Which statement best describes dosing in obese animals?

Which statement best describes dosing in obese animals?

• A. Dose per kilogram should be higher than in normal-weight animals
• B. Dose per kilogram should be lower, based on weight halfway between normal and actual weight
• C. Dose per kilogram should be the same as in normal-weight animals
• D. Dose per kilogram should be based on ideal weight only

Answer: (B)

In obesity, drug dosing is often based on adjusted weight rather than total body weight. Fat tissue adds mass but contributes less to the pharmacologic effect and can alter how drugs distribute and are cleared. If you dose strictly by the actual weight, you risk overdosing many anesthetic drugs, especially those that are lipophilic. A practical approach is to use a weight between the ideal (lean) weight and the actual weight—as a rule of thumb, halfway between them. This adjusted weight accounts for the excess fat without pushing the dose up to the full actual body weight, providing a safer and more predictable balance between efficacy and safety. Using only ideal weight can underdose drugs that rely on distribution into lean tissues, while using actual weight can overestimate the needed amount; the halfway (adjusted) approach targets lean body mass to guide dosing.

In obesity, drug dosing is often based on adjusted weight rather than total body weight. Fat tissue adds mass but contributes less to the pharmacologic effect and can alter how drugs distribute and are cleared. If you dose strictly by the actual weight, you risk overdosing many anesthetic drugs, especially those that are lipophilic. A practical approach is to use a weight between the ideal (lean) weight and the actual weight—as a rule of thumb, halfway between them. This adjusted weight accounts for the excess fat without pushing the dose up to the full actual body weight, providing a safer and more predictable balance between efficacy and safety. Using only ideal weight can underdose drugs that rely on distribution into lean tissues, while using actual weight can overestimate the needed amount; the halfway (adjusted) approach targets lean body mass to guide dosing.