Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that your little one ingested a 2.5mg ramipril tablet. This is an angiotensin converting enzyme inhibitor that can be used in cats to control hypertension, heart disease and protein loss in diseased kidneys.
It is quickly absorbed and the maximum ramipril concentrations were seen within 30 minutes following a single dose. The blood levels decreased rapidly, within 4 hours they were below appropriate levels. But the drug does linger in their system, with a terminal half-life greater than or equal to 20 hours no matter what dose is given. The drug is primarily excreted through the feces and urine.
Angiotensin converting enzyme activity was almost completely gone within 2 hours after treatment, no matter how high the dose. Significant inhibition of angiotensin enzyme activity was still present 24 h after treatment. That means that the effects of the drug do linger for at least 24 hours. At appropriate doses treatment was well-tolerated in all cats.
Ramipril is given at a dose rate of 0.125 mg/kg once daily produces significant and long-lasting inhibition of ACE activity in healthy cats.
If your girl ingested 2.5mgs then if she weighs 20kgs this would be an appropriate dose. Of course I highly doubt that she weighs this much. That means that she has taken a significantly higher dose than usual and the drug will linger in her body for at least 24 hours, so we would expect to see some effects from the drug for at least 24 hours. Although drugs in this class are fairly well tolerated, and one time doses as high as 1mg per kilogram of body weight caused no long term harm I am a bit concerned, especially if she is less than 2kgs.
We can see reduced blood pressure, which can show itself via symptoms of poor exercise tolerance, sleepiness, lethargy or incoordination.
If she weighs 3kgs or more and she is behaving normally and is otherwise healthy you can take a watch and see approach over the next 24 hours. If she is weak, very sleepy, her gums are pale in color or she is uncoordinated then she should be seen on an emergency basis for fluids and medications to raise her blood pressure.
Please let me know if you have any further questions.