Clinical efficacy and safety of clenbuterol HCl when administered to effect in horses with chronic obstructive pulmonary disease (COPD).

The study investigates the effectiveness and safety of a drug called clenbuterol HCl in treating horses with Chronic Obstructive Pulmonary Disease (COPD). It showed that incremental administration of clenbuterol improved clinical conditions in 75% of horses, with minor side effects occurring infrequently.

Research Methodology and Treatment Plan

• The researchers conducted a study with a total of 239 horses suffering from COPD.
• The severity of the disease, also known as ‘heaves’, and the response to treatment was determined through clinical evaluation.
• An “overall ‘heaviness rating'” (OHR) was assigned to each horse at every observation to track the progression of the disease and the effectiveness of the treatment.
• The treatment plan involved an oral administration of clenbuterol twice a day.
• The administration began with the lowest dosage of 0.8 micrograms per kilogram.
• On the 10th day of treatment with the effective dose (determined from the range of 0.8, 1.6, 2.4, or 3.2 micrograms per kilogram), the treatment was either discontinued (Schedule A) or extended for an additional 20 days (Schedule B).

Results and Findings

• For the group of horses under Schedule A, significant improvements were observed on the 10th day of treatment in comparison to baseline, with a relapse after the treatment was discontinued.
• Horses under Schedule B demonstrated consistent improvements on the 10th, 20th, and 30th day of treatment, as compared to the baseline.
• An overall 75% of horses treated with incremental doses of clenbuterol showed clinical improvements. The lower bound of confidence interval was calculated to be 71%, signifying the reliability of the efficacy findings.
• However, 25% of horses did not respond to the treatment, emphasizing the variability in response among the subjects of the study.
• Horses with severe cases of COPD required higher doses of clenbuterol or were among the non-responders, as compared to horses with milder symptoms.

Side Effects and Safety

• The side effects of treatment included sweating, muscle tremors, and nervousness.
• However, these side effects were relatively minor (ranging from mild to moderate) and infrequent, occurring in less than 7% of all observations.
• The regimen of dosing clenbuterol incrementally to the horses contributed to the limited intensity and frequency of these side effects, demonstrating safety and tolerance of the drug for the majority of the horses.