The health care provider determines the maximum tolerable dose of isosorbide dinitrate (isordil) by increasing the dose until what happens?

Several reactions could happen after the increase of the dose, but the most important and dangerous is the abrupt decrease of blood pressure.

Explanation:

 Isordil (isosorbide dinitrate) is a medicine used for the treatment of angina or heart failure. This drug is for oral or sublingual use. It acts as a vasodilator that helps to relax smooth muscle while reducing chest pain.

  In addition to the smooth vascular muscles, Isordil relaxes the bronchial, biliary, gastrointestinal, urethral and uterine smooth muscles.  Nitrates are physiological antagonists of norepinephrine, acetylcholine and histamine. Following administration of therapeutic doses of the drug, systemic blood pressure is generally decreased; heart rate is unchanged or slightly compensatory increase.  

 If the dose was increase more than the tolerable, would happen: immediate abrupt decrease in blood pressure; persistent throbbing headache; dizziness; palpitation (feeling of rapid and strong heartbeat); visual disturbances; erythema and sweating (then the skin becomes cold); nausea and vomiting (possibly with colic and even bloody diarrhea); fainting (especially in the upright position); initial hyperpnea (increased respiratory rate), dyspnea (shortness of breath) and slow breathing; slow pulse; cardiac arrest; increased intracranial pressure with symptoms of confusion and moderate fever; paralysis and coma followed by convulsions and possibly death due to circulatory collapse.