How long does it take phenobarbital to get into the system of a dog?

The time it takes for phenobarbital to get into the system of a dog depends on several factors, including dosage, method of administration, the dog's weight and health status. Here are some general guidelines:

Oral administration: When given orally, phenobarbital typically takes 30-60 minutes to reach its peak concentration in the bloodstream. It can take up to 2-4 hours for the medication to reach steady state levels in the body.

Intravenous administration: When given intravenously (IV), phenobarbital reaches its peak concentration in the bloodstream within a few minutes. The effects of the medication can be seen almost immediately.

The onset of action, which refers to the time it takes for the drug to produce a noticeable effect, is usually within 30 minutes to an hour for both oral and IV administration. However, the full therapeutic effects of phenobarbital may take several days to weeks to become fully apparent.

Factors such as the dog's liver and kidney function, age, and any concurrent medical conditions can affect how the drug is metabolized and eliminated from the body. If you have any concerns about how long it takes for phenobarbital to reach its full effect in your dog, consult with your veterinarian.