Effectiveness of Pharmacokinetic-Guided Hydroxyurea Dose Individualization in Patients with Sickle Cell Anemia: A Mini-Review

Inconsistent therapeutic responses have been observed among patients with sickle cell anemia (SCA) undergoing hydroxyurea (HU) following the adoption of the standardized protocol. Moreover, this treatment regimen necessitates a prolonged period to reach the maximum tolerated dose in which beneficial therapeutic effects are observed in most SCA patients. To overcome this limitation, several studies have performed HU dose adjustments in SCA patients based on individualized pharmacokinetic profiles. The present systematic mini-review aims to select and analyze published data to present an overview of HU pharmacokinetics studies performed in SCA patients, as well as evaluate the effectiveness of the dose adjustment strategy. A systematic search was performed in the Embase, Pubmed, Scopus, Web of Science, Scielo, Google Scholar, and the Virtual Library of Health databases from December 2020 to August 2022, with a total of five studies included. Inclusion criteria consisted of studies in which the dose adjustment was performed in SCA patients based on pharmacokinetic parameters. Quality analyzes were performed using QAT, while data synthesis was performed according to the Cochrane Manual of Systematic Reviews of Interventions. Analysis of the selected studies revealed improved HU treatment effectiveness using personalized dosages in SCA patients. Moreover, several laboratory parameters were utilized as biomarkers of the HU response, and methods designed to simplify the adoption of this practice were presented. Despite the scarcity of studies on this topic, HU-personalized treatment based on individualized pharmacokinetic profiles represents a viable alternative for SCA patients who are candidates for HU therapy, especially for pediatric patients. Registration number: PROSPERO CRD42022344512

Priapism in sickle cell disease: Associations between NOS3 and EDN1 genetic polymorphisms and laboratory biomarkers.

Priapism is a urologic emergency characterized by an uncontrolled, persistent and painful erection in the absence of sexual stimulation, which can lead to penile fibrosis and impotence. It is highly frequent in sickle cell disease (SCD) associated with hemolytic episodes. Our aim was to investigate molecules that may participate in the regulation of vascular tone. Eighty eight individuals with SCD were included, of whom thirty-seven reported a history of priapism. Priapism was found to be associated with alterations in laboratory biomarkers, as well as lower levels of HbF. Patients with sickle cell anemia using hydroxyurea and those who received blood products seemed to be less affected by priapism. Multivariate analysis suggested that low HbF and NOm were independently associated with priapism. The frequency of polymorphisms in genes NOS3 and EDN1 was not statistically significant between the studied groups, and the presence of the variant allele was not associated with alterations in NOm and ET-1 levels in patients with SCD. The presence of the variant allele in the polymorphisms investigated did not reveal any influence on the occurrence priapism. Future studies involving larger samples, as well as investigations including patients in priapism crisis, could contribute to an enhanced understanding of the development of priapism in SCD

Sickle cell disease: A distinction of two most frequent genotypes (HbSS and HbSC).

Sickle cell disease (SCD) consists of a group of hemoglobinopathies in which individuals present highly variable clinical manifestations. Sickle cell anemia (SCA) is the most severe form, while SC hemoglobinopathy (HbSC) is thought to be milder. Thus, we investigated the clinical manifestations and laboratory parameters by comparing each SCD genotype. We designed a cross-sectional study including 126 SCA individuals and 55 HbSC individuals in steady-state. Hematological, biochemical and inflammatory characterization was performed as well as investigation of previous history of clinical events. SCA patients exhibited most prominent anemia, hemolysis, leukocytosis and inflammation, whereas HbSC patients had increased lipid determinations. The main cause of hospitalization was pain crises on both genotypes. Vaso-occlusive events and pain crises were associated with hematological, inflammatory and anemia biomarkers on both groups. Cluster analysis reveals hematological, inflammatory, hemolytic, endothelial dysfunction and anemia biomarkers in HbSC disease as well as SCA. The results found herein corroborate with previous studies suggesting that SCA and HbSC, although may be similar from the genetic point of view, exhibit different clinical manifestations and laboratory alterations which are useful to monitor the clinical course of each genotype