Opioids

Although some of the drugs included in the tables have been used for centuries (e.g., ALCOHOL, CAFFEINE), knowledge of their kinetics and metab-

olism is very recent and, in some cases, still incom-

TABLE 1

Pharmacokinetic Parameters of Opioids

TABLE 1

Pharmacokinetic Parameters of Opioids

Bioavail

Protein

Mean ti/2

Dosage/Route

ability (F)

Binding

tmnx

(h)

Vd

CI

Drug

(mg)

(o/o)

(o/o)

(h)

(range)

(L/kg)

(ml/min/kg)

Butorphanol

2/IV

100 (IM)

80

0.75

3-4

5

385

Codeine

60 oral/IV

40-80 (oral)

7-53

1

(2.3-9.3)

2-6

15

Dextromethorphan

>50 (oral)

30-50

(estimated)

3-5

Heroin

4-16/IV

79 (oral)

-

-

3.0 min

-

31

(3,6 diacelylmorphine)

utes

(see morphine)

Buprenorphine

0.3/IV

40-90 (oral)

2-3

1-3

900-1,200

(ml/min)

Pentazocine

-

47 (oral)

65

-

4.5

7

17

Morphine

0.01/mg/kg

15-64 (oral) 100 (IM) 48 (rectal) 2 (epidural)

35

<1

2-4

3-4

12-21

Methadone

15-80

92 (oral)

40

<1

(13-47)

3.8

1.4

Meperidine

50-100/IM

50-60 (oral)

50-60

-

3-4

3-5

Propoxyphene

130

40-90 (oral)

-

1-2

2-15

Nalbuphine

-

16 (oral)

-

1-2

2-3

3-4

22

Naltrexone

5-40 (oral)

20

2-3

19

48

Vd = Volume of distribution CI = Clearance IV = Intravenous IM = Intramuscular

Vd = Volume of distribution CI = Clearance IV = Intravenous IM = Intramuscular

TABLE 2

Pharmacokinetic Parameters of Stimulant Drugs

TABLE 2

Pharmacokinetic Parameters of Stimulant Drugs

Bioavail

Protein

Mean ti/2

CI

Dosage/Route

ability (F)

Binding

^ max

(h)

Vd

(ml/min/

Drug

(ms)

(o/o)

(o/o)

(h)

(range)

(L/kg)

kg)

Amphetamine

15-25/oral

-

23-26

1.25

14 (2-22)

(L/min)

Caffeine

1—5 mg/kg/ oral

100 (oral)

15-40

0.5-1

(1-10)

0.6

1

Cocaine

30-100/IV;IN

28-51 (IN)

7

0.5-1.5

(0.3-1.5)

2

11

(mg/kg/min)/ IV

30

5

(0.8-3.5)

1-2

18

Vd = Volume of distribution CI = Clearance IV = Intravenous IN = Intranasal

Vd = Volume of distribution CI = Clearance IV = Intravenous IN = Intranasal

TABLE 3

Pharmacokinetic Parameters of CNS Depressants

TABLE 3

Pharmacokinetic Parameters of CNS Depressants

Bioavail

Protein

Mean ti/2

Dosage/Route

ability (F)

Binding

(h)

Vd

CI

Drug

(mg)

(o/o)

(0/0)

(h)

(range)

(L/kg)

(ml/min/kg)

Alcohol (ethanol)

80 (oral)

-

<1

0.25

0.5

124 mg/kg/h

Benzodiazepines:

Alprazolam

0.5-30/oral

90 (oral)

70

0.7-1.6

12 (6-18)

0.7-1.5

0.7-1.3

Bromazepam

0.25—3/oral

-

70

1

10-15

-

-

Chlordiazepoxide

20-50/oral IV, IM

100 (oral) PO or (IM)

95

0.5-3

10 (6-28)

0.3

0.5

Clobazam

10-20/oral

Good (oral)

90

1.3-1.7

(16-49)

0.9-1.8

0.36-0.63

Clonazepam

-

98

86

1-2

23 (20-80)

3.2

1.55

Clorazepate (see

-

-

-

-

2.0

0.33

1.8

Desmethyldiazepam)

Desalkylflurazepam

1

(40-200)

22

4.5

Desmethyldiazepam

-

99

97

1-2

(51-120)

0.78

0.14

Diazepam

1—40/oral IM, IV

100 (oral) 50-60 (IM, rectal)

96

0.5-2

(14-61)

(0.9-3.0)

0.38-0.51

Flurazepam (see

15—90/oral

-

97

-

-

Desalkylflurazepam)

Halazepam (see

-

Desmethyldiazepam)

Lorazepam

2—4/oral

93 (oral) 90 (IM)

90

1.5

(8-25)

0.8-1.6

(0.8-1.3)

Midazolam

5—15/oral IV, IM

44 (oral)

95

0.3-0.7

1.4-5

0.8-17

6

Nitrazepam

15-30/oral

78 (oral)

87

2

(16-48)

1.2-2.7

0.86

Oxazepam

15-45/oral

97 (oral)

98

(0.5-8)

(5.1-13)

0.5-2.0

0.6-2.9

Prazepam (see

Desmethyldiazepam)

Temazepam

10-30/oral

>80 (oral)

98

0.8-4.7

(7-17)

1.3-1.5

1.0-3.4

Triazolam

0.25-1.0/oral

44 (oral) 53 s.l.

90

1.6

2.5 (2-5)

1.1

3.7-8.8

Vd = Volume of distribution CI = Clearance IV = Intravenous IM = Intramuscular s.l. = Sublingual

Vd = Volume of distribution CI = Clearance IV = Intravenous IM = Intramuscular s.l. = Sublingual plete. This is due partly to their complex metabolism and partly to the difficulties of studying drugs of abuse in humans.

The tables show the route of administration, the type of subjects used in the study, the doses used, and the most important kinetic parameters such as protein binding, half-life, volume of distribution, and clearance.

(SEE ALSO: Drug Metabolism; Pharmacogenetics; Pharmacokinetics of Alcohol)

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