Plasma theophylline concentration and lung function in ponies with recurrent obstructive lung disease.

The research article studies the effects of a drug named aminophylline on lung function in ponies diagnosed with recurrent obstructive lung disease. The researchers determined that the appropriate therapeutic dosage of the drug is between 59 and 84 mumol/litre, below which the drug fails to act as a bronchodilator, and above which, it causes excitability and an increased heart rate.

Research Participants and Methodology

• The researchers selected six ponies that had been diagnosed with recurrent obstructive lung disease to participate in the study.
• Each of these ponies was studied separately across two different sessions that lasted for 60 minutes each. In these sessions, they were given matching doses of either aminophylline or sterile water.
• To measure the effects of the substances, the researchers kept tabs on a variety of factors including dynamic lung compliance, pulmonary resistance, respiratory rate, tidal volume, blood gas tensions, and heart rate.
• The researchers collected plasma samples at 10-minute intervals throughout the infusion period to measure the concentration of theophylline in the ponies’ bloodstream.
• The ponies’ level of excitability was analyzed subjectively at the same intervals.

Research Findings

• According to a previously published model, the ponies’ plasma theophylline concentrations were accurately predicted by the researchers.
• The sterile water that was given to the ponies had no noticeable impact on their lung function.
• Contrastingly, the administration of aminophylline had significant effects on the ponies’ lung functions compared to their baseline metrics.
• Resistance in the ponies decreased after 30 minutes when their mean plasma theophylline concentration was approximately 59 mumol/litre.
• Compliance increased at 60 minutes when their mean plasma theophylline concentration was approximately 102 mumol/litre.
• All the ponies exhibited signs of excitement between 40 and 50 minutes, and their heart rate increased at 50 minutes.

Conclusions

• The researchers concluded that when administering aminophylline intravenously, the therapeutic dosage for iv theophylline concentration in ponies suffering from ‘heavey’ should be between 59 and 84 mumol/litre.
• When the concentration was below 59 mumol/litre, the researchers did not observe any consistent bronchodilator activity from the drug.
• Conversely, when the concentration surpassed 84 mumol/litre, the ponies’ excitement and increased heart rate (tachycardia) reduced the effectiveness of the drug.