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The mechanism of action is a crucial factor in determining effect and toxicity of the drug, taking in consideration the pharmacokinetic (PK) factors. [12] The sort and extent of altered cellular physiology will depend on the combination of the drug's presence (as established by pharmacokinetic (PK) studies) and/or its mechanism and duration of ...
This suggests a significant genetic factor in the likelihood of later hard drug usage. The study suggested that a causal role of cannabis use in later hard drug usage is minimal, if it exists at all, and that cannabis use and hard drug use share the same influencing factors such as genetics and environment. [51] [50]
The action of drugs on the human body (or any other organism's body) is called pharmacodynamics, and the body's response to drugs is called pharmacokinetics. The drugs that enter an individual tend to stimulate certain receptors, ion channels, act on enzymes or transport proteins. As a result, they cause the human body to react in a specific way.
An example of a drug where first-pass metabolism is a complication and disadvantage is in the antiviral drug remdesivir. Remdesivir cannot be administered orally because the entire dose would be trapped in the liver with little achieving systemic circulation or reaching target organs and cells (for example, cells infected with SARS-CoV-2).
If a drug can bind to unexpected proteins, receptors, or enzymes that can alter different pathways other than those desired for treatment, severe downstream effects can develop. An example of this is the drug eplerenone (aldosterone receptor antagonist), which should increase aldosterone levels, but has shown to produce atrophy of the prostate. [3]
A drug's removal rate will be determined by the proportion of the drug that is removed from circulation by each organ once the drug has been delivered to the organ by the circulating blood supply. [1] This new concept builds on earlier ideas and it depends on a number of distinct factors: The drugs characteristics, including its pKa.
When designing drugs, the placebo effect must be considered to assess the drug's true therapeutic value. Drug development uses techniques from medicinal chemistry to chemically design drugs. This overlaps with the biological approach of finding targets and physiological effects.
A few drugs such as alcohol are absorbed by the lining of the stomach, and therefore tend to take effect much more quickly than the vast majority of oral medications which are absorbed in the small intestine. Gastric emptying time can vary from 0 to 3 hours, [2] and therefore plays a major role in onset of action for orally administered drugs ...