Nifedipine-d6 is intended for use as an internal standard for the quantification of nifedipine by GC- or LC-MS. Nifedipine is a dihydropyridine L-type calcium channel blocker that reduces the amplitude of spontaneous contractions in isolated rabbit ileum when used at a concentration of 1 μM. Nifedipine (1 μM) reduces TGF-β-induced calcium oscillations in human fibroblasts and prevents impairment of lung function in a mouse model of pulmonary fibrosis induced by bleomycin when administered at a dose of 10 mg/kg per day. It also reduces increases in mean arterial blood pressure induced by angiotensin II in spontaneously hypertensive rats when administered at a dose of 10 μg/kg. Formulations containing nifedipine have been used in the treatment of hypertension and angina.