Pharmaceutical products and drug action – IB Chemistry Higher Level Revision

Pharmaceutical products are developed to treat, cure or prevent diseases.
Drugs act by interacting with biological targets in the body.
Most drugs are small organic molecules, although some are larger biological molecules.

Drug development is a long and complex process that often takes 10-15 years.
It begins with drug discovery, which can involve natural products, high-throughput screening, or rational drug design.
Once a potential drug is identified, it undergoes pre-clinical studies in the laboratory and in animals to assess safety and efficacy.
Drugs that pass pre-clinical studies undergo clinical trials in humans. This process is split into Phase I, II, III and IV trials, each with different goals and scales.
Only drugs that are found to be safe and effective in clinical trials are approved for use.

Drugs can exert their effects by binding to a variety of molecular targets, including enzymes, receptors, and ion channels.
The majority of drugs work by acting as agonists (activating their target) or antagonists (inhibiting their target).
An important factor determining the effectiveness of a drug is the strength of its binding to its target, known as its affinity.
Another important factor is the drug’s selectivity, or its ability to bind to its intended target without interacting with other molecules in the body.
Finally, a drug’s efficacy, or the degree to which it activates its target, is also crucial in determining its therapeutic effect.

Most drugs can cause unwanted side effects, which can range from minor to severe.
Side effects usually result from the drug interacting with molecules other than its intended target(s), but can also result from overdosing.
The therapeutic index, or the ratio of the dose that causes therapeutic effects to the dose that causes toxicity, is an important measure of a drug’s safety.
Drugs with a high therapeutic index are generally safer than those with a low index, as they can be used at higher doses without causing toxicity.

After administration, drugs are typically absorbed into the bloodstream and distributed throughout the body.
They are then metabolised by enzymes in the liver and other tissues, and the resulting metabolites are usually less active and more water-soluble.
Most drugs and their metabolites are eliminated from the body in the urine, although some are excreted in the faeces, sweat, or exhaled air.
It’s important to remember that interactions with other drugs, as well as individual variability in metabolism and excretion, can greatly affect a drug’s effectiveness and safety.