V
itamins are substances that the body
requires for carrying out essential
metabolic reactions. The body cannot
synthesise enough of these components
to meet all of its needs; therefore, they
must be obtained from animal and vege-
table tissues taken in as food. Vitamins
are only needed in small amounts
because they function as coenzymes
that activate the protein portions of
enzymes, which catalyse a great deal
of biochemical activity. Vitamins are
either water soluble and excreted in
the urine or they are fat soluble and
capable of being stored in adipose
tissue in the body.
Therapeutic actions and indications
Vitamins act as coenzymes to activate a variety of
proteins on enzymes that catalyse biochemical activity.
They are indicated for the treatment of vitamin deficien-
cies, as dietary supplements when needed and as specific
therapy related to the activity of the vitamin.
Contraindications and cautions
These drugs are contraindicated in the presence of any
known allergy to the drug or the colourants, additives
or preservatives used in the drug. Some are used to
maintain adequate vitamin levels during pregnancy and
breastfeeding.
Adverse effects
The adverse effects primarily associated with these
drugs are related to gastrointestinal upset and irritation,
which is caused by direct gastrointestinal contact with
the drugs.
Clinically important drug–drug interactions
Pyridoxine—vitamin B
6
—interferes with the effec-
tiveness of levodopa. Fat-soluble vitamins may not
be absorbed if given concurrently with mineral oil,
cholestyramine or colestipol.
Appendix
Vitamins
E
Care considerations
Assessment
■
■
Obtain a nutritional assessment. Screen for any
medical conditions and drugs being taken and for
any known allergies.
■
■
Evaluate skin and mucous membranes, as well as
pulse, respirations and blood pressure. Full blood
count (FBC) and clotting times may need to be
evaluated with specific vitamins.
Implementation
■
■
Assess the person’s general physical condition
before beginning test
to decrease the potential for
adverse effects and ensure need for the drug.
■
■
Advise the person to avoid the use of over-the-
counter preparations that contain the same
vitamins
to prevent inadvertent overdose of the
vitamin.
■
■
Provide comfort measures
to help the person
tolerate drug effects
(e.g. take drug with meals to
alleviate gastrointestinal distress).
■
■
Include information about the solution being used
in a test (e.g. what to expect, adverse effects that
may occur, follow-up tests that may be needed)
to enhance knowledge about drug therapy and
promote compliance with drug regimen.
Evaluation
■
■
Monitor response to the drug (adequate vitamin
intake).
■
■
Monitor for adverse effects (GI upset).
■
■
Evaluate the effectiveness of the teaching plan
(person can name adverse effects to watch for
and specific measures to avoid them; person
understands the importance of follow-up that
will be needed).
■
■
Monitor the effectiveness of comfort measures
and compliance with the regimen.
