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Overview :
There may be advantages in switching a patient who is
receiving an intravenous medication to an oral formulation. This can be done if
there is good evidence that the patient will benefit and not be adversely
affected by the change.
Advantages of an intravenous regimen:
(1) It has more predictable kinetics, with the potential for
higher serum levels.
(2) It does not require a functional gastrointestinal tract.
(3) It does not require patient participation.
(4) Noncompliance is not a problem.
Disadvantages to an intravenous regimen:
(1) IV
formulations tend to be more expensive than the comparable oral formulation.
(2) Intravenous
administration costs are more expensive than oral.
(3) Intravenous
administration is more likely to have a complication (pain, infection,
thrombosis, etc.)
(4) A person
requiring an intravenous administration may have to return to the hospital for
dosing or have a visit from a home health nurse.
Requirements for switching to oral dosing:
(1) An appropriate oral formulation is available.
(2) There are no contraindications.
(3) The gastrointestinal tract in functional.
Appropriate oral formulation:
(1) There is an
oral formulation with a high oral bioavailability capable of delivering an
adequate amount of drug.
(2) If a
constant drug level is required, then a sustained-released formulation is
available.
(3) A oral
liquid formulation may be appropriate if the patient is unable to swallow solid
tablets or capsules.
(4) The cost of
oral therapy is less than that of parenteral administration.
Contraindications:
(1) nausea and/or vomiting
(2) ileus or bowel obstruction
(3) severe diarrhea
(4)
gastrointestinal disease, severe anasarca, bowel resection or bypass that
interferes with drug absorption
(5) coma
(6) The drug is needed to treat a critical illness and the
patient is not stable.
Evidence of a functional gastrointestinal tract:
(1) The patient
is able to tolerates a significant oral intake (clear liquids, liquid diet or
tube feedings with minimal residuals).
(2) The patient
is taking other medications by mouth.
A patient on oral therapy can be monitored if there are
questions of efficiacy:
(1) serum levels can be measured if there are questions
about absorption or peak levels.
(2) clinical monitoring of response or deterioration
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