ADVERSE REACTIONS SECTION.

6 ADVERSE REACTIONS. The following clinically significant adverse reactions are described elsewhere in the labeling: Hypotension [see Warnings and Precautions (5.1)] Bradycardia [see Warnings and Precautions (5.2)] Depression of myocardial contractility in patients with overt congestive heart failure [see Warnings and Precautions (5.3)] Aggravation of angina [see Warnings and Precautions (5.4)] Significant decline in cardiac output following coronary bypass [see Warnings and Precautions (5.3)] Bronchospasm in patients with reactive airway disease [see Warnings and Precautions (5.5)] Paradoxical hypertensive responses in patients with pheochromocytoma [see Warnings and Precautions (5.7)] Hepatic injury [see Warnings and Precautions (5.8)] Acute hypersensitivity reaction [see Warnings and Precautions (5.9)] Hypotension [see Warnings and Precautions (5.1)] Bradycardia [see Warnings and Precautions (5.2)] Depression of myocardial contractility in patients with overt congestive heart failure [see Warnings and Precautions (5.3)] Aggravation of angina [see Warnings and Precautions (5.4)] Significant decline in cardiac output following coronary bypass [see Warnings and Precautions (5.3)] Bronchospasm in patients with reactive airway disease [see Warnings and Precautions (5.5)] Paradoxical hypertensive responses in patients with pheochromocytoma [see Warnings and Precautions (5.7)] Hepatic injury [see Warnings and Precautions (5.8)] Acute hypersensitivity reaction [see Warnings and Precautions (5.9)] Most common adverse events:Symptomatic postural hypotension. (6)Nausea13%, dizziness 9% (6)To report SUSPECTED ADVERSE REACTIONS, contact Hikma Pharmaceuticals USA Inc. at 1-877-845-0689, or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. For product Inquiry call 1-877-845-0689.. Symptomatic postural hypotension. (6). Nausea13%, dizziness 9% (6). 6.1 Clinical Trial Experience. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.Most adverse effects have been mild and transient and, in controlled trials involving 92 patients, did not require labetalol withdrawal. Symptomatic postural hypotension (incidence, 58%) is likely to occur if patients are tilted or allowed to assume the upright position within hours of receiving labetalol HCl. Moderate hypotension occurred in of 100 patients while supine. Increased sweating was noted in of 100 patients, and flushing occurred in of 100 patients.The following also were reported with labetalol HCl with the incidence as noted:Central and Peripheral Nervous SystemsDizziness in 9%Paresthesia, most frequently described as tingling of the scalp/skin in 7%Gastrointestinal SystemNausea in 13%Vomiting in 4%Metabolic DisordersTransient increases in blood urea nitrogen and serum creatinine levels occurred in 8%; these were associated with drops in blood pressure, generally in patients with prior renal insufficiency.Respiratory SystemBronchospasmIn addition, number of other less common adverse events have been reported:Cardiovascular:Hypotension, and rarely, syncope, bradycardia, heart block.Liver and Biliary SystemHepatic necrosis, hepatitis, cholestatic jaundice, elevated liver function tests.HypersensitivityRare reports of hypersensitivity (e.g., rash, urticaria, pruritus, angioedema, dyspnea) and anaphylactoid reactions.The oculomucocutaneous syndrome associated with the beta blocker practolol has not been reported with labetalol HCl during investigational use and extensive foreign marketing experience.Clinical Laboratory TestsAmong patients dosed with labetalol tablets, there have been reversible increases of serum transaminases in 4% of patients tested and, more rarely, reversible increases in blood urea.

PHARMACODYNAMICS SECTION.

12.2 Pharmacodynamics. In clinical pharmacologic study in severe hypertensives, an initial 0.25 mg/kg injection of labetalol HCl administered to patients in the supine position decreased blood pressure by an average of 11/7 mmHg. Additional injections of 0.5 mg/kg at 15-minute intervals up to total cumulative dose of 1.75 mg/kg of labetalol HCl caused further dose-related decreases in blood pressure. Some patients required cumulative doses of up to 3.25 mg/kg. The maximal effect of each dose level occurred within minutes. Following discontinuation of intravenous treatment with labetalol HCl, the blood pressure rose gradually and progressively, approaching pretreatment baseline values within an average of 16 to 18 hours in the majority of patients.Similar results were obtained in the treatment of patients with severe hypertension who required urgent blood pressure reduction with an initial dose of 20 mg (which corresponds to 0.25 mg/kg for an 80 kg patient) followed by additional doses of either 40 or 80 mg at 10 minute intervals to achieve the desired effect, or up to cumulative dose of 300 mg.Labetalol HCl administered as continuous intravenous infusion, with mean dose of 136 mg (27 to 300 mg) over period of to hours (mean of hours and 39 minutes), lowered the blood pressure by an average of 60/35 mmHg.

CLINICAL PHARMACOLOGY SECTION.

12 CLINICAL PHARMACOLOGY. 12.1 Mechanism of Action. Labetalol has both competitive alpha1-adrenergic blocking and competitive beta-adrenergic blocking activity. In man, the ratio of alpha- to beta-blockade has been estimated to be approximately 1:7 following intravenous administration. Beta2-agonist activity has been demonstrated in animals with minimal beta1-agonist (ISA) activity detected. In animals, at doses greater than those required for alpha- or beta-adrenergic blockade, membrane stabilizing effect has been demonstrated.. 12.2 Pharmacodynamics. In clinical pharmacologic study in severe hypertensives, an initial 0.25 mg/kg injection of labetalol HCl administered to patients in the supine position decreased blood pressure by an average of 11/7 mmHg. Additional injections of 0.5 mg/kg at 15-minute intervals up to total cumulative dose of 1.75 mg/kg of labetalol HCl caused further dose-related decreases in blood pressure. Some patients required cumulative doses of up to 3.25 mg/kg. The maximal effect of each dose level occurred within minutes. Following discontinuation of intravenous treatment with labetalol HCl, the blood pressure rose gradually and progressively, approaching pretreatment baseline values within an average of 16 to 18 hours in the majority of patients.Similar results were obtained in the treatment of patients with severe hypertension who required urgent blood pressure reduction with an initial dose of 20 mg (which corresponds to 0.25 mg/kg for an 80 kg patient) followed by additional doses of either 40 or 80 mg at 10 minute intervals to achieve the desired effect, or up to cumulative dose of 300 mg.Labetalol HCl administered as continuous intravenous infusion, with mean dose of 136 mg (27 to 300 mg) over period of to hours (mean of hours and 39 minutes), lowered the blood pressure by an average of 60/35 mmHg.. 12.3 Pharmacokinetics. DistributionLabetalol has been shown to cross the placental barrier in humans. Only negligible amounts of the drug crossed the blood-brain barrier in animal studies. Labetalol is approximately 50% protein bound. Neither hemodialysis nor peritoneal dialysis removes significant amount of labetalol from the systemic circulation (<1%).EliminationFollowing intravenous infusion of labetalol, the elimination half-life is about 5.5 hours and the total body clearance is approximately 33 mL/min/kg. Steady-state plasma levels of labetalol during repetitive dosing are reached following 22 to 28 hours of continuous infusion.MetabolismThe metabolism of labetalol is mainly through conjugation to glucuronide metabolites. ExcretionApproximately 55% to 60% of dose appears in the urine as conjugates or unchanged labetalol within the first 24 hours of dosing. The metabolites are present in plasma and are excreted in the urine and, via the bile, into the feces.Specific Populations Patients with Renal or Hepatic Impairment In patients with decreased hepatic or renal function, the elimination half-life of labetalol is not altered. Geriatric PatientsSome pharmacokinetic studies indicate that the elimination of labetalol is reduced in elderly patients.

DESCRIPTION SECTION.

11 DESCRIPTION. Labetalol HCl in Sodium Chloride Injection and Labetalol HCl in Dextrose Injection contain labetalol HCl an adrenergic receptor blocking agent that has both selective alpha1-adrenergic and nonselective beta-adrenergic receptor blocking actions in single substance. Labetalol hydrochloride (HCl) is racemate chemically designated as 5-[1-Hydroxy-2-[(1-methyl-3-phenylpropyl)amino]ethyl]-salicylamide monohydrochloride and it has the following structural formula: Labetalol HCl is white or off-white crystalline powder, soluble in water. Labetalol HCl has the molecular formula C19H24N2O3oHCl and molecular weight of 364.87. It has two asymmetric centers and therefore exists as molecular complex of two diastereoisomeric pairs. Labetalol HCl in Sodium Chloride Injection and Labetalol HCl in Dextrose Injection are two preservative-free, ready-to use formulations of labetalol. Labetalol HCl in Sodium Chloride Injection and Labetalol HCl in Dextrose Injection are clear, colorless to light yellow, aqueous, sterile, isotonic solution for intravenous injection. Each milliliter of Labetalol HCl in Sodium Chloride Injection contains mg of labetalol HCl, 7.2 mg sodium chloride, mg of anhydrous dextrose, 0.02 mg of edetate disodium; and citric acid monohydrate and sodium hydroxide, as necessary, to bring the solution into the pH range of 3.5 to 4.5. Each milliliter of Labetalol HCl in Dextrose Injection contains mg of labetalol HCl, 45 mg of anhydrous dextrose, 0.02 mg of edetate disodium; and citric acid monohydrate and sodium hydroxide, as necessary, to bring the solution into the pH range of 3.5 to 4.5.. structural formula.

DOSAGE & ADMINISTRATION SECTION.

2 DOSAGE AND ADMINISTRATION. Administered as slow continuous infusion at rate of mL/min to deliver mg/min. (2.1). 2.1 General Information. Labetalol HCl in Sodium Chloride Injection and Labetalol HCl in Dextrose Injection are ready-to-use solutions and do not require further dilution. Check for leaks by squeezing the bag firmly. If leaks are found, discard solution, as sterility may be impaired. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Do not use the content of the bag unless the solution is clear (colorless to light yellow) and the seal is intact. Do not add any additional medications to the bag.Once infusion has started, discard any remaining at 24 hours. 2.2 Recommended Dosage. The recommended initial dosage is mg/minute by continuous intravenous infusion, which is mL/minute. Monitor blood pressure and adjust the dosage and duration of infusion accordingly.Once supine diastolic blood pressure has begun to rise, transition to oral labetalol HCl. The usual intravenous dose is in the range of 50 to 200 mg. total dose of up to 300 mg may be required in some patients, but the safety of doses above 300 mg has not been established.

DRUG INTERACTIONS SECTION.

7 DRUG INTERACTIONS. Beta blockers antagonize the bronchodilator effect of beta-receptor agonists. (7.1)Increase hypotension may occur with halothane anesthesia. (7.2)Nitroglycerin may result in additional hypotensive effects. (7.3). Beta blockers antagonize the bronchodilator effect of beta-receptor agonists. (7.1). Increase hypotension may occur with halothane anesthesia. (7.2). Nitroglycerin may result in additional hypotensive effects. (7.3). 7.1 Bronchodilators. Labetalol HCl antagonizes the bronchodilatory effect of beta-receptor agonist drugs; therefore, labetalol HCl is contraindicated in patients with bronchial asthma [see Contraindications (4)].. 7.2 Anesthesia. Synergism has been shown between halothane anesthesia and intravenously administered labetalol. During controlled hypotensive anesthesia using labetalol in association with halothane, high concentrations (3% or above) of halothane should not be used because the degree of hypotension will be increased and because of the possibility of large reduction in cardiac output and an increase in central venous pressure.. 7.3 Nitroglycerin. Coadministration of labetalol HCl and nitroglycerine will have an additive effect in lowering blood pressure. Additionally, labetalol HCl blunts the reflex tachycardia produced by nitroglycerin. If labetalol is used in patients with angina pectoris on nitroglycerine, monitor patients blood pressure and adjust labetalol HCl injection dose as needed. In these patients, avoid initiating labetalol HCl tablets.. 7.4 Calcium Channel Blockers. Coadministration of labetalol HCl with non-dihydropyrindine calcium-channel antagonists (e.g., verapamil) is contraindicated [see Contraindications (4)]. Avoid the use of labetalol in patients receiving calcium-channel antagonists.. 7.5 Drug/Laboratory Test Interactions. The presence of labetalol metabolites in the urine may result in falsely elevated levels of urinary catecholamines, metanephrine, normetanephrine, and vanillylmandelic acid (VMA) when measured by fluorimetric or photometric methods. In screening patients suspected of having pheochromocytoma and being treated with labetalol, specific method, such as high-performance liquid chromatographic assay with solid phase extraction should be employed in determining levels of catecholamines.Labetalol has also been reported to produce false-positive test for amphetamine when screening urine for the presence of drugs using the commercially available assay methods. When patients being treated with labetalol have positive urine test for amphetamine using these techniques, confirm using more specific methods, such as gas chromatographic-mass spectrometer technique.

HOW SUPPLIED SECTION.

16 HOW SUPPLIED/STORAGE AND HANDLING. 16.1 How Supplied. Labetalol HCl in Sodium Chloride Injection is preservative-free, clear, colorless to light yellow sterile solution that is available in single-dose single-port bag with an aluminum overwrap. The container closure is not made with natural rubber latex. It is available in the following presentations: StrengthPackageNDC Number100 mg/100 mL (1 mg/mL) preservative-free1 single-dose bag0143-9363-01Box of 10 bags 0143-9363-10 200 mg/200 mL (1 mg/mL) preservative-free1 single-dose bag0143-9364-01Box of 10 bags 0143-9364-10 300 mg/300 mL (1 mg/mL) preservative-free single-dose bag0143-9365-01Box of 10 bags 0143-9365-10Labetalol HCl in Dextrose Injection is preservative-free, clear, colorless to light yellow sterile solution that is available in single-dose single-port bag with an aluminum overwrap. The container closure is not made with natural rubber latex. It is available in the following presentations: StrengthPackageNDC Number200 mg/200 mL (1 mg/mL) preservative-free1 single-dose bag0143-9366-01Box of 10 bags 0143-9366-10. 16.2 Storage. Store at 20 to 25C (68 to 77F) with excursions permitted between 15 to 30 (59 to 86 F) [see USP Controlled Room Temperature]. Do not freeze. Protect from light. DO NOT REMOVE FROM OVERWRAP UNTIL READY TO USE.

INFORMATION FOR PATIENTS SECTION.

17 PATIENT COUNSELING INFORMATION. Advise patients to remain supine and to proceed gradually in becoming ambulatory during and immediately following infusion (for up to hours) of labetalol HCl injection. Inform patient to notify their healthcare provider if they experience symptoms of hypotension. Advise patients to not interrupt or discontinue their labetalol HCl tablets without discussing with their healthcare provider and report any signs or symptoms of impending cardiac failure or hepatic dysfunction Rx OnlyManufactured byHIKMA FARMACEUTICA (PORTUGAL), S.A.Estrada do Rio da Mo, 8, 8A 8B Fervenca 2705-906 Terrugem SNT, PORTUGALDistributed byHikma Pharmaceuticals USA Inc. Berkeley Heights, NJ 07922PIN539-WES/2. Advise patients to remain supine and to proceed gradually in becoming ambulatory during and immediately following infusion (for up to hours) of labetalol HCl injection. Inform patient to notify their healthcare provider if they experience symptoms of hypotension. Advise patients to not interrupt or discontinue their labetalol HCl tablets without discussing with their healthcare provider and report any signs or symptoms of impending cardiac failure or hepatic dysfunction.

PREGNANCY SECTION.

8.1 Pregnancy. Risk Summary The extensive experience with use of labetalol in pregnant women, based on published interventional and observational studies, has not identified drug-associated risk for major birth defects, miscarriage, or adverse maternal or fetal outcomes (see Data). Untreated hypertension during pregnancy can lead to serious adverse outcomes for the mother and the fetus (see Clinical Considerations). In animal reproduction studies, oral administration of labetalol to pregnant rats and rabbits during organogenesis at doses up to approximately six and four times the maximum recommended human dose (MRHD), respectively, resulted in no fetal malformations; however, increased fetal resorptions were seen in both species at doses approximating the MRHD (see Data).In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal RiskHypertension in pregnancy increases the maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications (e.g., need for cesarean section, and post-partum hemorrhage). Hypertension increases the fetal risk for intrauterine growth restriction and intrauterine death. Pregnant women with hypertension should be carefully monitored and managed accordingly.Fetal/Neonatal Adverse ReactionsLabetalol crosses the placenta. Neonates born to mothers who are receiving labetalol during pregnancy, may be at risk for hypotension, bradycardia, hypoglycemia, and respiratory depression. Neonates should be monitored for symptoms of hypotension, bradycardia, hypoglycemia and respiratory depression and manage accordingly. Data Human Data Data from published interventional and observational studies did not demonstrate an association between major congenital malformations and the use of labetalol in pregnancy, however, most studies reported the maternal use of intravenous labetalol occurring after 20 weeks gestation.The published literature has reported inconsistent findings of intrauterine growth retardation, preterm birth and perinatal mortality with maternal use of labetalol during pregnancy; however, these studies have methodological limitations hindering interpretation. These studies cannot definitively establish the absence of risk during pregnancy. Animal DataTeratogenic studies were performed with labetalol in rats and rabbits at oral doses up to approximately six and four times the maximum recommended human dose (MRHD), respectively. No reproducible evidence of fetal malformations was observed. Increased fetal resorptions were seen in both species at doses approximating the MRHD. teratology study performed with labetalol in rabbits at intravenous doses up to 1.7 times the MRHD revealed no evidence of drug-related harm to the fetus. Oral administration of labetalol to rats during late gestation through weaning at doses of two to four times the MRHD caused decrease in neonatal survival.

USE IN SPECIFIC POPULATIONS SECTION.

8 USE IN SPECIFIC POPULATIONS. 8.1 Pregnancy. Risk Summary The extensive experience with use of labetalol in pregnant women, based on published interventional and observational studies, has not identified drug-associated risk for major birth defects, miscarriage, or adverse maternal or fetal outcomes (see Data). Untreated hypertension during pregnancy can lead to serious adverse outcomes for the mother and the fetus (see Clinical Considerations). In animal reproduction studies, oral administration of labetalol to pregnant rats and rabbits during organogenesis at doses up to approximately six and four times the maximum recommended human dose (MRHD), respectively, resulted in no fetal malformations; however, increased fetal resorptions were seen in both species at doses approximating the MRHD (see Data).In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal RiskHypertension in pregnancy increases the maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications (e.g., need for cesarean section, and post-partum hemorrhage). Hypertension increases the fetal risk for intrauterine growth restriction and intrauterine death. Pregnant women with hypertension should be carefully monitored and managed accordingly.Fetal/Neonatal Adverse ReactionsLabetalol crosses the placenta. Neonates born to mothers who are receiving labetalol during pregnancy, may be at risk for hypotension, bradycardia, hypoglycemia, and respiratory depression. Neonates should be monitored for symptoms of hypotension, bradycardia, hypoglycemia and respiratory depression and manage accordingly. Data Human Data Data from published interventional and observational studies did not demonstrate an association between major congenital malformations and the use of labetalol in pregnancy, however, most studies reported the maternal use of intravenous labetalol occurring after 20 weeks gestation.The published literature has reported inconsistent findings of intrauterine growth retardation, preterm birth and perinatal mortality with maternal use of labetalol during pregnancy; however, these studies have methodological limitations hindering interpretation. These studies cannot definitively establish the absence of risk during pregnancy. Animal DataTeratogenic studies were performed with labetalol in rats and rabbits at oral doses up to approximately six and four times the maximum recommended human dose (MRHD), respectively. No reproducible evidence of fetal malformations was observed. Increased fetal resorptions were seen in both species at doses approximating the MRHD. teratology study performed with labetalol in rabbits at intravenous doses up to 1.7 times the MRHD revealed no evidence of drug-related harm to the fetus. Oral administration of labetalol to rats during late gestation through weaning at doses of two to four times the MRHD caused decrease in neonatal survival. 8.2 Lactation. Risk SummaryAvailable published data report the presence oflabetalol in human milk at low levels. There are no data on the effects on the breastfed infant and on milk production. The developmental and health benefits of breastfeeding should be considered along with the mothers clinical need for labetalol and any potential adverse effects on the breastfed infant from labetalol or from the underlying maternal condition.. 8.3 Females and Males of Reproductive Potential. InfertilityBased on the published literature, beta blockers, including labetalol, may cause erectile dysfunction and inhibit sperm motility. 8.4 Pediatric Use. Safety and effectiveness in pediatric patients have not been established.. 8.5 Geriatric Use. Some pharmacokinetic studies indicate that the elimination of labetalol is reduced in elderly patients [see Clinical Pharmacology (12.3)]. Geriatric patients treated with labetalol could initiate therapy at the currently recommended dose of mg/minute by continuous intravenous infusion; however, lower maintenance dosages are generally required for elderly patients than nonelderly patients. Monitor blood pressure and adjust the dosage and duration of infusion accordingly until the desired response is obtained [see Dosage and Administration (2 )].

WARNINGS AND PRECAUTIONS SECTION.

5 WARNINGS AND PRECAUTIONS. Exacerbation of heart failure: Avoid use. (5.3)Acute exacerbation of coronary artery disease upon cessation of therapy: Do not abruptly discontinue. (5.4)Non-allergic bronchospasm (e.g., chronic bronchitis and emphysema): Avoid since it has not been studied. (5.5)Masked hypoglycemia: Monitor glucose as beta blockers may mask symptoms of hypoglycemia or worsen hyperglycemia. (5.6)Exacerbation of pheochromocytoma: Paradoxical increases in blood pressure may occur. (5.7)Severe hepatocellular injury: Discontinue permanently for liver injury or jaundice (5.8). Exacerbation of heart failure: Avoid use. (5.3). Acute exacerbation of coronary artery disease upon cessation of therapy: Do not abruptly discontinue. (5.4). Non-allergic bronchospasm (e.g., chronic bronchitis and emphysema): Avoid since it has not been studied. (5.5). Masked hypoglycemia: Monitor glucose as beta blockers may mask symptoms of hypoglycemia or worsen hyperglycemia. (5.6). Exacerbation of pheochromocytoma: Paradoxical increases in blood pressure may occur. (5.7). Severe hepatocellular injury: Discontinue permanently for liver injury or jaundice (5.8). 5.1 Hypotension. Symptomatic postural hypotension (incidence, 58%) is likely to occur if patients are tilted or allowed to assume the upright position within hours of receiving labetalol HCl injection. Before permitting any ambulation, establish patients ability to tolerate an upright position and observe the patient at the time of first ambulation. 5.2 Bradycardia. Bradycardia, including sinus pause, heart block, severe bradycardia, and cardiac arrest have occurred with the use of beta blockers. Monitor heart rate and rhythm in patients receiving labetalol hydrochloride injection. 5.3 Cardiac Failure. Sympathetic stimulation is vital component supporting circulatory function in congestive heart failure. Beta-blockade carries potential hazard of further depressing myocardial contractility and precipitating more severe failure. Avoid labetalol HCl injection in patients with overt congestive heart failure. If patients develop signs or symptoms of heart failure during administration, discontinue labetalol and treat appropriately. 5.4 Ischemic Heart Disease. Abrupt cessation of therapy with beta blocking agents in patients with coronary artery disease, can cause exacerbations of angina pectoris and, in some cases, myocardial infarction has been reported. Therefore, even in the absence of overt angina pectoris, after the discontinuation of labetalol HCl injection observe patients for development or worsening of angina. If patient experiences angina or angina markedly worsens or if acute coronary insufficiency develops, promptly reinstitute labetalol HCl injection and manage as unstable angina.. 5.5 Reactive Airway Disease and Nonallergic Bronchospasm. Patients with reactive airways disease should, in general, not receive beta blockers. Labetalol HCl at the usual intravenous therapeutic doses has not been studied in patients with nonallergic bronchospastic disease. In the event of bronchospasm, stop the infusion immediately, and treat as appropriate. 5.6 Use in Patients with Diabetes Mellitus and Hypoglycemia. In patients with hypoglycemia, or diabetic patients (especially those with labile diabetes) who are receiving insulin or other hypoglycemic agents, beta blockers may mask tachycardia occurring with hypoglycemia, but other manifestations such as dizziness and sweating may not be masked. Concomitant use of beta-blockers and antidiabetic agents can enhance the glucose-lowering effect of antidiabetic agents. Monitor glycemic levels in patients receiving labetalol HCl injection.. 5.7 Use in Patients with Pheochromocytoma. Intravenous labetalol has been shown to lower blood pressure and relieve symptoms in patients with pheochromocytoma; higher than usual doses may be required. However, paradoxical hypertensive responses have been reported in few patients with this tumor; therefore, monitor blood pressure when administering intravenous labetalol HCl to patients with pheochromocytoma.. 5.8 Hepatic Injury. Severe hepatocellular injury occurs rarely with labetalol therapy. The hepatic injury is usually reversible, but hepatic necrosis and death have been reported. If the patient develops signs or symptoms of liver injury, institute appropriate treatment and investigate the probable cause. Do not restart labetalol in patients without another explanation for the observed liver injury. 5.9 Use in Patients at Risk of Severe Acute Hypersensitivity Reactions. Patients at risk of anaphylactic reactions may be more reactive to allergen exposure (accidental, diagnostic, or therapeutic). Patients using beta-blockers may be unresponsive to the usual doses of epinephrine used to treat anaphylactic or anaphylactoid reactions. Avoid labetalol HCl injection in patients at high risk of anaphylactic reactions.. 5.10 Intraoperative Floppy Iris Syndrome (IFIS). IFIS has been observed during cataract surgery in some patients treated with alpha-1 blockers (labetalol is an alpha/beta blocker). This variant of small pupil syndrome is characterized by the combination of flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs, and potential prolapse of the iris toward the phacoemulsification incisions. Inform the patients ophthalmologist to be prepared for possible modifications to the surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances.