Balsalazide Disodium Tablets
TABLE OF CONTENTS
Balsalazide disodium is an orally available prodrug that is enzymatically cleaved to produce mesalamine (5-aminosalicylic acid, 5-ASA), an anti-inflammatory drug. Balsalazide disodium has the chemical name (E)-5-[[-4-[[(2-carboxyethyl) amino]carbonyl] phenyl]azo]-2-hydroxybenzoic acid, disodium salt, dihydrate. Its structural formula is:
Empirical formula: C17H13N3O6Na2•2H2O - Molecular weight: 437.32
Balsalazide disodium is a stable, odorless, orange to yellow, microcrystalline powder. It is insoluble in acid, but soluble at a pH of at least 4.5. It is freely soluble in water and isotonic saline, sparingly soluble in methanol and ethanol, and practically insoluble in all other organic solvents.
Inactive Ingredients: Each tablet contains hypromellose, magnesium stearate, and Opadry II Yellow. The sodium content of each tablet is approximately 126 mg.
|2. INDICATIONS AND USAGE|
Balsalazide is indicated for the treatment of mildly to moderately active ulcerative colitis in male patients 18 years of age and older.
Limitations of Use:
• Effectiveness of balsalazide in the treatment of female patients was not demonstrated in clinical trials.
• Safety and effectiveness of balsalazide therapy beyond 8 weeks have not been established.
|3. DOSAGE AND ADMINISTRATION|
The dose is three 1.1 g balsalazide tablets to be taken 2 times a day with or without food (6.6 g per day) for up to 8 weeks.
Balsalazide is contraindicated in patients with hypersensitivity to salicylates, aminosalicylates or their metabolites, or to any of the components of balsalazide tablets [see Description].
|5. MECHANISM OF ACTION|
Balsalazide is a prodrug of mesalamine (5-aminosalicylic acid, 5-ASA). The mechanism of action of 5-ASA is unknown, but appears to be local to the colonic mucosa rather than systemic. Mucosal production of arachidonic acid metabolites, both through the cyclooxygenase pathways, i.e., prostanoids, and through the lipoxygenase pathways, i.e., leukotrienes and hydroxyeicosatetraenoic acids, is increased in patients with ulcerative colitis, and it is possible that 5-ASA diminishes inflammation by blocking production of arachidonic acid metabolites in the colon.
|6. USE IN SPECIFIC POPULATIONS|
6.1 Usage in Pregnancy
Pregnancy Category B
Reproduction studies were performed in rats and rabbits at oral doses up to 2 g/kg/day, 2.5 and 4.9 times the recommended human dose based on body surface area for the rat and rabbit, respectively, and revealed no evidence of impaired fertility or harm to the fetus due to balsalazide disodium. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
Mesalamine, a metabolite of balsalazide, is known to cross the placental barrier.
6.2 Nursing Mothers
It is not known whether balsalazide disodium or its metabolites are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when balsalazide is administered to a nursing woman.
6.3 Pediatric Use
Safety and effectiveness of balsalazide in pediatric patients have not been established.
6.5 Geriatric Use
Reports from uncontrolled clinical studies and postmarketing reporting systems suggested a higher incidence of blood dyscrasias, i.e., neutropenia and pancytopenia, in patients who were 65 years or older who were taking mesalamine-containing products. Balsalazide is converted into mesalamine in the colon. Caution should be taken to closely monitor blood cell counts during therapy.
Clinical trials of balsalazide did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently than younger subjects. Other reported clinical experience has not identified differences in responses between elderly and younger patients. In general, the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy in elderly patients should be considered when prescribing balsalazide.
|7. WARNINGS AND PRECAUTIONS|
7.1 Exacerbations of Ulcerative Colitis
Balsalazide is converted to mesalamine, which has been associated with an acute intolerance syndrome that may be difficult to distinguish from an exacerbation of ulcerative colitis. In controlled clinical trials with balsalazide in adults with ulcerative colitis, 7% of male patients reported exacerbation of the symptoms of ulcerative colitis. Symptoms include cramping, acute abdominal pain and bloody diarrhea, sometimes fever, headache, and rash. Observe patients closely for worsening of these symptoms while on treatment. If acute intolerance syndrome is suspected, promptly discontinue treatment with balsalazide.
7.2 Renal Impairment
Renal impairment, including minimal change nephropathy, acute and chronic interstitial nephritis and renal failure, has been reported in patients given products that release mesalamine in the gastrointestinal tract. Evaluate renal function prior to initiation of balsalazide therapy and periodically while on therapy. Exercise caution when using balsalazide in patients with known renal dysfunction or a history of renal disease.
7.3 Use in Hepatic Impairment
There have been reports of hepatic failure in patients with pre-existing liver disease who have been administered mesalamine. Because balsalazide is converted to mesalamine, use caution and consider liver function testing when administering balsalazide to patients with liver disease.
|8. ADVERSE REACTIONS|
8.1 Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
The data described below reflect exposure of balsalazide in 565 ulcerative colitis patients with mildly to moderately active disease. Balsalazide was evaluated in one placebo-controlled trial (168 treated with balsalazide), one active-controlled trial (210 treated with balsalazide); and a subset of these patients also participated in an uncontrolled, open-label, extension study (additional 187 treated with balsalazide). The population studied had a mean age of 43.1 (range: 18-80) years; approximately 94% of patients were < 65 years old, 49% were male, and 84% were white.
In the placebo-controlled trial, the most common adverse reactions with balsalazide in male patients were headache, nasopharyngitis, anemia, diarrhea, fatigue, pharyngolaryngeal pain, and urinary tract infection. 10% of patients in the balsalazide group and 13% of patients in the placebo group discontinued treatment due to an adverse reaction. The majority of adverse reactions were mild to moderate in severity. The most common serious adverse reactions in both the placebo and balsalazide groups were gastrointestinal disorders, which were mainly associated with symptoms of ulcerative colitis.
Adverse reactions occurring in at least 2% of male patients and at a rate numerically higher than placebo in the placebo-controlled trial are listed in Table 1.
Table 1: Adverse Reactions Experienced by at Least 2% of Balsalazide - Treated Male Patients and at a Rate Numerically Greater than Placebo in a Placebo-Controlled Trial
Data collected from all three trials (placebo-controlled, active-controlled, and open-label) showed that female patients reported adverse reactions more frequently than did male patients (76% and 66%, respectively).
The following adverse reactions, presented by body system, were reported by less than 1% of balsalazide-treated ulcerative colitis patients in controlled trials.
Cardiovascular and Vascular: increased blood pressure, increased heart rate
Dermatological: erythema nodosum, rash
Respiratory, Thoracic and Mediastinal Disorders: dyspnea
Gastrointestinal Disorders: abdominal pain, constipation, defecation urgency, diarrhea, dry mouth, hard feces, flatulence, gastroesophageal reflux disease, vomiting
Hepatobiliary Disorders: increased aspartate aminotransferase
Infections and Infestations: gastroenteritis, upper respiratory infection
Musculoskeletal and Connective Tissue Disorders: arthralgia, back pain, myalgia
Nervous System Disorders: dizziness, lethargy
General Disorders and Administrative Site Disorders: face edema, fatigue, malaise, pain, pyrexia, swelling
8.2 Postmarketing Experience
Because these reactions are reported voluntarily from a population of unknown size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. These adverse reactions have been chosen for inclusion due to a combination of seriousness, frequency of reporting, or potential causal connection to products which contain or are metabolized to mesalamine, including balsalazide.
Cardiovascular and Vascular: myocarditis, pericarditis, vasculitis
Respiratory: alveolitis, pleural effusion, pneumonia (with and without eosinophilia)
Renal: interstitial nephritis, renal failure.
Hepatobiliary Disorders: elevated liver enzymes (AST, ALT, GGT, LDH, alkaline phosphatase), elevated bilirubin, jaundice, cholestatic jaundice, cirrhosis, hepatocellular damage including liver necrosis and liver failure, Kawasaki-like syndrome including hepatic dysfunction. Some of these cases were fatal.
Dermatological: alopecia, pruritus
No case of overdose has been reported with balsalazide. Balsalazide is an aminosalicylate, and symptoms of salicylate toxicity include: hematemesis, tachypnea, hyperpnea, tinnitus, deafness, lethargy, seizures, confusion, or dyspnea. Severe intoxication may lead to electrolyte and blood pH imbalance and potentially to other organ (e.g., renal and liver) involvement. There is no specific antidote for balsalazide overdose. Proper medical care should be sought immediately with appropriate supportive care, including the possible use of emesis, cathartics, and activated charcoal to prevent further absorption.
|10. DRUG INTERACTIONS|
Based on in vitro studies, balsalazide and its metabolites [5-aminosalicylic acid (5-ASA), N-acetyl-5-aminosalicylic acid (N-Ac-5-ASA), 4-aminobenzoyl-β-alanine (4-ABA), and N-acetyl-4-aminobenzoyl-β-alanine (N-Ac-4-ABA)] are not expected to inhibit the metabolism of other drugs that are substrates of CYP1A2, CYP2C9, CYP2C19, CYP2D6, or CYP3A4/5.
Following oral administration, balsalazide is cleaved by azoreductases produced by anaerobic bacteria found in the gut, to release equimolar quantities of 5-ASA, the active moiety, and 4-aminobenzoyl-β-alanine (4-ABA), a carrier moiety. Both of these moieties are N-acetylated to form N-Ac-5-ASA and N-Ac-4-ABA, respectively.
After single-dose administration of 3.3 g balsalazide in 18 healthy subjects, the median time of peak plasma concentration (Tmax) was 0.5 hr for balsalazide, while the median Tmax was 12 hr for both 5-ASA and N-Ac-5-ASA (Table 2). Pharmacokinetic parameters exhibited high variability, with %CV ranging from 31% to 67% for AUC and from 27% to 68% for Cmax.
Pharmacokinetics were also estimated in healthy volunteers after repeated doses of 3.3 g balsalazide tablets every 12 hours for 7 days. After multiple doses, steady-state was achieved after about 3 days for balsalazide and all metabolites. The AUC and Cmax were the highest for N-Ac-5-ASA, followed by 5-ASA and balsalazide. There was minimal accumulation of balsalazide, as suggested by a 1.2-fold increase in AUC; however, a relatively larger increase in the systemic exposure to metabolites was observed at steady-state. The accumulation ratios based on AUC for the metabolites were 6.1 for 5-ASA, 3.6 for N-Ac-5-ASA, 4.8 for 4-ABA, and 3.6 for N-Ac-4-ABA.
Table 2: Pharmacokinetic Parameters for Balsalazide and Metabolites (5-ASA and N-Ac-5-ASA) Following Single-and Repeated-Doses (Q12) of 3.3 g Balsalazide Disodium as Balsalazide (N=18)
a Expressed as median and range.
After administration of single dose of 3.3 g (3 x 1.1 g tablets) of balsalazide with a high-fat meal in healthy volunteers, the AUC of balsalazide was unaffected compared to fasted administration, but the presence of food reduced both peak concentrations and AUC of the metabolites 5-ASA and N-Ac-5-ASA. A high fat meal increased the median Tmax for balsalazide from 0.5 to 2 hours; for 5-ASA from 12 to 24 hours; and for N-Ac-5-ASA from 12 to 24 hours. Under fed conditions, the mean Cmax was reduced by 44% for balsalazide, 65% for 5-ASA, and 48% for N-Ac-5-ASA. No significant changes were observed for AUC0-∞for balsalazide; however, AUC0-∞ was reduced for 5-ASA by 46% and for N-Ac-5-ASA by 17%.
The binding of balsalazide to human plasma proteins was ≥ 99%; 5-ASA and N-Ac-5-ASA were 43% and 78% bound, respectively, to plasma proteins.
Metabolism and Excretion
Following oral administration, balsalazide is cleaved by bacterial azoreduction to release equimolar quantities of 5-ASA, the active moiety, and 4-ABA, a carrier moiety. Mesalamine (5-ASA) and 4-ABA are further acetylated to N-Ac-5-ASA and N-Ac-4-ABA, respectively in the intestinal mucosa and liver. The terminal half-life was 1.9 h for balsalazide, 9.5 h for 5-ASA, and 10.5 h for N-Ac-5-ASA.
At steady-state following administration of repeated doses of 3.3 g balsalazide every 12 hours in healthy volunteers, the combined % of dose excreted in urine for balsalazide and its metabolites over 12 hours was 23%. The mean % of dose excreted in urine over 12 hours was 0.16% for balsalazide, 4.6% for 5-ASA, 15.6% for N-Ac-5-ASA, 0.40% for 4-ABA, and 1.8% for N-Ac-4-ABA.
|12. HOW SUPPLIED/STORAGE AND HANDLING|
1) How Available:
a) Brand name: GIAZO, by Salix Pharmaceuticals.
b) Generic drugs: None.
2) How Supplied:
GIAZO is available as oval, yellow, film-coated tablets containing 1.1 g balsalazide disodium, with BZT debossed on one side of the tablet.
NDC 65649-102-02 Bottles of 180 tablets
NDC 65649-102-03 Bottles of 500 tablets
3) Storage and Handling:
Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° and 30°C (59° and 86°F). [see USP Controlled Room Temperature].