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[Section Outline]

The diagnosis of opioid use disorder as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) requires the repeated use of the opiate while producing problems in two or more areas in a 12-month period. The areas include tolerance, withdrawal, use of greater amounts of opioids than intended, craving, and use despite adverse consequences. A striking recent aspect of illicit opioid use has been its marked increase as the gateway to illicit drugs in the United States. Since 2007, prescription opiates have surpassed marijuana as the most common illicit drug that adolescents initially use, although overall rates of opioid use are far lower than marijuana. The most commonly used opioids are diverted prescriptions for oxycodone and hydrocodone, followed by heroin and morphine, and-among health professionals-meperidine and fentanyl.

Acute Effects !!navigator!!

All opiates have the following CNS effects: sedation, euphoria, decreased pain perception, decreased respiratory drive, and vomiting. In larger doses, markedly decreased respirations, bradycardia, pupillary miosis, stupor, and coma ensue. Additionally, the adulterants used to “cut” street drugs (quinine, phenacetin, strychnine, antipyrine, caffeine, powdered milk) can produce permanent neurologic damage, including peripheral neuropathy, amblyopia, myelopathy, and leukoencephalopathy; adulterants can also produce an “allergic-like” reaction characterized by decreased alertness, frothy pulmonary edema, and an elevation in blood eosinophil count.

Chronic Effects !!navigator!!

Tolerance and withdrawal commonly occur with chronic daily use after 6-8 weeks depending on the dose and frequency; the ever-increasing amounts of drug needed to sustain euphoriant effects and avoid discomfort of withdrawal strongly reinforce dependence once started.

Withdrawal !!navigator!!

Symptoms of opioid withdrawal begin 8-10 h after the last dose; lacrimation, rhinorrhea, yawning, and sweating appear first. Restless sleep followed by weakness, chills, gooseflesh (“cold turkey”), nausea and vomiting, muscle aches, and involuntary movements (“kicking the habit”), hyperpnea, hyperthermia, and hypertension occur in later stages. The acute course of withdrawal may last 7-10 days. A secondary phase of protracted abstinence lasts for 26-30 weeks, characterized by hypotension, bradycardia, hypothermia, mydriasis, and decreased responsiveness of the respiratory center to carbon dioxide.

Heroin users in particular tend to use opioids intravenously and are likely to be polydrug users, also using alcohol, sedatives, cannabinoids, and stimulants. In these situations the pt with opoid withdrawal might also be withdrawing from alcohol or sedatives, which might be more dangerous and more difficult to manage.

TREATMENT

Narcotic Abuse

OVERDOSE

(See Chap. 13 Narcotic Overdose)

Withdrawal

  • Principles of detoxification are to substitute a longer-acting, orally active, pharmacologically equivalent medication for the substance being used, stabilize the pt on that medication, and then gradually withdraw the substituted medication.
  • Methadone (a full mu-opioid receptor agonist) or buprenorphine (a partial agonist) are most frequently used drugs for detoxification. Dose-tapering regimens for methadone range from 2-3 weeks to as long as 180 days, but this approach is controversial given the relative effectiveness of methadone maintenance and low success rates; the vast majority of pts relapse during or after the detoxification period, indicating the chronic and relapsing nature of opioid use disorder. Buprenorphine produces fewer withdrawal symptoms compared with methadone but does not appear to produce better outcomes.
  • Several α2-adrenergic agonists have relieved opioid withdrawal and achieved detoxification by suppressing central noradrenergic activity. Clonidine and lofexidine are commonly used orally in three to four doses per day.
  • Rapid opiate detoxification can be accomplished with naltrexone combined with an α2-adrenergic agonist. Completion rates are high. Ultrarapid opiate detoxification using anesthetics is an extension of this approach but is highly controversial due to medical risks including mortality.

OPIOID MAINTENANCE

  • Methadone maintenance is widely used in management of opiate addiction. Methadone is a long-acting opioid optimally dosed at 80-150 mg/d (gradually increased over time).
  • Buprenorphine can also be used. It has a low risk of unintentional overdose but efficacy is limited to pts who need equivalent of only 60-70 mg of methadone; many pts in methadone maintenance require higher doses up to 150 mg daily. Buprenorphine is combined with naloxone at a 4:1 ratio to reduce abuse potential. A subcutaneous buprenorphine implant that lasts up to 6 months is also available.

OPIATE ANTAGONISTS FOR OPIOID DEPENDENCE

  • Rationale is that blocking the action of self-administered opioids should eventually extinguish the habit; poorly accepted by many pts.
  • Naltrexone can be given three times a week (100- to 150-mg dose); pts must first be detoxified from opioids before starting naltrexone. A depot form for monthly injection is available and improves adherence and retention, and decreases opioid use.

DRUG-FREE PROGRAMS

  • Medication-free treatments in inpatient, residential, or outpatient settings have poor 1- to 5-year outcomes compared with pharmacotherapy; exceptions are residential programs lasting 6-18 months, which require full immersion in a regimented system.

Outline ⬆

Section 15. Psychiatry and Substance Abuse