Adenosine 2A Agonist Lexiscan in Children and Adults With Sickle Cell Disease

Inclusion Criteria Stage I/II/IIb: (COMPLETE AND CLOSED TO ACCRUAL) * Participants must have sickle cell anemia confirmed by hemoglobin analysis * Participants must report that their pain is at baseline. Additionally, they cannot report an increase in dose or frequency of opioid use in the last 2 weeks prior to drug administration * Age 21-70 years * Participants must have the laboratory indices as outlined in the protocol * Participants must have reliable IV access as determined by the investigator * Women of child-bearing potential and men must agree to use adequate contraception prior to study entry and for the duration of the study. Inclusion Criteria Stage III: (COMPLETE AND CLOSED TO ACCRUAL) * Participants must have sickle cell anemia confirmed by hemoglobin analysis * Participant is admitted to the hospital for a pain episode * Age 21-70 years * Participants must have the laboratory indices as outlined in the protocol * Participants must have reliable IV access as determined by the investigator * Women of child-bearing potential and men must agree to use adequate contraception prior to study entry and for the duration of study participation Inclusion Criteria Stage IV: (open, still accruing volunteers) * Participants must have sickle cell disease confirmed by hemoglobin analysis * Participant is admitted to the hospital for a pain episode * Ages of assent (10 to 17 years at DFCI, but different depending on institution) * Participants must have the laboratory indices as outlined in the protocol * Participants must have reliable IV access as determined by the investigator * Participants and parents must have the ability to understand and the willingness to sign a written informed consent and assent document * Women of child-bearing potential and men must agree to use adequate contraception prior to study entry and for the duration of study participation Exclusion Criteria Stage I/II/IIb: (COMPLETE AND CLOSED TO ACCRUAL) * Participants with a current physician diagnosis of asthma (within last 12 months), require continuous supplemental oxygen, or predicted or current use of some asthma medications. * Participants with second- or third-degree AV block or sinus node dysfunction * Have a history of bleeding diathesis * Have a history of clinically overt stroke * Have a history of severe hypertension not adequately controlled with anti-hypertensive medications * Participants who are receiving chronic anti-coagulation or anti-platelet therapy * Participants with a history of metastatic cancer * Participants who have had a hospitalization or emergency room visit for any reason in the past 2 weeks * Participants may not be receiving any other study agents or have received a study agent in the past 30 days * Uncontrolled intercurrent illness * Pregnant or breastfeeding women * Participants with HIV * Participants who have previously enrolled and received the investigational agent as part of this study * Participants who are taking medications that may interact with the investigational agent Exclusion Criteria Stage III: (COMPLETE AND CLOSED TO ACCRUAL) * Participants with a current physician diagnosis of asthma (within last 12 months), require continuous supplemental oxygen, or predicted or current use of some asthma medications. * Participants with second- or third-degree AV block or sinus node dysfunction * Have a history of bleeding diathesis * Have a history of clinically overt stroke * Have a history of severe hypertension not adequately controlled with anti-hypertensive medications * Participants who are receiving chronic anti-coagulation or anti-platelet therapy * Participants with a history of metastatic cancer * Participants may not be receiving any other study agents or have received a study agent in the past 30 days Exclusion Criteria Stage IV: (open, still accruing volunteers) * Participants with a current physician diagnosis of asthma (within last 12 months), require continuous supplemental oxygen, or predicted or current use of some asthma medications. * Participants with second- or third-degree AV block or sinus node dysfunction * Have a history of bleeding diathesis * Have a history of clinically overt stroke * Have a history of hypertension not adequately controlled with anti-hypertensive medications * Participants who are receiving chronic anti-coagulation or anti-platelet therapy * Participants with a history of metastatic cancer * Participants may not be receiving any other study agents or have received a study agent in the past 30 days * Participants with HIV * Participants who have previously enrolled and received the investigational agent as part of this study * Participants who are taking medications that may interact with the investigational agent