General example of an active ingredient, with presentation, concentration and reference strength (id = "example")

<?xml version="1.0" encoding="UTF-8"?>

<Ingredient xmlns="http://hl7.org/fhir">
  <id value="example"/> 
  <!--   note this doesn't indicate an "active ingredient" as opposed to an excipient
   (for which see ingredient.role)   -->
  <status value="active"/> 
  <role> 
    <coding> 
      <system value="http://ema.europa.eu/example/ingredientRole"/> 
      <code value="ActiveBase"/> 
    </coding> 
  </role> 
  <manufacturer> 
    <manufacturer> 
      <reference value="Organization/example"/> 
    </manufacturer> 
  </manufacturer> 
  <substance> 
    <code> 
      <concept> 
        <coding> 
          <system value="http://ema.europa.eu/example/substance"/> 
          <code value="EQUIXABAN"/> 
        </coding> 
      </concept> 
    </code> 
    <strength> 
      <!--   a single strength is commonly expressed in two ways: 
         presentation - per item (e.g. per tablet), 
         and concentration - per unit of measure (usually with a unitary demoninator)
         -->
      <!--   these are not different strengths - and have the same real value - but are different
       ways of expressing the same single strength   -->
      <!--   presentation is meant for humans/consumers, concentration is meant for calculations/experts
         -->
      <presentationRatio> 
        <numerator> 
          <value value="50"/> 
          <unit value="mg"/> 
          <system value="http://unitsofmeasure.org"/> 
          <code value="mg"/> 
        </numerator> 
        <denominator> 
          <value value="1"/> 
          <unit value="tablet"/> 
          <system value="http://unitsofmeasure.org"/> 
          <code value="{tablet}"/> 
        </denominator> 
      </presentationRatio> 
      <concentrationRatio> 
        <!--   5mg/1mg (which means - because the presentation is 50mg/tablet - it must be a
         10mg tablet)   -->
        <numerator> 
          <value value="5"/> 
          <unit value="mg"/> 
          <system value="http://unitsofmeasure.org"/> 
          <code value="mg"/> 
        </numerator> 
        <denominator> 
          <!--   since this is for caculations, this is normally "1", a unitary ratio   -->
          <value value="1"/> 
          <unit value="mg"/> 
          <system value="http://unitsofmeasure.org"/> 
          <code value="mg"/> 
        </denominator> 
      </concentrationRatio> 
      <!--   A reference strength is a different strength value for the same substance, 
         expressed in terms of a related but different substance.
         This other substance is usually another chemical form of the same thing e.g.
       the "salt" form of the active igredient, 
           for example a chloride or sulfate. The salt may be the form of the substance
       molecule that is 
           actually present, even though the strength is usually expressed in terms
       of only the active "base" 
           part of the molecule.
         A tablet of morphine sulfate may acually have a stated active ingredient of
       just morphine, 
         and may express the amount (strength) of the active ingredient as 
         the mass of morphine - ignoring the mass of the sulfate group. 
         Reference strength allows for additionally expressing the amount accurately
       in terms of the entire molecule.
        -->
      <referenceStrength> 
        <substance> 
          <concept> 
            <coding> 
              <system value="http://ema.europa.eu/example/substance"/> 
              <code value="EQUIXABAN-SULPHATE"/> 
            </coding> 
          </concept> 
        </substance> 
        <strengthRatio> 
          <numerator> 
            <value value="5.03"/> 
            <unit value="mg"/> 
            <system value="http://unitsofmeasure.org"/> 
            <code value="mg"/> 
          </numerator> 
          <denominator> 
            <value value="1"/> 
            <unit value="mg"/> 
            <system value="http://unitsofmeasure.org"/> 
            <code value="mg"/> 
          </denominator> 
        </strengthRatio> 
      </referenceStrength> 
    </strength> 
  </substance> 
</Ingredient>