Sulfaphenazole

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Cat Number

API0231571

CAS Number

526-08-9

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Product Detail Description Scientific Support Customer Q&A

CAS Number

526-08-9

EINECS

208-384-3

Storage

Store at room temperature

Synonyms

Sulphaphenazole; Sulfabid; 4-Amino-N-(1-phenyl-1H-pyrazol-5-yl)benzenesulfonamide; Sulfafenazol; Sulfaphenazol; Sulfaphenazolum; Sulfafenazolo; 1-Phenyl-5-sulfanilamidopyrazole; 5-Sulfanilamido-1-phenylpyrazole

Molecular Formula

C15H14N4O2S

Molecular Weight

314.4

Smiles

C1=CC=C(C=C1)N2C(=CC=N2)NS(=O)(=O)C3=CC=C(C=C3)N

Appearance

White crystalline powder

Melting Point

179-183℃

Boiling Point

541.9±56.0℃ (Predicted)

Relative Density

1.39

General Description

Sulfaphenazole is a long-acting sulfonamide antibiotic used in the treatment of bacterial infections, including leprosy. It is an off-patent drug that functions as a potent inhibitor of the cytochrome P450 isoenzymes CYP 2C6 and CYP 2C9. It is a small molecule drug with a maximum clinical trial phase of IV.

Mechanism of Action

As a sulfonamide antibacterial, sulfaphenazole acts by competitively binding to the enzyme dihydropteroate synthase (DHPS), thereby inhibiting bacterial folate synthesis. This inhibition deprives the bacteria of folate, which is essential for DNA synthesis, ultimately preventing bacterial replication and leading to cell death. It also has reactive oxygen species scavenging properties.

Application

Sulfaphenazole has been indicated for a range of susceptible infections, including pneumonia, bronchitis, tonsillitis, otitis media, gonorrhea, diarrhea, cystitis, and pyelonephritis. It has also been used in the treatment of leprosy. Its contemporary clinical use is limited due to the availability of newer, safer, and more effective antibacterial agents.

A physiologically based pharmacokinetic (PBPK) model for tolbutamide, a CYP2C9 substrate, was optimized using SimCYP® and verified against the strong inhibitor sulfaphenazole, accurately predicting the 5.3–6.2‑fold increase in tolbutamide AUC. The model then prospectively predicted the interaction with tasisulam in cancer patients, yielding an AUC ratio of 4.7–5.4 versus the measured 5.7. This validated model can be applied to predict CYP2C9 interactions for novel inhibitors and illustrates the value of mechanistic PBPK modeling for overcoming challenges of clinical pharmacology studies in cancer populations.

Fig. 1 Observed and predicted plasma concentration–time profiles of tolbutamide in the absence of tasisulam. (Perkins EJ, et al., 2018)

References

Perkins EJ, et al. Physiologically Based Pharmacokinetic Modelling of Cytochrome P450 2C9-Related Tolbutamide Drug Interactions with Sulfaphenazole and Tasisulam. Eur J Drug Metab Pharmacokinet. 2018;43(3):355-367.

Does Sulfaphenazole require protection from light during long-term storage?

Yes, it is photosensitive. Light exposure can cause discoloration and degradation of the sulfonamide ring. Store in light-resistant containers.

What is the recommended storage temperature for Sulfaphenazole?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate hydrolysis and formation of sulfanilic acid derivatives.

Is Sulfaphenazole susceptible to moisture-induced degradation?

It is moderately hygroscopic. Under high humidity, it may hydrolyze, forming sulfanilamide and other impurities. Store with desiccant in tightly sealed containers.

How is the impurity sulfanilamide monitored during stability?

This primary degradation product is specifically quantified using a validated HPLC method, ensuring it remains below pharmacopoeial limits.