The only absolute contraindication to<unk>  is an allergy to<unk>  or any other dihydropyridines. Other situations occur, however, where<unk>  generally should not be used. In patients with cardiogenic shock, where the heart's ventricles are not able to pump enough blood, calcium channel blockers exacerbate the situation by preventing the flow of calcium ions into cardiac cells, which is required for the heart to pump. While use in patients with aortic stenosis (narrowing of the aorta where it meets the left ventricle) since it does not inhibit the ventricle's function is generally safe, it can still cause collapse in cases of severe stenosis. In unstable angina (excluding variant angina),<unk>  can cause a reflex increase in cardiac contractility (how hard the ventricles squeeze) and heart rate, which together increase the demand for oxygen by the heart itself. Patients with severe hypotension can have their low blood pressure exacerbated, and patients in heart failure can get pulmonary edema. Those with impaired liver function are unable to metabolize<unk>  to its full extent, giving it a longer half-life than typical.<unk> 's safety in pregnancy has not been established, although reproductive toxicity at high doses is known. Whether<unk>  enters the milk of breastfeeding mothers is also unknown. Those who have heart failure, or recently had a heart attack, should take<unk>  with caution.
Amlodipine
Cyclothiazide
Chlorothiazide
Felodipine
Hydrochlorothiazide
Telmisartan
Spironolactone
Olmesartan