Sulfasalazine

AZULFIDINE

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Pronunciation: sul-fa-SAL-a-zeen

Sulfasalazine ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Sulfasalazine ballicule

Sulfasalazine AZULFIDINE mascot mnemonic cartoon — Visual mnemonic: Sulfasalazine mascot
**“Surfer sailor scene”**

What it isSulfapyridine linked to 5-ASA, split by colonic bacteria; ulcerative colitis and rheumatoid arthritis.

Why this oneTreats both bowel and joint disease, which is useful in spondyloarthropathy.

What limits itThe sulfapyridine causes most of the toxicity: rash, hemolysis in G6PD deficiency, and reversible oligospermia. Folate supplementation is needed.

Pearls

RA benefit takes 2–3 months.
CBC and LFTs every 2 weeks for 3 months: agranulocytosis, hepatitis.
Compatible with pregnancy and breastfeeding.
With methotrexate and hydroxychloroquine, triple therapy rivals adding a biologic.

Sulfasalazine molecular structure (skeletal formula) — Molecular structure: Sulfasalazine

FDA-approved for

ulcerative colitis/RA (~1950)

Principal riskHemolysis in G6PD deficiency; reversible oligospermia

Sulfonamide

Sulfonamide antimicrobial

Cleaved by colonic bacteria to sulfapyridine — a sulfonamide antimicrobial — plus 5-ASA, so expected to cross-react with the other sulfonamide antimicrobials; the attributed drug in 7% of RegiSCAR DRESS cases.

Open the sulfonamide hypersensitivity presentation → · sources [n] are on its References slide.

Classes and tags

Clinical profile

Therapeutic safety burden2 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryUnknown / historical label unavailable

Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.

FDA label

Read the full label on DailyMed ↗

NO BOXED WARNINGS

FDA dosing	Population	Start	Target	Max
Ulcerative colitis — initial therapy	Adults	1–2 g/day (to reduce GI intolerance)	3–4 g/day in evenly divided doses (intervals ≤8 h)	>4 g/day increases toxicity risk
Ulcerative colitis — initial therapy	Children ≥6 yr		40–60 mg/kg/day divided into 3–6 doses
Ulcerative colitis — maintenance	Adults		2 g/day
Ulcerative colitis — maintenance	Children ≥6 yr		30 mg/kg/day divided into 4 doses

Renal Give only after critical appraisal in renal damage; discontinue if renal function deteriorates.

Hepatic Give only after critical appraisal in hepatic damage.

Instructions

Take in evenly divided doses, preferably after meals
Maintain adequate fluid intake to prevent crystalluria
May cause orange-yellow discoloration of urine or skin

Available strengths

tab 500 mg
DR tab 500 mg

Contraindications

Intestinal or urinary obstruction
Porphyria
Hypersensitivity to sulfonamides or salicylates

Cautions

Hepatic, renal, and hematologic toxicity (deaths reported)
Serious infections
Oligospermia/infertility (reversible)
Use caution in severe allergy/bronchial asthma
G6PD deficiency (hemolytic anemia)

Adverse reactions

Anorexia
Headache
Nausea
Vomiting
Gastric distress
Reversible oligospermia
Rash

Pregnancy No clear fetal harm in animals; inhibits folic acid absorption (may affect NTD-preventive supplementation).

Lactation Undefined.

Cost

Sulfasalazine (AZULFIDINE)

What pharmacies pay · NADAC 9/30/26

Strength		#/mo	generic $/unit	CostPlus
500 mg	tab	per unit	$0.20/ea	offered

Generic entry1983

Active metabolites

Mesalamine

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Memory aids: interaction avatars

BCRP substrate

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Self-check

What splits sulfasalazine into its components?
Colonic bacteria.
Which component causes most sulfasalazine toxicity?
Sulfapyridine.