Effect of Liver Cirrhosis on Theophylline Trough Concentrations: A Comparative Analysis of Organ Impairment Using Child-Pugh and MELD Scores

AIMS

Theophylline clearance is known to be reduced in patients with chronic liver diseases (CLDs) such as chronic hepatitis (CH) and liver cirrhosis (LC). The Child-Pugh (CP) score is generally used for pharmacokinetic evaluation, whilst a model for end-stage liver disease (MELD) has not yet been fully evaluated. This study aimed to predict theophylline clearance in patients with LC classified based on CP and MELD scores by population pharmacokinetic (PPK) analysis.

METHODS

PPK analysis included 433 steady-state trough concentrations from 192 Japanese bronchial asthma patients with and without CLDs and was performed using NONMEM. The severity of LC was assessed by CP and MELD scores.

RESULTS

The final CP and MELD models which described apparent theophylline clearance (CL/F) were obtained. The CP model showed that the mean CL/F in patients without CLDs, CH patients, and LC patients with CP class A, B, and C was 0.0473, 0.0413, 0.0330, 0.0280, and 0.0209 L/h kg-1, respectively. The MELD model predicted that CL/F in patients without CLDs, CH patients, and LC patients with MELD scores of < 10, 10-14, 15-19, 20-24, and ≥ 25 was 0.0472, 0.0413, 0.0324, 0.0268, 0.0230, 0.0197, and 0.0155 L/h kg-1, respectively.

CONCLUSIONS

CL/F in various stages of LC was evaluated, and a change in CL/F was highly dependent on the severity of CLDs in both models. The MELD model provided a more accurate and precise description of theophylline clearance in LC than the CP model, which may be due to the wider dynamic range of the MELD score.

Analysis of Plasma Concentrations of Theophylline in Smoking and Nonsmoking Patients with Asthma

BACKGROUND

While dosing theophylline in asthmatics, we should consider that a lot of medicines, substances, conditions and diseases affect the clearance of theophylline, such as smoking, macrolide antibiotics, barbiturates, oral contraceptives, heart and liver insufficiency, alcohol, calcium-antagonists, pneumonia, viral infections, hypoxemia, etc.

AIM

The aim of the study is to investigate the concentrations of theophylline during the day in smoking and nonsmoking patients with asthma.

MATERIAL AND METHODS

We have estimated the concentrations of theophylline 6 times daily by the HPLC method (Keith Muir, J Chromatography) in 20 smoking and 20 nonsmoking asthmatic patients, who were treated with theophylline sustained-release tablets 175 mg twice daily.

RESULTS

In the first group of 20 nonsmoking patients we obtained constant therapeutic and optimal concentrations of theophylline. In the second group of 20 smoking asthmatics the concentration of theophylline in plasma, in 8pm and 8am the next day was very low.

CONCLUSION

Because in smokers we have increased clearance and the decreased half- life of theophylline, and in order to prevent the night time life-threatening attacks, it is necessary to recommend maximal doses of theophylline, especially in the evening. According to the study, dosage should be individualized in order to optimize the treatment based on the measurement of theophylline concentration in plasma.