A 60-year-old male patient complains of crushing chest pain,…

A 60-year-old male patient complains of crushing chest pain, shortness of breath, and profuse sweating.  His symptoms are only slightly improved by resting.  The patient has a history of angina pectoris and has his nitroglycerin tablets with him.  Which of the following is the usual protocol for taking his nitroglycerin medication?