How does weight affect drug metabolism?

How does weight affect drug effectiveness?

Changes in body weight can influence the amount of medicine you need to take and how long it stays in your body. The circulatory system may slow down, which can affect how fast drugs get to the liver and kidneys.

Does body size affect drug metabolism?

The main factors that affect the tissue distribution of drugs are body composition, regional blood flow and the affinity of the drug for plasma proteins and/or tissue components. Obese people have larger absolute lean body masses as well as fat masses than non-obese individuals of the same age, gender and height.

How does obesity affect drug metabolism?

In general, studies have shown that clearance of renally eliminated drugs is higher in obese patients. This increase in CL is likely due to increased glomerular filtration and tubular secretion.

How does weight affect pharmacokinetics?

Effect on distribution:

Increased volume of distribution for lipid-soluble drugs. Increased accumulation of drugs in the fat compartment. Blood flow in fat is poor in people of normal weight: it is only about 5% of the total cardiac output. In obese individuals, blood flow to fat is even poorer.

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Does medicine go by weight or age?

If you (or the child you are giving a medicine to) weighs less than 95 pounds and is using a children’s (or infant’s) medicine where the dose is chosen by weight and age, it is better to choose the medicine dose by weight.

Does Weight Affect ibuprofen?

Ibuprofen volume of distribution was increased in obese subjects, and this increased distribution correlated positively with body weight (r = 0.82; P less than 0.001).

What is total body weight?

Total body weight (TBW) = Patient weight (kg). … Despite its ease of measurement, there are a few disadvantages of using a patient’s TBW on admission to Critical Care. Patients often have received large volumes of resuscitation fluid prior to admission, thus TBW may not reflect the patient’s pre-hospital ‘normal’ TBW.

How does age affect drugs in the body?

In general, as we age, total body water and muscle mass decrease while percentage of body fat increases. These changes can lead to drugs having a longer duration of action and increased effect. Drugs that were effective may become compounded and overexceed their therapeutic threshhold causing increased side effects.

What happens when an obese person is given with a lipophilic drug?

Oral drug absorption is not altered by obesity. Lipophilic drugs may take longer to reach steady state than hydrophilic ones as there is increased fat mass, taking these drugs longer to saturate the fat compartment. Subcutaneous and intramuscular routes of administration may have an unpredictable effect in the obese.

What is an ideal body weight?

According to the National Institutes of Health (NIH): A BMI of less than 18.5 means that a person is underweight. A BMI of between 18.5 and 24.9 is ideal. A BMI of between 25 and 29.9 is overweight.

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Does volume of distribution change with weight?

For convenience, the volume of distribution is usually normalized to body weight because it is reasonable to expect that the volume of distribution will increase with body weight. … Drugs that are more extensively bound to tissues than to plasma proteins have volumes of distribution greater than 700 ml/kg of body weight.

Is succinylcholine lipophilic?

Non-depolarizing neuromuscular blocking agents can be dosed in this manner. Succinylcholine is an exception, dosage should be calculated using TBW. The majority of anaesthetic drugs are strongly lipophilic.

Is BMI an accurate indicator and diagnostic tool of body fat?

BMI (your weight in kilograms divided by the square of your height in meters) is a pretty reliable way to determine whether you have too much body fat. That said, BMI is not a perfect measure because it does not directly assess body fat.

Is Propofol lipophilic?

Propofol (Diprivan) is a phenolic derivative with sedative and hypnotic properties but is unrelated to other sedative/hypnotic agents. Formulated as an oil-in-water emulsion for intravenous use, it is highly lipophilic and rapidly crosses the blood-brain barrier resulting in a rapid onset of action.

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