Table 7.1. Safety Ratio and Dependence Potential of Psychoactive Drugs1

Substance Effective Dose Lethal Dose Safety Ratio Dependence Potential
Narcotics        
Heroin (iv)2 8 mg 50 mg 6 Very high
  Morphine (or) 20 mg 300 mg 15 High
Depressants (sedative hypnotics)        
  Barbiturates Pentobarbital (or) 250 mg 5 g 20 Moderate/high
  Benzodiazepines Rohypnol (or) 1 mg 30 mg 30 Moderate
  Alcohol Ethanol (or) 30 mg3 300 mg 10 Moderate
Stimulants        
  Caffeine (or) 100 mg4 10 g 100 Moderate/low
  Cocaine (in) 80 mg5 1.2 g 15 Moderate/high
  Ephedra (or) 25 mg 3.5 g6 140 Moderate
  MDMA (or) 125 mg 2 g 16 Moderate/low
  Nicotine (sm) 1 mg7 50 mg 50 High
Anesthetics        
  Ketamine (in) 70 mg 2.7 g (?) 38 (?) Low
  Nitrous oxide (inh) 3.5 liters 525 liters8 150 Moderate/low
Hallucinogens        
  LSD (or) 100 mcg 100 mg 1000 Very low
  Mescaline (or) 350 mg 8.4 g (?) 24 (?) Very low
  Psilocybin (or) 6 mg 6 g (?) 1 000 (?) Very low
Cannabis        
  Marijuana (sm) 15 mg > 15 g > 1000 Moderate/low

Footnotes:

  1. The information presented here should not be used as a dosage guide. Significant differences exist with respect to a person's physiological and psychological reactions. The dosage indicated is the estimated median quantity for a 70 kg adult human who has not developed tolerance to the substance.
  2. Routes of administration: in = intranasal (insufflation/snorting), inh = inhaled, iv = intravenous, or = oral, sm = smoked.
  3. Approximately two 12-ounce beers or malt liquor at 5.5 percent by volume, or equivalent ethanol in other alcohol drinks.
  4. Approximately 1.5 cups of 148 ml (5 oz.) of fluid coffee per cup.
  5. Assumes three "lines"containing between 20 and 30 mg cocaine each.
  6. Lethal dose not clearly established;estimate based on nonhuman animal studies.
  7. Approximately one cigarette.
  8. Nitrous oxide—when used with sufficient oxygen—has not been demonstrated to be lethal.

The above table appeared in: Gable, R. S. (2006). Acute toxicity of drugs versus regulatory status. In J. M. Fish (Ed.), Drugs and Society: U.S. Public Policy, pp.149-162, Lanham, MD: Rowman & Littlefield Publishers. It was adapted in part from: Gable, Robert S. Comparison of acute lethal toxicity of commonly abused psychoactive substances. Addiction. 99. 686–696 (2004).