Pharmacology for Dentistry

Sympatholytics (Antiadrenergic Agents) 151

8. Cardiac arrhythmias: It is life saving
   in protecting against serious cardiac
   arrhythmias. It suppresses tachycardia.


9. Pheochromocytoma: Propranolol is
   used.


10. Hypertrophic obstructive cardiomy-
    opathy: Propranolol inhibits the inotro-
    pic effect of sympathetic stimulation
    and may reduce intraventricular pres-
    sure gradient.


11. Essential tremor: Non selective β
    blockers are useful.

Adverse Reactions & Contraindications

1. II or III degree heart block: Cardiac
   arrest may occur.


2. Bronchial asthma: An immediate
   contraction of bronchiolar smooth
   muscle prevents air from entering the
   lungs. Bronchospasm may occur in
   patient with obstructive pulmonary
   diseases.


3. Bradycardia: If it taken, resting heart
   rate reduces to 60/min or less.


4. In digitalis and verapamil therapy:
   Severe bradycardia may occur. Both
   verapamil and propranolol are
   negative inotropic agents.


5. Cardiac failure: Beta blockers depress
   myocardial contractility and may
   precipitate cardiac failure & bradycardia.


6. Cardiogenic shock.


7. Carbohydrate tolerance may be
   impaired in prediabetics.


8. Hypoglycemia.


9. Rebound hypertension & angina can
   occur on abrupt withdrawal of
   propranolol.
   10. Metabolic acidosis.
   11. Cold hand & feet.
   12. Severe haemorrhage.
   13. Tiredness & reduced exercise capacity.
   14. Can precipitate CHF by blocking
   sympathetic support to the heart.

OTHER BETA BLOCKERS

SOTALOL

It is nonselective (β 1 +β 2 ) blocking agent

with lower lipid solubility with additional

potassium channel blocking activity.

NADOLOL

It is another nonselective beta blocker

with longer duration of action and mainly

used in hypertension. It is excreted largely

in urine and does not cross blood-brain

barrier and has no central side effects.

TIMOLOL

It is nonselective agent with no local

anaesthetic activity and having excellent

ocular hypotensive effect preferred for

ophthalmic use. It is useful in chronic wide-

angle and aphakic glaucoma. Levobunolol

and betaxolol are other agents used as

ophthalmic preparation used in glaucoma.

PINDOLOL

It is a nonselective beta blocker with

marked intrinsic sympathomimetic activity.

It has advantage over propranolol that it

produces less bradycardia and rebound

hypertension. Oxprenolol resembles

propranolol and is short acting with mild

intrinsic sympathomimetic activity.

Alprenolol is similar to pindolol and

oxprenolol.