Dosage with a Pre-Condition - Alprazolam (id = "medadmin0311")

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

<MedicationAdministration xmlns="http://hl7.org/fhir">
  <id value="medadmin0311"/> 
  <contained> 
    <Medication> 
      <id value="med0304"/> 
      <code> 
        <coding> 
          <system value="http://www.nlm.nih.gov/research/umls/rxnorm"/> 
          <code value="308047"/> 
          <display value="alprazolam 0.25 MG Oral Tablet"/> 
        </coding> 
      </code> 
    </Medication> 
  </contained> 
  <status value="completed"/> 
  <medication> 
    <reference> 
      <reference value="#med0304"/> 
    </reference> 
  </medication> 
  <subject> 
    <reference value="Patient/pat1"/> 
    <display value="Donald Duck"/> 
  </subject> 
  <occurrencePeriod> 
    <start value="2015-01-15T22:03:00+01:00"/> 
    <end value="2015-01-16T02:03:00+01:00"/> 
  </occurrencePeriod> 
  <performer> 
    <actor> 
      <reference> 
        <reference value="Practitioner/f007"/> 
        <display value="Patrick Pump"/> 
      </reference> 
    </actor> 
  </performer> 
  <reason> 
    <concept> 
      <coding> 
        <system value="http://snomed.info/sct"/> 
        <code value="266599000"/> 
        <display value="Dysmenorrhea"/> 
      </coding> 
    </concept> 
  </reason> 
  <request> 
    <reference value="MedicationRequest/medrx0305"/> 
  </request> 
  <dosage> 
    <text value="0.25mg PO every 6-12 hours as needed for menses from Jan 15-20, 2015.  Do not exceed
     more than 4mg per day"/> 
    <route> 
      <coding> 
        <system value="http://snomed.info/sct"/> 
        <code value="26643006"/> 
        <display value="Oral Route"/> 
      </coding> 
    </route> 
    <dose> 
      <value value="1"/> 
      <unit value="TAB"/> 
      <system value="http://terminology.hl7.org/CodeSystem/v3-orderableDrugForm"/> 
      <code value="TAB"/> 
    </dose> 
  </dosage> 
</MedicationAdministration>