Drug Interaction:
Beta-adrenergic blockers include- Atenolol, Acebutol, Betaxolol, Bisoprolol,Cartelol,Esmolol, Labetatol,Metoprolol, Nadolol,Penbutolol, Pinodol, Propranolol, Solatol, Timolol, Refer - Atenolol
Indication:
Hypertension
Beta-adrenergic blockers include- Atenolol, Acebutol, Betaxolol, Bisoprolol,Cartelol,Esmolol, Labetatol,Metoprolol, Nadolol,Penbutolol, Pinodol, Propranolol, Solatol, Timolol, Refer - Atenolol
Adverse Reaction:
Oral
CNS- fatigue, headache, drowsiness, paresthesias, rare instances of syncope, GU- ejaculation failure, impotance, priapism, difficulty in mitturition, acuter urinary bladder retention, GI- diarrhea, cholestatis with or without jaundice, reversible increases in serum transaminase. Respirarory- dyspnea, bronchospasm.
Musculoskeletal
asthenia, muscle cramps, toxic myopathy Dermatologic- rashes such as generalized maculopapular, lichenoid, urticarial, bulous lichen planus, psoriaform,facial erythema, reversible alopecia Miscellaneous- systemic lupus erythematous,postive antinuclear factor (ANF), antimitochondrial antibodies, edema,nasal stuffiness, fevere, vision abnormality, dry eyes. pruritus, flushing,
Parentral
CNS- hypoesthesia (numbness ) somnolence/yawning Cardiovascular- ventricular arrhythmias Renal- transcient increases in BUN and serum creatinine, associated with drops in BP , generally in patients with prior renal insufficiency Adverse effects not listed above have not been reported with other Beta-adrenergic blockers- CNS- mental depressin progressing to cataonia,acute reversible syndrome characterrized by disorientation for time/place, short term memory loss, emotional lability, clouded sensorium and decreased performance on neuropsychometrics. Cardiovascular- intensification of AV block
Hypersentivity
fever with aching and sore throat, laryngospasm, rspiratory distress Hematogic -agranulocytosis,theombocytopenia/nonthrombocytopenic purpura GI- mesentric artery thrombosis,ischemic colitis.
Contra-Indications:
2nd & 3rd degree heart block,cardiogenic shock,prolonged hypertension,severe bradycardia. Hypersens to the drug, bronchospasm. Special precautions: Patients with liver diseases may require lower dose.
Asthma. Concomittant administration of class 1 anti-arrhythmic agents,calcium agonists.Patients especially those with IHD should not interupt/discontinue the drug abruptly.Diabetes. Hypotension- following oral administration ,postural hypotension has been transcient and is uncommon when the recommended starting dose and tiration are strictly are closely followed. Establish patients ability to tolerate upright postion before permitting ambulation.
Warnings
Cardiac failure- CHF has been observed in patients receiving labetolol. Patients with a history of cardiac failure- at first sign or symptom of impending cardiac failure, fully digitalize or give diuretic, observe closely. If cardiacfailure continues, withdraw (gradually,if possible).
Wthdrawal
angina has not been reported upon discontinuation. However, If angia markedly, worsens,or acute coronary insufficiency develops, reinstitute promptly, at laest temporarily, and take other measures.
Nonallergic bronchospasm
patients with bronchospastic disease should not in genewral receive beta-blockers. Labetolol can be used with caution, however, in patients whodo not respond to, or cannot tolerate other antihypertensives agents, use the smallest effective dose. Diabetes mellitus and hypoglycemia- beta-blockade reduces insulin release in response to hyperglycemia,it may be neccessary to adjust drug dose.
Major surgery
withdrawing beta blockers prior to major surgery has been contraversial. Protracted severe hypotension and difficulty in restarting or maintaing heart beat have been reported with beta-blockers, labetolol has not been evaluated in this setting.
Rapid decreases of BP- observe caution when reducing severely elevated BP. Acheive BP lowering over as long a time as possible.
Hepatic function impairment- use with caution,drug metabolism may be diminshed.
Pregnancy
use during pregnancy only if potentail benefits outweigh potential hazards to the fetus.
Lactation
excercise caution when administering to a nursing woman.
Children
safety and efficacy for use in children have not been established.
Dosages/ Overdosage Etc:
Indications:
Hypertension Dosage: Individualise dosage. 100mg twice daily,alone or added to diuretic.
Maintenance
200 to 400mg twice daily. Patients with severe hypertension may require 1.2 to 2.4g/day. Titration increment should not exceed 200mg twice a day.
Overdosage-
Symptoms Excessive hypotension which is posture-sensitive, excessive bradycardia Treatment
1. Institute gastric lavage or induce emesis to remove drug after oral ingestion
2. Place patient in supine position, raise legs if necessary.
3. Employ these as needed.-
i. Excssive bradycardia- administer atropine or epinephrine
ii. Administer a digitalis glycoside and a diuretic. Dopamine or dobutamine may also be useful.
iii. Hypotension- administer vasopressors. norephinephrine may be a drug of choice.
iv. Bronchospasm- administer epinephrine or an aerosolized beata 2 -agonist
v. Administrer diazepam
vi. Severe betablocker overdose- resulting inhypotension or bradycardia, glucogon has been effective in large doses ( 5 to 10mg rapidly over 30 seconds, followed by continous infusion of 5mg/hr, reduce as patient improves vii. Neither hemodialysis nor peritoneal dialysis removes a significant amount of labetolol from the general circulation ( < 1%)
Missed dose
1. Do not miss any doses.This is specially important when yountaking one dose per day. Some conditions may become worse oif not taken regularly.
2. If you do miss a dose take it as soon as possible.
3. However, if it is within 4 hours of your next dose ( 8 hours when using atenolol, betaxolol, bisoprolol,carteolol, labetalol, nadolol, pnbutolol,solatol, or extended release (long acting) metoprolol, oxyprenol, or propranolol) skip the missed dose and go back to your dosing schedule
4. Do not double doses.
Patient Information:
Beta-adrenergic blockers include- Atenolol, Acebutol, Betaxolol, Bismoprolol,Cartelol,Esmolol, Labetatol,Metoprolol, Nadolol,Penbutolol, Pinodol, Propranolol, Solatol, Timolol, Refer - Atenolol
1.Do not discontinue medication except on advice from physician
2.Consult physician at any sign of impending cardiac failure.
3.Transcient scalp tingling may occur,especially when treatment is initiated.
Pharmacology/ Pharmacokinetics:
Pharmacology:
Labetalol produces dose-related fall in BP without reflex tachycardia or significant reduction in heart rate.
Pharmacokinetics:
Oral labetalol is completely absorbed,peak plasma levels occur in 1 to 2 hours. Steady-state plasma levels during repititive dosing are reached by about the third day.
Metabolism:
Metabolism is mainly through conjugation to glucoronide metabolites,which are excreted in urine and feces(via bile). Elimination half-life following oral is 6 to 8 hours and 5.5 hours respy.
Interaction with Food:
Bioavalilabilty increased by food.
Pregnancy and lactation:
Pregnancy
Use during pregnancy only if potentail benefits outweigh potential hazards to the fetus.
Lactation
Excercise caution when administering to a nursing woman.
Children
Safety and efficacy for use in children have not been established.