Sulfadiazine

Toxicity

Oral LD50 in mouse is 1500 mg/kg.

Chemical properties

White to slightly yellow crystalline pow

Originator

Sulfadiazine,Lederle,US ,1941

The Uses of Sulfadiazine

It is used in the form of silver salts (sulfadiazine silver) as an external antibacterial agent, primarily for treating burns. It is believed that the presence of the silver ion in the molecule facilitates increased antimicrobial and wound-healing action.

The Uses of Sulfadiazine

Sulfonamide antibacterial.

The Uses of Sulfadiazine

DMSO soluble potent immunosuppressant, neuroprotective neuroregenerative, in vitro T cell proliferation blocker. disrupts calcineurin-mediated signal transduction in T lymphocytes

Background

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.

Indications

For the treatment of rheumatic fever and meningococcal meningitis

What are the applications of Application

Sulfadiazine is An antibacterial

Definition

ChEBI: A sulfonamide consisting of pyrimidine with a 4-aminobenzenesulfonamido group at the 2-position.

Manufacturing Process

5.4 parts of 2-amino-pyrimidine were covered with 15 parts of anhydrous pyridine. The reaction mixture was treated with 14 parts of pnitrobenzenesulfonyl chloride and the whole heated briefly on the steam bath and let stand 45 minutes at room temperature. To the reaction mixture were added 80 parts of hot alcohol and the precipitate was filtered off and washed with water. The solid was dissolved in dilute caustic solution and the solution was filtered, cooled and acidified. The 2-(p-nitrobenzenesulfonamido)- pyrimidine precipitated and was collected.
The crude 2-(p-nitrobenzenesulfonamido)-pyrimidine from the preceding step was suspended in 130 parts alcohol and 1.5 parts of concentrated hydrochloric acid were added. The suspension was then heated to reflux and 30 parts of iron powder were added with mechanical stirring. The mixture was refluxed and stirred for 24 hours with occasional addition of concentrated hydrochloric acid. The reaction mixture was then made slightly basic and filtered hot and the residues were extracted with several portions of boiling alcohol. The filtrate and wash solutions were combined and evaporated. The 2- (sulfanilamido)-pyrimidine was recrystallized from boiling water with decolorizing charcoal added, according to US Patent 2,410,793.

brand name

Coco-Diazine (Lilly); Eskadiazine (SmithKline Beecham).

Therapeutic Function

Antibacterial

Antimicrobial activity

Sulfadiazine is somewhat more active than other sulphonamides.

General Description

Sulfadiazine’s plasma half-life is 17 hours. It is a white,odorless crystalline powder soluble in water to the extentof 1:8,100 at 37°C and 1:13,000 at 25°C, in human serumto the extent of 1:620 at 37°C, and sparingly soluble in alcoholand acetone. It is readily soluble in dilute mineralacids and bases. Its pKa is 6.3.

Pharmaceutical Applications

Sulfadiazine is almost insoluble in water and unstable on exposure to light. It is administered orally or, as the sodium salt, by intravenous injection. It is a component of several multi-ingredient preparations. Its low solubility in urine led to its general replacement by other compounds. The intravenous solution is highly alkaline and should not be given by any other route.

Biochem/physiol Actions

Sulfadiazine is a sulfonamide antibiotic that blocks the synthesis of dihydrofolic acid by inhibiting the enzyme dihydropteroate synthase. Sulfadiazine is a competitive inhibitor of bacterial para-aminobenzoic acid (PABA), which is required for bacterial synthesis of folic acid. It is active against Gram positive bacteria, Gram negative bacteria and Chlamydia. Mode of resistance is via the alteration of dihydropteroate synthase or alternative pathway for folic acid synthesis.

Pharmacokinetics

Sulfadiazine is a sulfonamide antibiotic. The sulfonamides are synthetic bacteriostatic antibiotics with a wide spectrum against most gram-positive and many gram-negative organisms. However, many strains of an individual species may be resistant. Sulfonamides inhibit multiplication of bacteria by acting as competitive inhibitors of p-aminobenzoic acid in the folic acid metabolism cycle. Bacterial sensitivity is the same for the various sulfonamides, and resistance to one sulfonamide indicates resistance to all. Most sulfonamides are readily absorbed orally. However, parenteral administration is difficult, since the soluble sulfonamide salts are highly alkaline and irritating to the tissues. The sulfonamides are widely distributed throughout all tissues. High levels are achieved in pleural, peritoneal, synovial, and ocular fluids. Although these drugs are no longer used to treat meningitis, CSF levels are high in meningeal infections. Their antibacterial action is inhibited by pus.

Pharmacokinetics

Oral absorption： Very good
C_max 3 g oral： c. 50 mg/L after 3–4 h
Plasma half-life ：7–12 h
Volume of distribution： 0.36 L/kg
Plasma protein binding： c. 40%
Absorption and distribution
Adequate blood concentrations are easily achieved and maintained after oral administration. It is well distributed and penetrates in therapeutic concentrations into the CSF, but because of resistance it is no longer the drug of choice in meningitis. It crosses the placenta and enters breast milk to achieve concentrations around 20% of plasma levels.
Metabolism and excretion
Sulfadiazine is subject to acetylation in the liver. The acetyl derivative lacks antibacterial activity and is excreted more slowly (half-life 8–18 h). Parent compound and metabolite are both excreted mainly by glomerular filtration.

Clinical Use

Urinary tract infection
Nocardiasis
Chancroid
Toxoplasmosis (in combination with pyrimethamine)
Meningococcal infections
Prophylaxis of rheumatic fever

Side Effects

In addition to side effects common to the group, sulfadiazine inhibits the metabolism of phenytoin. The risk of crystalluria can be reduced by high fluid intake and alkalization of the urine.

Safety Profile

Poison by intravenous route. Moderately toxic by ingestion and intraperitoneal routes. Human systemic effects by ingestion: hematuria, anuria, general anesthesia, gastrointestinal effects. Experimental teratogenic and reproductive effects. When heated to decomposition it emits very toxic fumes of NOx and SOx.

Synthesis

Sulfadiazine, N1 -2-pyrimidinylsulfanilamide (33.1.7), is synthesized by reacting 4-acetylaminobenzenesulfonyl chloride with 2-aminopyrimidine, which gives an acetanilide derivative (33.1.6). The subsequent hydrolysis of this product with a base leads to the formation of the desired sulfadiazine.

Drug interactions

Potentially hazardous interactions with other drugs
Antibacterials: increased risk of crystalluria with methenamine.
Anticoagulants: effect of coumarins enhanced; metabolism of phenindione possibly inhibited.
Antiepileptics: antifolate effect and concentration of phenytoin increased.
Antimalarials: increased risk of antifolate effect with pyrimethamine.
Antipsychotics: avoid concomitant use with clozapine (increased risk of agranulocytosis).
Ciclosporin: reduced levels of ciclosporin; increased risk of nephrotoxicity.
Cytotoxics: increase risk of methotrexate toxicity

Metabolism

Not Available

Metabolism

Sulfadiazine is metabolised in the liver to the acetylated form, with elimination predominantly via the kidneys. Urinary excretion of sulfadiazine and its acetyl derivative is dependent on pH; when the urine is acidic about 30% is excreted unchanged in both fast and slow acetylators, whereas when the urine is alkaline about 75% is excreted unchanged by slow acetylators.