This study assessed the efficacy of pyrimethamine and sulfadiazine in treating mice infected with several atypical Toxoplasma gondii during an acute infection. A total of seven strains of Toxoplasma gondii were injected into Swiss mice. Treatment options for infected mice were pyrimethamine at 3-200 mg/kg per day, sulfadiazine at 10-640 mg/kg per day, or a lower dosage of a combination of the two medications. To assess the relationship between genotype and sensitivity to pyrimethamine and/or sulfadiazine, descriptive analysis was employed. The strains TgCTBr4 and TgCTBr17 (genotype 108) responded less well to pyrimethamine or sulfadiazine therapy. The strains TgCTBr1 and TgCTBr25 (genotype 206) were equally sensitive to PYR, but not to sulfadiazine therapy. The only strain that responds well to treatment with both medications is the TgCTBr9 strain (genotype 11) [1].

Absorption, Distribution and Excretion
Sulfadiazine is excreted largely in the urine.
Very limited penetration through the skin. Only when applied to very large area burns is absorption into the body generally an issue.

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Metabolism / Metabolites
Sulfadiazine has known human metabolites that include Sulfadiazine hydroxylamine.

Hepatotoxicity
Sulfadiazine, like other sulfonamides, causes a characteristic idiosyncratic liver injury which has features of drug-allergy or hypersensitivity. The typical onset is sudden development of fever and rash followed by jaundice within a few days or weeks of starting the medication. The pattern of injury is typically mixed, although fatal cases are often hepatocellular and prolonged cholestatic cases have also been described. Eosinophilia or atypical lymphocytosis are also common and the clinical pattern can be considered a part of DRESS syndrome (drug rash with eosinophilia and systemic symptoms). Cases of Stevens Johnson syndrome due to sulfadiazine have also been described. Sulfonamides such as sulfadiazine have been linked to many cases of acute liver failure and as a class, the sulfonamides still rank in the top 5 to 10 causes of drug induced, idiosyncratic fulminant hepatic failure. However, most cases of sulfonamide induced liver injury resolve rapidly, usually within 2 to 4 weeks unless cholestasis is severe. Onset of injury is more rapid with rechallenge and can appear within a day or reexposure. Patients with hepatic injury due to sulfadiazine may have a history of previous exposure to the drug without injury. Sulfonamides such as sulfadiazine can also cause mild and transient ALT elevations that do not progress to jaundice or more severe liver injury either alone or as a part of a generalized hypersensitivity reaction. Sulfonamides have also been linked to hepatic granulomas.

[1]. Kopmann C, et al. Abundance and transferability of antibiotic resistance as related to the fate of sulfadiazine in maize rhizosphere and bulk soil. FEMS Microbiol Ecol. 2013 Jan;83(1):125-34.
[2]. Silva LA, et al. Efficacy of sulfadiazine and pyrimetamine for treatment of experimental toxoplasmosis with strains obtained from human cases of congenital disease in Brazil. Exp Parasitol. 2019 Jul;202:7-14.

Sulfadiazine is a sulfonamide consisting of pyrimidine with a 4-aminobenzenesulfonamido group at the 2-position. It has a role as an antimicrobial agent, an antiinfective agent, a coccidiostat, an antiprotozoal drug, an EC 2.5.1.15 (dihydropteroate synthase) inhibitor, an EC 1.1.1.153 [sepiapterin reductase (L-erythro-7,8-dihydrobiopterin forming)] inhibitor, a xenobiotic, an environmental contaminant and a drug allergen. It is a member of pyrimidines, a sulfonamide, a substituted aniline and a sulfonamide antibiotic. It is functionally related to a sulfanilamide. It is a conjugate acid of a sulfadiazinate.
Sulfadiazine is an antibacterial prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the prevention and treatment of certain types of bacterial infections, including the treatment of chancroid, Toxoplasma gondii encephalitis, urinary tract infections, and other infections.
Toxoplasma gondii encephalitis can be an opportunistic infection (OI) of HIV.
One of the short-acting sulfonamides used in combination with pyrimethamine to treat toxoplasmosis in patients with acquired immunodeficiency syndrome and in newborns with congenital infections.
Silver sulfadiazine is a sulfa derivative topical antibacterial used primarily on second- and third-degree burns.
Sulfadiazine is a Sulfonamide Antibacterial.
Sulfadiazine is a sulfonamide antibacterial agent used in the therapy of mild-to-moderate infections due to sensitive organisms. Sulfadiazine, like other sulfonamides, is a well known cause of clinically apparent, idiosyncratic liver injury.
Sulfadiazine has been reported in Apis cerana with data available.
Sulfadiazine is a synthetic pyrimidinyl sulfonamide derivative, short-acting bacteriostatic Sulfadiazine inhibits bacterial folic acid synthesis by competing with para amino benzoic acid. It is used in combination with pyrimethamine to treat toxoplasmosis in patients with acquired immunodeficiency syndrome and in newborns with congenital infections. (NCI04)
Silver Sulfadiazine is a sulfonamide-based topical agent with antibacterial and antifungal activity. Silver sulfadiazine may act through a combination of the activity of silver and sulfadiazine. When this agent interacts with sodium chloride-containing body fluids, silver ions are released slowly and sustainably into wounded areas. Ionized silver atoms catalyze the formation of disulfide bonds leading to protein structural changes and inactivating thiol-containing enzymes; silver ions may also intercalate DNA thereby interfering with replication and transcription of bacteria. As a competitive inhibitor of para-aminobenzoic acid (PABA), sulfadiazine inhibits bacterial dihydropteroate synthase, thereby resulting in disruption of folic acid metabolism and ultimately DNA synthesis.
One of the short-acting SULFONAMIDES used in combination with PYRIMETHAMINE to treat toxoplasmosis in patients with acquired immunodeficiency syndrome and in newborns with congenital infections.
See also: Silver Sulfadiazine (has salt form); Sulfadiazine Sodium (has salt form); Sulfadiazine; Trimethoprim (component of) ... View More ...

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Drug Indication
For the treatment of rheumatic fever and meningococcal meningitis
Indicated as an adjunct for the prevention and treatment of wound sepsis in patients with second- and third-degree burns.

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Mechanism of Action
Sulfadiazine is a competitive inhibitor of the bacterial enzyme dihydropteroate synthetase. This enzyme is needed for the proper processing of para-aminobenzoic acid (PABA) which is essential for folic acid synthesis. The inhibited reaction is necessary in these organisms for the synthesis of folic acid.
Studies utilizing radioactive micronized silver sulfadiazine, electron microscopy, and biochemical techniques have revealed that the mechanism of action of silver sulfadiazine on bacteria differs from silver nitrate and sodium sulfadiazine. Silver sulfadiazine acts only on the cell membrane and cell wall to produce its bactericidal effect. A specific mechanism of action has not been determined, but silver sulfadiazine's effectiveness may possibly be from a synergistic interaction, or the action of each component. Silver is a biocide, which binds to a broad range of targets. Silver ions bind to nucleophilic amino acids, as well as sulfhydryl, amino, imidazole, phosphate, and carboxyl groups in proteins, causing protein denaturation and enzyme inhibition. Silver binds to surface membranes and proteins, causing proton leaks in the membrane, leading to cell death. Sulfadiazine is a competitive inhibitor of bacterial para-aminobenzoic acid (PABA), a substrate of the enzyme dihydropteroate synthetase. The inhibited reaction is necessary in these organisms for the synthesis of folic acid.

C10H10N4O2S

250.276

250.052

68-35-9

Sulfadiazine sodium;547-32-0;Sulfadiazine-d4;1020719-78-1;Sulfadiazine-13C6;1189426-16-1

5215

White to off-white solid powder

1.5±0.1 g/cm3

512.6±52.0 °C at 760 mmHg

253 °C (dec.)(lit.)

263.8±30.7 °C

0.0±1.3 mmHg at 25°C

1.679

-0.12

2

6

3

17

327

0

S(C1C([H])=C([H])C(=C([H])C=1[H])N([H])[H])(N([H])C1=NC([H])=C([H])C([H])=N1)(=O)=O

SEEPANYCNGTZFQ-UHFFFAOYSA-N

InChI=1S/C10H10N4O2S/c11-8-2-4-9(5-3-8)17(15,16)14-10-12-6-1-7-13-10/h1-7H,11H2,(H,12,13,14)

4-amino-N-pyrimidin-2-ylbenzenesulfonamide

RP 2616; RP2616; RP-2616

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ≥ 50 mg/mL (~199.78 mM)
H2O : < 0.1 mg/mL

Solubility in Formulation 1: ≥ 2.5 mg/mL (9.99 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 2.5 mg/mL (9.99 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (9.99 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)