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All about: Mesalamine (5-aminosalicylic acid, 5-ASA)

Big Image ( 5-aminosalicylic acid , 5-ASA ) Pronouncation: (me-SAL-a-meen)
Class: GI agent

Trade Names:
- Tablets, delayed-release 400 mg

Trade Names:
- Suppositories 1,000 mg

Trade Names:
- Tablets, delayed-release 1.2 g

Trade Names:
- Capsules, controlled-release 250 mg
- Capsules, controlled-release 500 mg

Trade Names:
- Enema 4 g per 60 mL

Mesacal (Canada)
Novo-5 ASA (Canada)
Salofalk (Canada)

Mechanism of Action


Reduces inflammation of colon topically by preventing production of substances involved in inflammatory process, such as arachidonic acid.



Approximately 28% is absorbed; T max is 4 to 12 h ( Asacol ). Approximately 21% to 22% is absorbed; C max is 857 to 2,154 ng/mL; AUC 0-∞ is 9,578 to 44,775 ng•h/mL; T max is 9 to 12 h ( Lialda ). Approximately 20% to 30% is absorbed; C max is 1.8 mcg/mL for N-acetylmesalamine metabolite; T max is approximately 3 h for N-acetylmesalamine ( Pentasa ). C max at steady state is 361 ng/mL; absorption is variable ( Canasa ). C max after 10 to 12 h is 2 mcg/mL, two thirds of which is the N-acetylmesalamine metabolite ( Rowasa ).


Approximately 43% bound to plasma proteins ( Lialda ).


Orally administered mesalamine products are rapidly acetylated in the gut mucosal wall and liver. Rectal dose forms are also acetylated, but the site of metabolism is unknown. The major metabolite is N-acetylmesalamine.


Unabsorbed mesalamine is excreted in feces; absorbed amount is excreted mainly in the kidney as N-acetyl-5-aminosalicylic acid. Mean t ½ is 2 to 15 h ( Asacol ). Excretion of absorbed dose was 8% as unchanged drug and greater than 113% as N-acetyl-5-aminosalicylic acid; the t ½ for mesalamine and N-acetyl-5-aminosalicylic acid was 7 to 9 h and 8 to 12 h, respectively ( Lialda ). Mean t ½ is 42 min (IV mesalamine) and 19% to 30% of N-acetyl-5-aminosalicylic acid was excreted in urine ( Pentasa ). At steady state, less than 11% of dose was eliminated in urine as unchanged drug and 3% to 35% was N-acetyl-5-aminosalicylic acid; mean t ½ at steady state was 7 h ( Canasa ). The t ½ of mesalamine is 0.5 to 1.5 h; the t ½ of N-acetyl-5-aminosalicylic acid is 5 to 10 h ( Rowasa ).

Indications and Usage

Treatment of mildly to moderately active ulcerative colitis ( Asacol , Pentasa ); induction of remission in patients with active, mild to moderate ulcerative colitis ( Lialda , Pentasa ); maintenance of remission of ulcerative colitis ( Asacol ); treatment of active ulcerative proctitis ( Canasa ); treatment of active mild to moderate distal ulcerative colitis, proctosigmoiditis, or proctitis ( Rowasa ).


Hypersensitivity to salicylates or any component of the product.

Dosage and Administration

Treatment of Active, Mild to Moderate Ulcerative Colitis

PO Asacol delayed-release tablets 800 mg 3 times daily (2.4 g/day) for 6 wk. Pentasa controlled-release capsules 1 g 4 times daily for up to 8 wk.

Maintenance of Remission of Ulcerative Colitis

PO Asacol delayed-release tablets 1.6 g daily, in divided doses.

Induction of Remission of Ulcerative Colitis

PO Lialda tablets 2.4 to 4.8 g once daily with a meal for up to 8 wk. Pentasa controlled-release capsules 1 g 4 times daily for up to 8 wk.

Treatment of Active Ulcerative Proctitis

PR Canasa rectal suppository 1,000 mg once daily at bedtime. Retain suppository in rectum for at least 1 to 3 h for max benefit. PR Rowasa rectal suspension enema 4 g in 60 mL as rectal instillation every day for up to 6 wk, preferably at bedtime, retained for 8 h.

Treatment of Active Mild to Moderate Distal Ulcerative Colitis or Proctosigmoiditis

PR Rowasa rectal suspension enema 4 g in 60 mL as rectal instillation every day for up to 6 wk, preferably at bedtime, retained for 8 h.

General Advice

  • Shake rectal suspension enema well to make sure suspension is homogeneous.
  • Rowasa rectal suspension enema can cause staining of direct contact surfaces, including fabrics, floor covering, painted surfaces, marble, granite, vinyl, and enamel.
  • Rowasa rectal suspension enema may darken with time. Slight darkening does not affect potency; however, discard enemas with dark brown contents.


Store at 68° to 77°F ( Asacol , Rowasa ).

Store at 77°F; keep away from direct heat, light, or humidity; do not freeze ( Canasa ).

Store at 59° to 86°F ( Lialda , Pentasa ).

Drug Interactions

Nephrotoxic agents (including NSAIDs)

Increased risk of renal adverse reactions.

Thiopurines (eg, azathioprine, mercaptopurine)

Risk of leukopenia may be increased.


Decreased anticoagulant effect of warfarin has been reported in 1 patient.

Adverse Reactions


Vasodilation (at least 2%); myocarditis, pericarditis (postmarketing).


Headache (35%); dizziness (8%); asthenia (7%); hypertonia (5%); fatigue, malaise, tiredness, weakness (4%); anxiety, migraine, nervousness, paresthesia (at least 2%); insomnia (2%); confusion, depression, emotional lability, Guillain-Barre syndrome, hyperesthesia, peripheral neuropathy, somnolence, transverse myelitis, tremor, vertigo (postmarketing).


Rash (6%); pruritus, sweating (3%); acne (2%); alopecia (1%); dry skin, erythema nodosum, psoriasis, pyoderma gangrenosum, urticaria (postmarketing).


Pharyngitis (11%); rhinitis (5%); ear disorder, ear pain, sinusitis, visual abnormalities (at least 2%); conjunctivitis (2%); blurred vision, eye pain, taste perversion, tinnitus (postmarketing).


Abdominal pain (18%); eructation (16%); nausea (13%); abdominal cramps/discomfort (8%); diarrhea (7%); dyspepsia, flatulence (6%); constipation, vomiting (5%); colitis exacerbation (3%); abdominal enlargement, gastroenteritis, GI hemorrhage, rectal disorder, rectal hemorrhage, stool abnormalities, tenesmus (at least 2%); bloating, rectal pain (2%); anorexia, hemorrhoids, melena (1%); bloody diarrhea, cholecystitis, dry mouth, gastritis, increased appetite, oral ulcers, pancreatitis, perforated peptic ulcer (postmarketing).


Dysmenorrhea (3%); urinary frequency (at least 2%); dysuria, epididymitis, hematuria, interstitial nephritis, menorrhagia, minimal change nephropathy, renal failure, urinary urgency (postmarketing).


Agranulocytosis, anemia, aplastic anemia, eosinophilia, granulocytopenia, leukopenia, lymphadenopathy, thrombocytopenia (postmarketing).


Cirrhosis, hepatocellular damage (including liver necrosis and live failure), hepatotoxicity (including cholestatic jaundice, hepatitis, and jaundice) (postmarketing).

Lab Tests

Elevated alkaline phosphatase, ALT, AST, bilirubin, BUN, gamma-glutamyltransferase, LDH, and serum creatinine (postmarketing).


Pain on insertion of enema tip, rectal pain with suppositories (1%).


Peripheral edema (3%); edema, facial edema (postmarketing).


Back pain (7%); arthralgia (5%); myalgia (3%); joint disorder (at least 2%); arthritis, joint pain, leg pain (2%); gout, neck pain (postmarketing).


Bronchitis (at least 2%); cold, increased cough, sore throat (2%); eosinophilic pneumonia, exacerbated asthma, interstitial pneumonitis, pleuritis (postmarketing).


Pain (14%); fever (6%); flu syndrome (5%); chest pain, chills (3%); infection (at least 2%); angioedema, drug fever, lupus-like syndrome, SLE (postmarketing).



Category B .


Excreted in breast milk ( Asacol , Lialda , Pentasa ). Undermined ( Canasa , Rowasa ).


Safety and efficacy not established.


Use with caution, usually starting at the low end of the dosage range, because of the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant diseases or other drug therapy.

Renal Function

Patients with history of renal function impairment or disease may have worsening of renal function.

Hepatic Function

Use with caution.

Sulfite Sensitivity

Some products may contain sulfites, which may cause allergic reactions in susceptible individuals.

Intolerance and colitis exacerbation

Some patients may develop acute intolerance syndrome or exacerbation of colitis characterized by cramping, acute abdominal pain, bloody diarrhea, and, occasionally, fever, headache, malaise, pruritus, conjunctivitis, and rash. Symptoms generally abate when mesalamine is discontinued.


Rarely, pericarditis has been reported. Observe for chest pain or dyspnea.

Pyloric stenosis

Gastric retention of oral mesalamine may occur in patients with pyloric stenosis.

Worsening symptoms

Worsening of colitis or symptoms of inflammatory bowel disease, including melena and hematochezia, may occur after starting mesalamine.



Products are salicylates; symptoms of salicylate toxicity may include confusion, dehydration, diarrhea, drowsiness, electrolyte and blood pH imbalance, headache, hyperthermia, hyperventilation, sweating, tinnitus, vertigo, vomiting.

Patient Information

  • Tell patient to swallow capsules or tablets whole. Explain that outer coating must be intact to pass through stomach and travel to sigmoid colon.
  • Tell patient to notify health care provider if any remnant of capsule or tablet is seen in stool.
  • Tell patient to retain suppository 1 to 3 h or to retain enema for 8 h.
  • Teach patient proper positioning and technique for self-administering enema. Include knee-chest and left side positions to promote medication advancement to sigmoid colon.
  • Tell patient to report the following symptoms to health care provider: increase in abdominal pain, diarrhea, or vomiting.
  • Instruct patient to notify health care provider of fever, hives, itching, rash, or wheezing.

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