Phenytoin, Nitroglycerin and Phosphodiesterase
Phenytoin (Dilantin) is a prophylactic treatment of grand mal and psychomotor epilepsy. It is frequently combined with pheobarbital and administered orally. Side effects include sedation, blurred vision, gingivitis, G I distress, megaloblastic anemia (treated with folic acid), and osteomalacia. It can cause mental impairment. Phenytoin is also used as an antiarrhythmic agent for digoxin toxicity. Therapeutic dilantin blood level is 10 – 20 microgram/ml
Coronary vasodilators are used in the treatment of angina due to insufficient blood supply. Coronary vasodilators used in the treatment and prophylactic management of angina include nitrates, beta blockers, and calcium channel.
The nitrates used most commonly for relief of acute angina pectoris, as well as for long term prophylactic management, are nitroglycerin and isosorbide (Isordil, Sorbitrate). Isosorbide is available in capsule, tablets and sublingual forms. When using for long-term, a 12 to 14 hour nitrate free interval between the last dose of the day and the first dose of the following day is recommended to loosen the risk of nitrate tolerance.
Nitroglycerin is available in several forms, common one is sub lingual. If the relief is not attained after single dose during an acute attack, additional tablets may be administered at five minute intervals with no more than three doses given in a 15 minute period. If not relieved after 3 doses, physician should be contacted immediately.
Nitroglycerin tablets and capsules should be stored only in glass containers with tight fitting metal screw tops away from heat. Plastic containers can absorb the medication, and air, heat, or moisture can cause loss of potency. Nitro-bid ointment applied every eight hours. Nitro Dur or transderm nitro is a skin patch changed every 24 hours.
Phosphodiesterase (P D E) inhibitors such as sildenafil which is Viagra are contraindicated when taking nitrates since it can cause large, sudden, dangerous drop in blood pressure