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TOLBUTamide

Pronunciation

(tole BYOO ta mide)

Index Terms

  • Orinase
  • Tolbutamide Sodium

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Generic: 500 mg

Pharmacologic Category

  • Antidiabetic Agent, Sulfonylurea

Pharmacology

Stimulates insulin release from the pancreatic beta cells; reduces glucose output from the liver; insulin sensitivity is increased at peripheral target sites, suppression of glucagon may also contribute

Absorption

Oral: Rapid

Distribution

Vd: 0.15 L/kg

Metabolism

Hepatic via CYP2C9 to hydroxymethyltolbutamide (mildly active) and carboxytolbutamide (inactive); metabolism does not appear to be affected by age

Excretion

Urine (75% to 85% primarily as metabolites); feces

Onset of Action

1 hour

Time to Peak

Serum: 3-4 hours

Duration of Action

Oral: 6-24 hours

Half-Life Elimination

4.5-6.5 hours (range: 4-25 hours)

Protein Binding

~95% (concentration dependent)

Use: Labeled Indications

Adjunct to diet for the management of type 2 diabetes mellitus (noninsulin dependent, NIDDM)

Contraindications

Hypersensitivity to tolbutamide, sulfonylureas, or any component of the formulation; treatment of type 1 diabetes; diabetic ketoacidosis

Dosing: Adult

Type 2 diabetes: Oral: Initial: 1-2 g/day as a single dose in the morning or in divided doses throughout the day. Maintenance dose: 0.25-3 g/day; however, a maintenance dose >2 g/day is seldom required. Note: Divided doses may improve gastrointestinal tolerance

Dosing: Geriatric

Initial: 250 mg 1-3 times/day; usual: 500-2000 mg; maximum: 3 g/day

Dosing: Renal Impairment

No dosage adjustment provided in manufacturer’s labeling. However, conservative initial and maintenance doses are recommended.

Hemodialysis: Not dialyzable (0% to 5%)

Dosing: Hepatic Impairment

No dosage adjustment provided in manufacturer’s labeling. However, conservative initial and maintenance doses and careful monitoring of blood glucose are recommended.

Administration

Oral: Entire dose can be administered in AM, divided doses may improve GI tolerance.

Drug Interactions

Alcohol (Ethyl): Sulfonylureas may enhance the adverse/toxic effect of Alcohol (Ethyl). A flushing reaction may occur. Monitor therapy

Alpha-Lipoic Acid: May enhance the hypoglycemic effect of Antidiabetic Agents. Monitor therapy

Amodiaquine: CYP2C8 Inhibitors may increase the serum concentration of Amodiaquine. Avoid combination

Androgens: May enhance the hypoglycemic effect of Blood Glucose Lowering Agents. Exceptions: Danazol. Monitor therapy

Antidiabetic Agents: May enhance the hypoglycemic effect of Hypoglycemia-Associated Agents. Monitor therapy

Antidiabetic Agents (Thiazolidinedione): May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider sulfonylurea dose adjustments in patients taking thiazolidinediones and monitor for hypoglycemia. Consider therapy modification

Aprepitant: May decrease the serum concentration of TOLBUTamide. Monitor therapy

Beta-Blockers: May enhance the hypoglycemic effect of Sulfonylureas. Cardioselective beta-blockers (eg, acebutolol, atenolol, metoprolol, and penbutolol) may be safer than nonselective beta-blockers. All beta-blockers appear to mask tachycardia as an initial symptom of hypoglycemia. Ophthalmic beta-blockers are probably associated with lower risk than systemic agents. Exceptions: Levobunolol; Metipranolol. Monitor therapy

Bosentan: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Bosentan. Management: Concomitant use of both a CYP2C9 inhibitor and a CYP3A inhibitor or a single agent that inhibits both enzymes with bosentan is likely to cause a large increase in serum concentrations of bosentan and is not recommended. See monograph for details. Monitor therapy

Cannabis: May increase the serum concentration of CYP2C9 Inhibitors (Strong). More specifically, tetrahydrocannabinol serum concentrations may be increased. Monitor therapy

Carbocisteine: Sulfonylureas may enhance the adverse/toxic effect of Carbocisteine. Specifically, sulfonylureas may enhance adverse effects of alcohol that is present in liquid formulations of carbocisteine-containing products. Monitor therapy

Carvedilol: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Carvedilol. Specifically, concentrations of the S-carvedilol enantiomer may be increased. Monitor therapy

Ceritinib: May increase the serum concentration of CYP2C9 Substrates. Management: Concurrent use of ceritinib with a CYP2C9 substrate that has a narrow therapeutic index (e.g., warfarin, phenytoin) should be avoided when possible. Monitor therapy

Chloramphenicol: May decrease the metabolism of Sulfonylureas. Monitor therapy

Cimetidine: May increase the serum concentration of Sulfonylureas. Monitor therapy

Cyclic Antidepressants: May enhance the hypoglycemic effect of Sulfonylureas. Monitor therapy

CYP2C9 Inducers (Strong): May increase the metabolism of CYP2C9 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

CYP2C9 Inhibitors (Moderate): May decrease the metabolism of CYP2C9 Substrates. Monitor therapy

CYP2C9 Inhibitors (Strong): May decrease the metabolism of CYP2C9 Substrates. Consider therapy modification

CYP2C9 Substrates: CYP2C9 Inhibitors (Strong) may decrease the metabolism of CYP2C9 Substrates. Consider therapy modification

Dabrafenib: May decrease the serum concentration of CYP2C9 Substrates. Management: Seek alternatives to the CYP2C9 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects). Consider therapy modification

Dexketoprofen: May enhance the adverse/toxic effect of Sulfonamides. Monitor therapy

Diclofenac (Systemic): CYP2C9 Inhibitors (Strong) may increase the serum concentration of Diclofenac (Systemic). Management: Consider using a lower dose of diclofenac when used together with a strong CYP2C9 inhibitor. Arthrotec (diclofenac and misoprostol) labeling specifically recommends limiting the total daily dose to a maximum of 50 mg twice/day. Consider therapy modification

DPP-IV Inhibitors: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider a decrease in sulfonylurea dose when initiating therapy with a dipeptidyl peptidase-IV inhibitor and monitor patients for hypoglycemia. Consider therapy modification

Dronabinol: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Dronabinol. Monitor therapy

Enzalutamide: May decrease the serum concentration of CYP2C9 Substrates. Management: Concurrent use of enzalutamide with CYP2C9 substrates that have a narrow therapeutic index should be avoided. Use of enzalutamide and any other CYP2C9 substrate should be performed with caution and close monitoring. Consider therapy modification

Fibric Acid Derivatives: May enhance the hypoglycemic effect of Sulfonylureas. Monitor therapy

Fluconazole: May increase the serum concentration of Sulfonylureas. Management: Seek alternatives when possible. If used together, monitor closely for increased effects of sulfonylureas if fluconazole is initiated/dose increased, or decreased effects if fluconazole is discontinued/dose decreased. Consider therapy modification

Fosaprepitant: May decrease the serum concentration of TOLBUTamide. Monitor therapy

GLP-1 Agonists: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider sulfonylurea dose reductions when used in combination with glucagon-like peptide-1 agonists. Avoid the use of lixisenatide in patients receiving both basal insulin and a sulfonylurea. Consider therapy modification

Herbs (Hypoglycemic Properties): May enhance the hypoglycemic effect of Hypoglycemia-Associated Agents. Monitor therapy

Hyperglycemia-Associated Agents: May diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Hypoglycemia-Associated Agents: May enhance the hypoglycemic effect of other Hypoglycemia-Associated Agents. Monitor therapy

Hypoglycemia-Associated Agents: Antidiabetic Agents may enhance the hypoglycemic effect of Hypoglycemia-Associated Agents. Monitor therapy

Lacosamide: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Lacosamide. Monitor therapy

Leflunomide: May increase the serum concentration of TOLBUTamide. Specifically, the active metabolite of leflunomide (teriflunomide) may both increase total tolbutamide concentrations and increase the free fraction (i.e., non-protein bound) of tolbutamide. TOLBUTamide may increase the serum concentration of Leflunomide. Specifically, tolbutamide may increase the proportion of non-protein-bound (i.e., free fraction) teriflunomide. Monitor therapy

Lumacaftor: May decrease the serum concentration of CYP2C9 Substrates. Lumacaftor may increase the serum concentration of CYP2C9 Substrates. Monitor therapy

MAO Inhibitors: May enhance the hypoglycemic effect of Blood Glucose Lowering Agents. Monitor therapy

Mecamylamine: Sulfonamides may enhance the adverse/toxic effect of Mecamylamine. Avoid combination

Metreleptin: May enhance the hypoglycemic effect of Sulfonylureas. Management: Sulfonylurea dosage adjustments (including potentially large decreases) may be required to minimize the risk for hypoglycemia with concurrent use of metreleptin. Monitor closely. Consider therapy modification

Miconazole (Oral): May enhance the hypoglycemic effect of Sulfonylureas. Miconazole (Oral) may increase the serum concentration of Sulfonylureas. Monitor therapy

Mifepristone: May increase the serum concentration of CYP2C9 Substrates. Management: Use CYP2C9 substrates at the lowest recommended dose, and monitor closely for adverse effects, during and in the 2 weeks following mifepristone treatment. Consider therapy modification

Ospemifene: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Ospemifene. Monitor therapy

Parecoxib: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Parecoxib. Monitor therapy

Pegvisomant: May enhance the hypoglycemic effect of Blood Glucose Lowering Agents. Monitor therapy

Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Monitor therapy

Probenecid: May decrease the protein binding of Sulfonylureas. Probenecid may increase the serum concentration of Sulfonylureas. Monitor therapy

Quinolone Antibiotics: May enhance the hypoglycemic effect of Blood Glucose Lowering Agents. Quinolone Antibiotics may diminish the therapeutic effect of Blood Glucose Lowering Agents. Specifically, if an agent is being used to treat diabetes, loss of blood sugar control may occur with quinolone use. Monitor therapy

Ramelteon: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Ramelteon. Monitor therapy

Ranitidine: May increase the serum concentration of Sulfonylureas. Monitor therapy

Rifampin: May decrease the serum concentration of Sulfonylureas. Management: Seek alternatives to these combinations when possible. Monitor closely for diminished therapeutic effects of sulfonylureas if rifampin is initiated/dose increased, or enhanced effects if rifampin is discontinued/dose decreased. Consider therapy modification

Salicylates: May enhance the hypoglycemic effect of Blood Glucose Lowering Agents. Monitor therapy

Selective Serotonin Reuptake Inhibitors: May enhance the hypoglycemic effect of Blood Glucose Lowering Agents. Monitor therapy

SGLT2 Inhibitors: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider a decrease in sulfonylurea dose when initiating therapy with a sodium-glucose cotransporter 2 inhibitor and monitor patients for hypoglycemia. Consider therapy modification

Sulfonamide Derivatives: May enhance the hypoglycemic effect of Sulfonylureas. Monitor therapy

Tetrahydrocannabinol: CYP2C9 Inhibitors (Strong) may increase the serum concentration of Tetrahydrocannabinol. Monitor therapy

Thiazide and Thiazide-Like Diuretics: May diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Verteporfin: Photosensitizing Agents may enhance the photosensitizing effect of Verteporfin. Monitor therapy

Adverse Reactions

Frequency not defined.

Central nervous system: Headache

Dermatologic: Erythema, maculopapular rash, morbilliform rash, pruritus, urticaria, photosensitivity

Endocrine & metabolic: Disulfiram-like reactions, hypoglycemia, hyponatremia, SIADH

Gastrointestinal: Epigastric fullness, heartburn, nausea, taste alteration

Hematologic: Agranulocytosis, aplastic anemia, hemolytic anemia, leukopenia, pancytopenia, thrombocytopenia

Hepatic: Cholestatic jaundice, hepatic porphyria, porphyria cutanea tarda

Miscellaneous: Hypersensitivity reaction

Warnings/Precautions

Concerns related to adverse reactions:

• Cardiovascular mortality: Product labeling states oral hypoglycemic drugs may be associated with an increased cardiovascular mortality as compared to treatment with diet alone or diet plus insulin. Data to support this association are limited, and several studies, including a large prospective trial (UKPDS) have not supported an association.

• Hypoglycemia: All sulfonylurea drugs are capable of producing severe hypoglycemia. Hypoglycemia is more likely to occur when caloric intake is deficient, after severe or prolonged exercise, when ethanol is ingested, or when more than one glucose-lowering drug is used. It is also more likely in elderly patients, malnourished patients and in patients with impaired renal or hepatic function; use with caution.

• Sulfonamide (“sulfa”) allergy: The FDA-approved product labeling for many medications containing a sulfonamide chemical group includes a broad contraindication in patients with a prior allergic reaction to sulfonamides. There is a potential for cross-reactivity between members of a specific class (eg, two antibiotic sulfonamides). However, concerns for cross-reactivity have previously extended to all compounds containing the sulfonamide structure (SO2NH2). An expanded understanding of allergic mechanisms indicates cross-reactivity between antibiotic sulfonamides and nonantibiotic sulfonamides may not occur or at the very least this potential is extremely low (Brackett 2004; Johnson 2005; Slatore 2004; Tornero 2004). In particular, mechanisms of cross-reaction due to antibody production (anaphylaxis) are unlikely to occur with nonantibiotic sulfonamides. T-cell-mediated (type IV) reactions (eg, maculopapular rash) are less well understood and it is not possible to completely exclude this potential based on current insights. In cases where prior reactions were severe (Stevens-Johnson syndrome/TEN), some clinicians choose to avoid exposure to these classes.

Disease-related concerns:

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency: Patients with G6PD deficiency may be at an increased risk of sulfonylurea-induced hemolytic anemia; however, cases have also been described in patients without G6PD deficiency during postmarketing surveillance. Use with caution and consider a nonsulfonylurea alternative in patients with G6PD deficiency.

• Stress-related states: It may be necessary to discontinue therapy and administer insulin if the patient is exposed to stress (fever, trauma, infection, surgery).

Other warnings/precautions:

• Secondary failure: Loss of efficacy may be observed following prolonged use as a result of the progression of type 2 diabetes mellitus which results in continued beta cell destruction. In patients who were previously responding to sulfonylurea therapy, consider additional factors which may be contributing to decreased efficacy (eg, inappropriate dose, nonadherence to diet and exercise regimen). If no contributing factors can be identified, consider discontinuing use of the sulfonylurea due to secondary failure of treatment. Additional antidiabetic therapy (eg, insulin) will be required.

Monitoring Parameters

Blood glucose, hemoglobin A1c (at least twice yearly in patients who have stable glycemic control and are meeting treatment goals; quarterly in patients not meeting treatment goals or with therapy change [ADA 2016a]); signs and symptoms of hypoglycemia

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events have been observed in animal reproduction studies. Tolbutamide crosses the placenta and can be measured in the serum of newborn infants following maternal use during pregnancy (Miller 1962). Severe hypoglycemia lasting 4 to 10 days has been noted in infants born to mothers taking a sulfonylurea at the time of delivery. Additional adverse events have been reported and may be influenced by maternal glycemic control (Larsson 1960; Saili 1991; Schiff 1970).

In women with diabetes, maternal hyperglycemia can be associated with congenital malformations as well as adverse effects in the fetus, neonate, and the mother (ACOG 2005; ADA 2015; Kitzmiller 2008; Metzger 2007). To prevent adverse outcomes, prior to conception and throughout pregnancy maternal blood glucose and HbA1c should be kept as close to target goals as possible but without causing significant hypoglycemia (ACOG 2013; ADA 2015; Blumer 2013; Kitzmiller 2008). Prior to pregnancy, effective contraception should be used until glycemic control is achieved (Kitzmiller 2008). Other agents are currently recommended to treat diabetes in pregnant women (ACOG 2013; Blumer 2013).

The manufacturer recommends if tolbutamide is used during pregnancy, it should be discontinued at least 2 weeks before the expected delivery date.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience dyspepsia, pyrosis, or bloating. Have patient report immediately to prescriber illogical thinking, severe dizziness, syncope, ecchymosis, hemorrhaging, considerable asthenia, urine discoloration, jaundice, chills, pharyngitis, or hypoglycemia (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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