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- Discussion:
    - combined alpha & beta blocking agent that may be given IV w/o intrarterial monitoring;
    - for HTN, for HTN emergencies w/ IV therapy;
    - may also be used for aortic dissection;
    -  for myocardial infarction:
            - reduces mortality and infarct size and is recommended unless there are specific contraindicated;

- Dosing:
    - adult: HTN: 100mg PO bid initially; then increase by 100mg bid q 3 days;
            - maintenance: 200-400mg PO bid;
                     - continuous infusion is given at rate of 1-2 mg/min IV w/ max daily dose of 2400 mg;
            - HTN emergency: 20mg IV (slow injection);
                     - may repeat with 20-80 mg q 10 min upto max dose of 300 mg IV;
            - misc:
                     - maximum effect occurs w/in 5 min of IV injection;
                     - t1/2 = 5-8hrs
- Precautions:
      - contraindicated w/: bronchial asthma, severe bradycardia, second or third degree block, overt cardiac failure, cardiogenic shock;
      - must decrease dosage in with hepatic dysfunction;
      - use with caution when administering to patients w/:
              - pheochromocytoma (increased risk of paradoxical hyper-tensiveresponse)
              - diabetes (blunted signs of hypoglycemia)
              - cimetidine (increased bioavailability of labetolol)
              - tricyclic antidepressants (increased tremor)
              - nitrates (blunting of reflex tachycardia associatted w/ hypotension)