Iron Dose Calculation & Administration

Tab Ferrous Fumarate 200mg (elemental iron 66mg) 
Absorption : 10-30% (iron deficient), 5-15% (non-iron deficient)
Ferric Hexacyanoferrate Citrate, FAC (80mg elemental iron/5ml)
Oral Therapy

• The usual recommended dose in adults is 100–200 mg of elemental iron daily, in 2 to 3 divided doses.
• Lower doses may be as effective and better tolerated.
• After therapeutic doses of oral iron, reticulocytosis should occur within 72 hours, and Hb levels should rise by about 20 g/L every 3 weeks. 
• Oral iron should be continued for 3 months after anaemia has been corrected to replenish stores.
• Inadequate response to oral iron therapy can be due to a number of factors with more than one often being involved

Intravenous therapy
IV Iron Sucrose 100mg/5ml (20mg elemental iron /ml)
Calculating total body iron deficit 

• The patient’s total body iron deficit (cumulative amount of iron required to replete body iron stores) is NOT the same as the allowable iron dose per infusion which is DIFFERENT for each product.

Ganzoni formula: 
Total body iron deficit/cumulative iron dose (mg) = body weight (kg) x (target Hb – actual Hb in g/L) x 0.24* + iron depot (mg)**
*The factor 0.24= 0.0034 x 0.07 x 1,000:
*(factor is 2.4 if Hb level is measured in g/dL)
For this calculation the iron content of haemoglobin = 0.34%, blood volume = 7% of the bodyweight, and 1,000 is the conversion from g to mg
**Iron depot:
<35kg : iron depot = 15mg/kg body weight
>35kg : iron depot = 500mg

• For example a 70 kg female with Hb 80 g/L has an iron deficit of: 70 x (150 – 80) x 0.24 + 500 = 1676 mg

Administration
Infusion

• Venofer must be diluted only in sterile 0.9% m/V sodium chloride solution: 

1. 100 mg iron (5 ml Venofer) in maximum 100 ml sterile 0.9% m/V sodium chloride solution 
2. For stability reasons, dilutions to lower Venofer concentrations are not permissible. 

• As infusion, maximum tolerated single dose per day given not more than once per week: 

1. Patients above 70 kg: 500 mg iron (25 ml Venofer) in at least 3 ½ hours 
2. Patients of 70 kg and below: 7 mg iron / kg body weight in at least 3 ½ hours 

• Dilution must take place immediately prior to infusion the solution should be administered

1. 100 mg iron ( 5 ml Venofer) in at least 15 minutes 
2. 200 mg iron (10 ml Venofer) in at least 30 minutes 3 
3. 300 mg iron (15 ml Venofer) in at least 1 ½ hours
4.  400 mg iron (20 ml Venofer) in at least 2 ½ hours 

Intravenous injection:

1. Venofer can be administered undiluted by slow intravenous injection as follows: 

• 100 mg iron (5 ml Venofer) in at least 5 minutes 
• 200 mg iron (10 ml Venofer) in at least 10 minutes. 

Injection into dialyser: 

• Venofer may be administered during a haemodialysis session directly into the venous limb of the dialyser under the same conditions as for intravenous injection

References:

1. http://www.blood.gov.au/system/files/documents/iron-product-choice-dose-calc-adult
2. http://www.medsafe.govt.nz/profs/datasheet/v/venoferinf
3. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3767254/
4. iron deficient Calculator
5. http://reference.medscape.com/calculator/iron-replacement-parenteral-dosing