. The safety and efficacy of lamivudine in patients with decompensated liver disease have not been established. Dosage adjustment is required in individuals with renal impairment. Coadministration of trimethoprim-sulfamethoxazole decreases the renal clearance of lamivudine. 

Zidovudine should be used cautiously with any other agent that causes bone marrow suppression, such as interferon-a, trimethoprim-sulfamethoxazole, dap-sone, foscarnet, flucytosine, ganciclovir, and valganci-clovir. Probenecid and interferon-p inhibit the elimination of zidovudine therefore, a dosage reduction of zidovudine is necessary when the drugs are administered concurrently. Ribavirin inhibits the phosphorylation reactions that activate zidovudine, and zidovudine similarly inhibits the activation of stavudine thus, the coadministration of zidovudine with ribavirin or stavudine is contraindicated. 

Lamivudine is associated with an increased risk of pancreatitis in children and should be used with great caution in children who have had pancreatitis or are at high risk for it. Dosage adjustment is necessary in patients with renal impairment. Lamivudine should not be used in combination with zalcitabine, because they inhibit each other s activation by phosphorylation. Trimethoprim inhibits the renal elimination of lamivudine. 

Alert All dosage forms have same 5 1 ratio of sulfamethoxazole (SMX) to trimethoprim (TMP). 

Pentamidine is a well-established alternative therapy for pulmonary and extrapulmonary disease caused by P jiroveci. The drug has somewhat lower efficacy and greater toxicity than trimethoprim-sulfamethoxazole. The standard dosage is 3 mg/kg/d intravenously for 21 days. Significant adverse reactions are common, and with multiple regimens now available to treat P jiroveci infection, pentamidine is best reserved for patients with severe disease who cannot tolerate or fail other drugs. 

In another experiment with rainbow trout given oral trimethoprim at different dosage levels, the elimination half-life in plasma was found to be approxi-... 

In Atlantic salmon given feed containing trimethoprim at a dosage equivalent to 30 mg/kg bw/day for 10 days, residue concentrations in plasma peaked at around 12 ppm from day 7 to 10. Mean residue concentration in muscle was 10,740 ppb immediately after the end of treatment and declined to 100 ppb and 10 ppb after 300 and 400 days, respectively. 

It is important to consider the influence of interaction between functional groups of drugs that leads to their habit modification when formulated in suspension dosage form. Proton transfer from the N atom of sulfamethoxazole to the pyrimidine basic N1 atom of trimethoprim has been reported to occur in their equimolar complexes. Bettinetti et al. have reported nucleation of the complex of trimethoprim and sulfa-methoxypyridazine (1 1) to be accelerated by water or wet granulation. Our studies on cotrimoxazole (unpublished results) revealed immediate formation of fine needle-shaped crystals irrespective of the initial shape of sulfamethoxazole and trimethoprim crystals as a result of the interaction between the two drugs in suspension form. Small needles (Fig. 6A) were... 

According to studies on animals, tetroxoprim, which is structurally similar to trimethoprim, has stronger antikaliuretic effects than trimethoprim. Tetroxoprim-induced hyperkalemia has not been described yet. However, tetroxoprim is only rarely used and dosages are low (73). Trimethoprim uncommonly causes hyponatremia. 

Nausea and possibly vomiting occur in a few to 20% of adult patients taking normal dosages of co-trimoxazole (13,94). With trimethoprim alone in a dose of up to 400 mg/day, gastrointestinal tolerance was better and skin reactions were less frequent than with the combination (3). A review of the data from five different centers has shown that gastrointestinal complaints are less frequent with trimethoprim than with the combination (9). 

In one pharmacokinetic study in eight HIV-infected subjects, the renal clearance of zidovudine was significantly reduced by trimethoprim (201). The authors concluded that zidovudine dosages may need to be reduced if trimethoprim is given to patients with impairment of liver function or glucuronidation. Zidovudine, on the other hand, did not alter the pharmacokinetics of trimethoprim. 

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