Question

A 32-year-old male patient with asthma with an allergy to penicillin was being treated for asthmatic bronchitis with a standard-dose of oral theophylline and erythromycin. On day 8, he became irrational and confused and was taken to the emergency room by his wife. When his medications were revealed, quantitation of drugs was ordered. The theophylline level was 49 ug/dL (NRI: 10-20 ug/dL). The patient was admitted to the intensive care unit, hydrated and monitored until the theophylline level returned to normal. He then was started on a lower dose of theophylline. The patient recovered without further complications.

QUESTIONS

1. Can it be determined if this patient achieved steady state theophylline levels before measurement? The half life of theophylline in an adult is 8 hours. He had been taking the drug for 8 days. Calculate the number of half-lives. How many half lives are necessary to determine steady-state?

2. Which drug level would be of greater interest for this patient? Why?

3. At what time should blood be sampled to reflect trough and peak level concentrations? Why should "GEL BARRIER" or "SERUM SEPARATOR" tubes not be used when performing drug levels?

Answer 1

1) the steady state of theophylline level can be determined as the patient was taking oral dose for 8 day and once it reaches the steady state it shows toxic effects such as vomitting , nausea, restlessness , insomnia , serious arrhythmias , convulution . here the patient had became irrational and confused so it can be determined as the steady state of theophylline level .

The number of half lifes is 24

9 half lives are required to determine steady state

2) Inhaled corticosteriod therapy can substitute the theoplylline because it is safer and long acting bronchodilators

3) The trough level can be obtained by sampling 0 to 2 hours before the sheluded dose and the peak level after 2 to 4 hours of drug administration

The plasma concentration of the drugs is used for performing drug level and the Gel barrier or Serum seprator contains thixotropicployester gel and variour chemicals that can give false drug level