Protocols - Hemorio

SPECIFICITIES OF EACH OPIATE (cont’):
MORPHINE - It is a pure agonist, it does not present a maximum effect, the increase of the
dose implies in an increase of the analgesia.
- It must be prescribed when the two first steps of the analgesic ladder
proposed by WHO are inefficient.
- The risk of breathing depression is minimal in a subject who, while using
morphine, still presents pain.
- Prescribe always at a pre-determined time (usually every 4 h and eventually
in smaller intervals)
- The posology depends on the effects:
- The above limit is the presence of mild pain (up to the value 3 at the
analogical visual scale) for more than five hours during a day. Mild pain is
those supported at least for one hour before the next dose.
- The upper limit is present when side effects are present as somnolence,
vomits and constipation, making necessary sometimes the prescription of an
adjuvant drug, such as the tricyclic antidepressant, neuroleptic, etc. We start
with a 5-mg dose, which can reach 180 mg orally (eventually higher doses are
necessary). After determining the daily dose, we could prescribe morphine of a
controlled release, dividing the daily total dose for two and prescribing it, every
12 hours.
- In order to obtain the titration endovenously, 0.15 mg/kg are prescribed
adding 1mg EV every 5 minutes until a satisfactory analgesia is obtained. The
dose by hour at an infusion pump will be 1/6 of the initial dose.
- The increase of the doses in general must not be below a 25%. After about
10 days using morphine, it is believed to have a physical dependence for the
drug.
- The tolerance is developed also individually.
- The abrupt discontinuation of it will lead to the abstinence syndrome. The
abstention syndrome prevention is made with a gradual removal of the drug.
For example: When the pain is ceased, after around 10 days of continuous
usage of morphine every 4 hours, reduce half of the dose every 24 hours, not
changing the usage interval. By reaching 15 mg, open the interval and remove
for more 24 hours. This way, it will be possible the removal of the drug without
any abstinence syndrome.
- The disintoxication period depends on the usage time of the drug. For
instance, for a subject who used morphine for a year, the disintoxication period
must be 2 to 4 weeks. If he uses for about 2 months, at most in a week we will
reach the disintoxication.
METHADONE - It has opioid and non opioid properties (it is a synthetic opioid, agonist of
receptors mu and delta, and antagonist of receptors NMDA).
- It has the longest and most variable plasma half-life among the opioids and
its pharmacokinetics is individual, which may vary 12 to 15h.
- It takes approximately 5-7 days for the subject to reach the steady state.
- It does not have any active metabolic. It is release by the kidney, and
metabolized by the liver, and it may have its half-life extended by other drugs
such as amitripline or to speed up its metabolism, such as carbamezepine,
rifampicin, phenytoin, spironolactone, dilacoron, estrogen, among others.
- It has an excellent oral and rectal absorption, which may lead up to 90 h to be
fully excreted. Subjects over 65 years old and with advanced neoplasias must
receive a smaller dose. However, subjects with Falciform Disease seem to
present an increased metabolism and excretion rate, moreover during the
crisis, they need higher doses in order to have analgesia.
- Methadone IV (in Brazil, the IV preparation may cause phlebitis and must be
done diluted and slowly, it must NOT be done by PCA, because it accumulates
on the tissues)
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