Theophylline

Question 1

What two formulations are given for theophylline?

Answer 1

PO

IV

Question 2

What is the percentage of absorption for theophylline PO?

Answer 2

100%

Question 3

What is the percentage of absorption for theophylline IV?

Answer 3

80%

Question 4

Is it best for theophylline to be administered with food or without food? Why or why not?

Answer 4

Without food - can increase the absorption and toxicities with food

Question 5

What is the volume of distribution (Vd) for theophylline?

Answer 5

0.4 to 0.6 L/kg

Question 6

Where is theophylline mainly metabolized?

Answer 6

Hepatic metabolism (> 90%)
FYI = CYP1A2 (mainly), 3A4, 2E1

Question 7

(T/F) - Smoking cessation (stopped smoking) can decrease theophylline concentration

Answer 7

FALSE - it increases concentrations

Question 8

Where is theophylline eliminated/excreted?

Answer 8

10% unchanged in urine

Question 9

Are renal dose adjustments needed for the theophylline in renal failure patients?

Answer 9

No

Question 10

Is theophylline given before or after hemodialysis (HD)?

Answer 10

After - eliminated by HD

Question 11

What is the half-life of theophylline?

Answer 11

T 1/2 = 5 to 24 hours

Question 12

In which 2 patient populations is theophylline’s half-life prolonged?

Answer 12

• Premature or mature neonates

- Patients > 65 yo

Question 13

What 4 things can increase theophylline clearance?

Answer 13

• Inducers of CYP1A2 and 3A4
• Hyperthyroidism
• Diet charbroiled foods
• Low CHO/high protein diet

Question 14

Name 5 inducers of CYP1A2 and 3A4

Answer 14

• Smoking (any type of smoking)
• Carbamazepine
• Phenobarbital
• Phenytoin
• Rifampin

Question 15

What 5 things can decrease theophylline clearance?

Answer 15

• Inhibitors of CYP1A2 and 3A4
• Cirrhosis or acute hepatitis
• Heart failure
• Hypothyroidism
• Low protein/high CHO

Question 16

Name 6 inhibitors of CYP1A2 and 3A4

Answer 16

• Ciprofloxacin
• Macrolides
• Azole antifungals
• Oral contraceptives
• Protease inhibitors
• Verapamil

Question 17

What are the names of the extended-release theophylline tablets and capsules?

Answer 17

Theo-24
Theocron
Theo-Dur

Question 18

Is theophylline a prodrug in the IV form?

Answer 18

YES

Question 19

There are two general dosing rules, name 1 regarding the weight that should be used to calculate doses

Answer 19

Use TBW (Act. BW) for dosing unless the patient is obese, then use the IBW

Question 20

There are two general dosing rules, name 1 regarding the blood concentration

Answer 20

For every 1 mg/kg of theophylline, blood concentrations will rise ~ 2 mg/L

Question 21

What is the maintenance dose (MD) of theophylline orally given in most patients (healthy)? What is the max dose?

Answer 21

10 mg/kg/day

Max = 900 mg/day

Question 22

What is the MD of theophylline orally given in patients who have HF or liver dysfunction?

Answer 22

5 mg/kg/day

Max = 400 mg/day

Question 23

What is the MD of theophylline given IV?

Answer 23

0.5 mg/kg/hr

Question 24

What is the therapeutic range of serum concentrations in adults taking theophylline?

Answer 24

5 to 15 mg/L

Question 25

Is it acceptable for serum concentrations to reach 20 mg/L?

Answer 25

Yes - in some patients

Question 26

What is the therapeutic range of serum concentrations in neonates taking theophylline?

Answer 26

6 to 13 mg/L

Question 27

In normal serum concentrations, what side effects can occur?

Answer 27

• N/V
• Dyspepsia
• Nervousness
• Insomnia
• HA
• Tachycardia

Question 28

What side effects can occur in serum concentrations ranging from 20 to 30 mg/L?

Answer 28

Tachyarrhythmias

Question 29

What side effects can occur in serum concentration > 40 mg/L?

Answer 29

• Life threatening arrhythmias

- Seizures