Labetalol

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Contents

[edit] BRAND NAMES

[edit] STRUCTURE

Labetalol.jpg

[edit] MECHANISM OF ACTION

Labetalol is a non-selective beta-adrenoceptor blocker, it blocks both β1 and β2 adrenergic receptors, reducing ability of the sympathetic nervous system to increase the myocardial contractile force and rate. Unlike conventional b-blockers Labetalol has a fast antihypertensive effect.

Labetalol is also a potent α1-adrenergic receptors blocker, it inhibits the binding of norepinephrine to the α1 receptors causing relaxation in peripheral vascular resistance which results in a decrease in blood pressure.

[edit] INDICATIONS

  • Labetalol is indicated for the treatment of hypertension, alone or in combination with other antihypertensive agents, especially thiazide and loop diuretics. It can be administered intravenously for the management of hypertensive crisis
  • Labetalol is also a first-line treatment of pregnancy-induced hypertension which is commonly associated with pre-eclampsia.

[edit] DOSAGE

  • Hypertension: The recommended initial dosage is 100 mg twice daily whether used alone or added to a diuretic regimen. After 2 or 3 days, dosage may be titrated in increments of 100 mg b.i.d. every 2 or 3 days. The usual maintenance dosage of labetalol is between 200 and 400 mg twice daily.
  • Hypertensive Emergency: 20 mg IV over 2 minutes initially, then 40-80 mg IV every 10 minutes; total dose not to exceed 300 mg. Alternative: 1-2 mg/min by continuous IV infusion; total dose of 300 mg has been used
  • Pregnancy-induced hypertension: The usual dose is 100 mg, twice a day, and may be increased weekly to a total of 800 mg, three times a day. Labetalol is safe for intravenous use as well.

[edit] CONTRAINDICATIONS

  • Bronchial asthma
  • Congestive heart failure
  • Any degree of heart block
  • Cardiogenic shock
  • Severe bradycardia
  • Patients with a history of hypersensitivity to Labetalol

[edit] PRECAUTIONS

[edit] INTERACTIONS

  • Drugs possessing beta-blocking properties can blunt the bronchodilator effect of Beta2 agonists (Antiasthmatics) in patients with bronchospasm; therefore, doses greater than the normal antiasthmatic dose of Beta2 agonists bronchodilator drugs may be required.
  • Digoxin: Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia.

[edit] PREGNANCY AND LACTATION

[edit] SIDE EFFECTS

Most adverse effects are mild and transient and occur early in the course of treatment.

Side effects include:

  • Orthostatic hypotension (due to alpha receptor blockade)
  • Dizziness
  • Fatigue
  • Drowsiness
  • Nausea
  • Erectile dysfunction
  • Paresthesia, most frequently described as scalp tingling. In most cases, it was mild and transient and usually occurred at the beginning of treatment.
  • Cold hands or feet
  • Dyspnea (respiratory distress): Rare but potentially lethal.

[edit] REFERENCES

Antihypertensives
ACE inhibitors Benazepril (Lotensin)   Captopril (Capoten)   Cilazapril   Delapril   Enalapril (Renitec, Vasotec)   Fosinopril (Monopril)  Lisinopril (Prinivil, Zestril)   Moexipril (Univasc)  Perindopril (Aceon)  Quinapril (Accupril)  Ramipril (Altace, Triatec)   Trandolapril (Mavik)  Zofenopril (Bifril, Zopranol)
Angiotensin II receptor antagonist Azilsartan (Edarbi)   Candesartan (Atacand)   Eprosartan (Teveten)   Irbesartan (Aprovel, Avapro, Karvea)   Losartan (Cozaar)   Olmesartan (Benicar, Olmetec)   Telmisartan (Micadis)   Valsartan (Diovan, Tareg)
Renin inhibitors Aliskiren (Rasilez, Tekturna)
Alpha-1 blockers Doxazosin (Cardura)   Prazosin (Minipress)   Terazosin (Hytrin)
Alpha-2 agonists (centrally acting) Clonidine (Oral route)   Clonidine (Transdermal) (Catapresan)   Guanfacine (Tenex)   Methyldopa (Aldomet)
Calcium channel blockers Dihydropyridines‎ Amlodipine (Norvasc)   Barnidipine (Vasexten)   Felodipine (Plendil)   Isradipine (Dynacirc)   Lacidipine (Lacipil, Motens)   Lercanidipine (Zanidip)   Manidipine   Nicardipine   Nifedipine (Adalat)   Nisoldipine   Nitrendipine
Benzothiazepine‎ Diltiazem (Cardizem, Taztia XT, Tiazac, Tildiem)
Phenylalkylamine‎ Gallopamil   Verapamil (Calan)
Beta blockers Beta1 selective (cardioselective) Acebutolol (Sectral)   Atenolol (Tenormin)   Betaxolol (Kerlon)   Bisoprolol (Concor)   Celiprolol (Cordiax)   Metoprolol (Betaloc, Lopressor, Toprol-XL)   Nebivolol (Bystolic, Lobivon, Nebilox)
Nonselective (Beta1 and Beta2 blockers) Oxprenolol (Trasitensin)   Propranolol (Inderal)   Timolol (Blocadren)
Nonselective (Beta1, Beta2 and Alpha1 blockers) Carvedilol (Dilatrend)   Labetalol (Trandate)
Beta blocker with intrinsic sympathomimetic activity (ISA) Acebutolol (Sectral)   Celiprolol (Cordiax)
Lipophilic Beta blockers Propranolol (Inderal)   Metoprolol (Betaloc, Lopressor, Toprol-XL)   Oxprenolol (Trasitensin)
Diuretics Carbonic anhydrase inhibitors Acetazolamide (Diamox)
Loop diuretics Bumetanide   Etacrynic acid   Furosemide (Lasix)   Piretanide   Torasemide (Demadex)
Thiazide diuretics Chlorothiazide (Diuril)   Hydrochlorothiazide (Esidrex)
Thiazide-like diuretics Chlortalidone (Hygroton)   Indapamide (Lozol, Lozide)   Metolazone
Potassium-sparing diuretics Epithelial sodium channel blockers: Amiloride (Midamor)   Triamterene (Dyrenium)
Aldosterone receptor antagonists: Potassium canrenoate   Eplerenone (Inspra)   Spironolactone (Aldactone)
Osmotic diuretics Mannitol
Combination therapy Amiloride/Hydrochlorothiazide (Moduretic)   Spironolactone/Hydrochlorothiazide (Aldactazide)