Sickle Cell Disease Vaso-occlusive Crisis

This is a phase 2, randomized, multiple-dose, placebo-controlled study designed to evaluate the safety, efficacy, and pharmacokinetics (PK) of CSL889 (human hemopexin) when given intravenously (IV) to adults and adolescents with sickle cell disease (SCD) experiencing vaso-occlusive crises (VOC). The main objectives of the study are to evaluate the safety and tolerability of CSL889 in study participants, and to assess how CSL889 affects the time it takes for VOC to resolve in participants with SCD.

The goal of this clinical trial is to learn whether a single dose of buccal buprenorphine (BELBUCA) is safe when used in place and/or with full agonist opioids that would otherwise be started during a sickle cell pain crisis admission, in adolescents and young adults (ages 12-22) with sickle cell disease (SCD) who are hospitalized for acute pain. The main questions it aims to answer are: * Is a single dose of buccal buprenorphine, given at doses between 75 and 450 micrograms, safe in this population? * Does buccal buprenorphine reduce the amount of full agonist opioid pain medicine participants need through their patient-controlled analgesia (PCA) pump, and does it change pain scores? * Are participants and their care team satisfied with pain management when buccal buprenorphine is used? * What are the pharmacokinetic properties (how the body absorbs, distributes, and clears the drug) of buccal buprenorphine in this age group? This is a single-arm, open-label, dose-escalation study: every participant receives buccal buprenorphine, and there is no placebo or separate comparison group. Instead, researchers will compare each participant's own opioid use and pain scores in the 8 hours before receiving buccal buprenorphine to the 8 hours afterward, to see whether the dose reduces the need for additional opioid pain medicine. Participants will: * Be treated first with standard-of-care patient-controlled analgesia (PCA) pain medicine (hydromorphone) during the early, acute-stabilization phase of their hospital stay. * Once their pain is stable and they meet criteria to transition to oral opioids, as would happen under usual care, they will receive a single dose of buccal buprenorphine instead, at a dose (75, 150, 300, or 450 micrograms) assigned according to a dose-escalation design. * Continue to have access to demand-only PCA pain medicine for breakthrough pain after the study dose. * Undergo continuous monitoring of heart rate, oxygen level, and carbon dioxide level, plus pain and sedation checks every 4 hours, for 48 hours after the dose. * Have blood samples collected, only when blood is already being drawn for clinical care, to help study how the body processes the drug. * Complete a brief satisfaction survey about their pain management after the dose. * Be contacted by phone or telehealth, and have their medical record reviewed, 30 days after the dose to check for any safety concerns.