an effective dose is established, attempt to limit dosage to this level. This goal is facilitated by use of a written treatment contract that specifically prohibits early refills and having multiple prescribing physicians.
using nonopioid analgesics whenever possible. Especially in chronic management, consider using other types of analgesics or compounds exhibiting less pronounced withdrawal symptoms on discontinuance.
evaluate continuing analgesic therapy and the patient’s need for opioids.
the rights, responsibilities, and roles of patients and providers regarding controlled substances. If there are concerns about the patient’s safety, difficult decisions may need to be made.
B. Diagnosis and Treatment of Opioid Overdosage
Intravenous injection of naloxone dramatically reverses coma due to opioid overdose but not that due to other CNS depressants. Use of the antagonist should not, of course, delay the institution of other therapeutic measures, especially respiratory support. (See also The Opioid Antagonists, below, and Chapter 58.) The growing epidemic of prescription opioid use and opioid-related adverse drug reactions has been accompanied by an even greater increase in heroin-related deaths in the United States from 2010 to 2014. For this reason, attention is being directed to make naloxone via intramuscular and intranasal routes widely available, including as over-the-counter formulations.
C. Contraindications and Cautions in Therapy 1. Use of pure agonists with weak partial agonists—When a weak partial agonist such as pentazocine is given to a patient also receiving a full agonist (eg, morphine), there is a risk of diminishing analgesia or even inducing a state of withdrawal; thus combining a full agonist with partial agonist opioids should be avoided.
2.
Use in patients with head injuries—Carbon dioxide retention caused by respiratory depression results in cerebral vasodilation. In patients with elevated intracranial pressure, this may lead to lethal alterations in brain function.
3.
Use during pregnancy—In pregnant women who are chronically using opioids, the fetus may become physically dependent in utero and manifest withdrawal symptoms in the early postpartum period. A daily dose as small as 6 mg of heroin (or equivalent) taken by the mother can result in a mild withdrawal syndrome in the infant, and twice that much may result in severe signs and symptoms, including irritability, shrill crying, diarrhea, or even seizures. Recognition of the problem is aided by a careful history and physical examination. When withdrawal symptoms are judged to be relatively mild, treatment is aimed at control of these symptoms using such drugs as diazepam; with more severe withdrawal, camphorated tincture of opium (paregoric; 0.4 mg of morphine/mL) in an oral dose of 0.12–0.24 mL/kg is used. Oral doses of methadone (0.1–0.5 mg/kg) have also been used.
4.
Use in patients with impaired pulmonary function—
In patients with borderline respiratory reserve, the depressant properties of the opioid analgesics may lead to acute respiratory failure.
5. Use in patients with impaired hepatic or renal function—
Because morphine and its congeners are metabolized primarily in the liver, their use in patients in prehepatic coma may be questioned. Half-life is prolonged in patients with impaired renal function, and morphine and its active glucuronide metabolite may accumulate; dosage can often be reduced in such patients.
6. Use in patients with endocrine disease—Patients with adrenal insufficiency (Addison’s disease) and those with hypothyroidism (myxedema) may have prolonged and exaggerated responses to opioids.
Because seriously ill or hospitalized patients may require a large number of drugs, there is always a possibility of drug interactions when the opioid analgesics are administered. Table 31–5 lists