4 - PKPD of psychiatric medications (Lithium)

Question 1

List DSM-V Criteria for a manic episode

Answer 1

A: elevated, expansive or irritable mood, increased goal-oriented activity

Question 2

Lithium equations: Cl Li

Answer 2

Cl(Li) = 0.2CrCl

Question 3

Lithium clearance in non-manic

Answer 3

Cl(Li) = 0.288(CrCl)

• where Cl(Li) is lithium clearance (L/day)

Question 4

lithium clearance in manic

Answer 4

Cl(Li) = 0.432(CrCl)

• Cl(Li) in L/day

Question 5

Target Li level for acute mania

Answer 5

• 0.8 mmol/L to 1.2 mmol/L

- 1.0-1.2 mmol/L in non-responders (occasionally up to 1.5)

Question 6

.Target Li levels for maintenance

Answer 6

• 0.6 - 0.8 mmol/L (as low as 0.4 in elderly)

- 0.9 - 1.0 mmol/L in non-responders (occasionally up to 1.2 mmol/L)

Question 7

Conversion factor for mmol/L into mg/dL

Answer 7

1 mmol/L = 0.01136 mg/dL

Question 8

When is steady state achieved for lithium?

Answer 8

Achieved in 4-5 days! (because t 1/2 is 24h ; and it takes 4-5 half-lives to reach s.s.)