Pharm
Hydroxyurea
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Hydroxyurea
Mechanism
Sickle Cell Anemia
Increases production of fetal
Hemoglobin
(HbF) which does not sickle
Indications
Sickle Cell Anemia
Indications in adults
Sickle Cell Crisis
3 or more times in 12 months
Severe or recurrent
Acute Chest Syndrome
Severe symptomatic chronic
Anemia
affecting functional status
Sickle cell associated pain significantly impacting function or quality of life
Indications in children over age 9 months
All children over age 9 months should be offered Hydroxyurea to reduce complications
Contraindications
Pregnancy
Lactation
Monitoring
Baseline
Complete Blood Count
with differential
Reticulocyte Count
Hemoglobin F
quantitative measurement
Comprehensive metabolic panel (
Renal Function
tests,
Liver Function Test
s)
Pregnancy Test
Labs while adjusting dose (every 4 weeks or more)
Reticulocyte Count
Complete Blood Count
with differential and platelets
Maintain
Absolute Neutrophil Count
(ANC) > 2,000/mm3
Maintain
Platelet Count
>80,000/mm3
Labs when cytopenia occurs (every 1 week)
Reticulocyte Count
Complete Blood Count
with differential and platelets
Periodic labs when on stable dose (every 2-3 months)
Reticulocyte Count
Complete Blood Count
with differential and platelets
Hemoglobin F
quantitative measurement may be obtained to evaluate for response
Management
Often managed in conjunction with
Sickle Cell Disease
specialist
Trial for minimum of 6 months before assessing efficacy
Encourage compliance for maximal effect
Starting Doses
Obtain baseline labs as above prior to initiating Hydroxyurea
Arrange reliable
Contraception
for while on Hydroxyurea
Dosing: Infants and Children
Hydroxyurea 20 mg/kg daily
Dosing: Adults with normal
Renal Function
Hydroxyurea 15 mg/kg (round up to nearest 500 mg) daily
Dosing: Adults with
Chronic Kidney Disease
Hydroxyurea 5-10 mg/kg daily
Adjusting dose
See lab monitoring as above
Maximum daily dose: 35 mg/kg/day
Decreasing dose
Indications
Neutropenia
(ANC <2000/mm3)
Thrombocytopenia
(
Platelet Count
<80,000/mm3)
Approach
Consult with specialist
In some infants and children, ANC >1250/mm3 (instead of 2000/mm3) may be acceptable
Increase lab monitoring to weekly as above
Reduce Hydroxyurea dose by 5 mg/kg/day
Increasing dose
Target ANC 2000 to 4000/mm3
Increase by 5 mg/kg/day increments every 8 weeks
Efficacy
Full benefits may not be seen for the first 6 months after starting Hydroxyurea
Reduces
Sickle Cell Anemia
mortality and hospitalizations (fewer episodes of crisis and
Acute Chest Syndrome
)
Reduces
Sickle Cell Crisis
by 50%
Steinberg (2003) JAMA 289:1645-51 [PubMed]
Resources
NIH: NHLBI Evidence-Based Management of
Sickle Cell Disease
: Expert Panel Report, 2014
https://www.nhlbi.nih.gov/health-pro/guidelines/sickle-cell-disease-guidelines
References
Yawn (2015) Am Fam Physician 92(12): 1069-76 [PubMed]
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