Which of the following statements best     describes long acting nitrate preparations?
Nitrates are generalized smooth-muscle dilators whose direct effect on the vasculature cannot be blocked by any currently available agents. Long acting preparations of nitroglycerin may be completely degraded by the liver in some patients and thus are generally less effective than sublingual forms. Because individual variability in metabolism is considerable, doses should be titrated against side effects and should not conform to a rigidly standardized regimen. Tolerance is common and must be considered if a patient fails to respond to a previously efficacious dose. Long-acting prep­arations such as trans dermal patches are less likely to produce the nitrate-associated side effects of headaches and dizziness than are the more rapidly acting sublingual forms.