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INTRODUCTION

Substance use disorder (SUD) is a lifelong illness that consists of intoxication and withdrawal from the substance that may cause euphoria. Because this illness affects brain and behavior, it results in the inability to limit or control the use of legal and illegal substances.

PATHOPHYSIOLOGY

  • The true etiology behind SUD is unknown. In general, it is felt that there needs to be a triad of the right patient, with the right genetic risk factors, being exposed to the right medication or substance in order for a SUD to occur.

CENTRAL NERVOUS SYSTEM DEPRESSANTS: CLINCAL PRESENTATION

Alcohol Use Disorder

  • Table 72-1 relates the effects of alcohol to the blood alcohol concentration (BAC).

  • Alcohol withdrawal includes (1) a history of cessation or reduction in heavy and prolonged alcohol use and (2) the presence of two or more of the symptoms of alcohol withdrawal.

  • There is 14 g of alcohol in 12 oz of beer, 5 oz of wine, or 1.5 oz (one shot) of 80-proof whiskey. This amount will increase the BAC by approximately 20–25 mg/dL (4.3–5.4 mmol/L) in a healthy 70-kg (154-lb) man. Deaths generally occur when BACs are greater than 400–500 mg/dL (87–109 mmol/L).

  • Absorption of alcohol begins in the stomach within 5–10 minutes of ingestion. Peak concentrations are usually achieved 30–90 minutes after finishing the last drink.

  • Alcohol is metabolized by alcohol dehydrogenase to acetaldehyde, which is metabolized to carbon dioxide and water by aldehyde dehydrogenase. Catalase and the microsomal alcohol oxidase system are also involved.

  • Most clinical laboratories report BAC in milligrams per deciliter. In legal cases, results are reported in percentage (grams of alcohol per 100 mL of whole blood). Thus, a BAC of 150 mg/dL = 0.15% = 34 mmol/L.

TABLE 72-1Specific Effects of Alcohol Related to Blood Alcohol Concentration

Benzodiazepines and Other Sedative–Hypnotic Misuse

  • Benzodiazepine intoxication is manifested as slurred speech, poor coordination, swaying, drowsiness, hypotension, nystagmus, and confusion.

  • Likelihood and severity of withdrawal are a function of dose and duration of exposure. Gradual tapering of dosage is necessary to minimize withdrawal and rebound ...

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