A Multicenter, Open-label Extension Study to Assess the Long-term Safety and Efficacy of an Oral Calcimimetic Agent AMG 073 (Cinacalcet) in Primary Hyperparathyroidism

Inclusion Criteria: * Successfully completed the parent study 990120 * Agreed to use highly effective (in the opinion of the principal investigator) contraceptive measures throughout the study * Were able to comprehend and were willing to give written informed consent for participation in the study Exclusion Criteria: * Pregnant or breast-feeding * Had a psychiatric disorder that interfered with the understanding and giving of informed consent or compliance with protocol requirements * Had any other condition that reduced the chance of obtaining data (eg, known poor compliance) * Participating in another investigational study at the time of study entry * Had any unstable medical condition, defined as having been hospitalized within 28 days before day 1, or otherwise unstable in the judgment of the investigator