How drugs work

BiochemistryPrinciples of Pharmacology

How drugs work

1How drugs workThis presentation explains how drugs work

Most drugs act at a molecular level where they mostly bind to proteins to produce their therapeutic effect

2How drugs work part IMost drugs bind to proteinsThere are thousands of different proteins in the bodyPerforming thousands of different tasksThus there are potentially thousands of different targets for drugs3Types of proteinThere are four classes of protein that are targeted by drugs receptors enzymes ion channels carrier proteins4Receptor proteinsReceptors are found on every cell in the bodyReceptors are very popular targets for drugsDrugs that bind to receptors include Beta blockers Salbutamol Morphine5Agonists and antagonistsSome drugs bind to receptors and produce the same effect as the endogenous ligandThese are called AGONISTSSome drugs bind to receptors and produce no effect other than preventing the endogenous ligand from bindingThese are called ANTAGONISTS6Agonists and antagonists

7Cell membrane interactions

EnzymesEnzymes are complex proteins that take part in biochemical reactionsMany drugs target enzymes and block biochemical reactionsEnzyme targeting drugs include ACE inhibitors NSAIDs Statins9How drugs act on enzymes

10Ion channelsIon channels allow ions to cross membranesNeurological functions rely on ion channelsMany drugs block ion channels including Local anaesthetics Anti-arrhythmics Benzodiazepines11Channel blocking drugs

12Carrier proteinsCarrier proteins actively transport molecules across membranesThey are popular targets for drugs including SSRIs (prozac etc.) Tricyclic antidepressants Loop diuretics13Drugs acting on carrier proteins

14Similar chemical structure leads to similar functionDrugs work by mimicking the chemical structure of a desired target molecule

Damaged and pain-causing cells produce large quantities of an enzyme called cylooxygenase-2. This enzyme in turn produces a chemical called prostaglandin, which sends a message to the brain signaling that a specific part of the body is in pain. The chemical also causes the injured area to release fluids, causing it to swell or become inflamed. ASA (Aspirin) adheres to the cylooxygenase-2 and prevents it from producing prostaglandin. Acetaminophen and ibuprofin also work as an antagonist blocking the production of prostaglandins. As a result, some of the pain signals do not reach the brain and less pain is felt. Also, the inflammation is minimized due to the lack of prostaglandin production.

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Acetylsalicylic acid ASA AspirinCaffeine 1,3,7-trimethylxanthine, to give it its chemical name is a member of a group of naturally occurring substances called methylxanthines.These compounds are similar in structure to adenosines, naturally occurring molecules in our bodies which aid the onset of sleep. In its natural context, which is in tea and coffee plants, caffeine can kill or paralyse insects and is thus an effective natural pesticide.Adenosine bonds to receptor cells in the brain to calm the activity of the central nervous system, thus triggering tiredness. There is also evidence to suggest that it decreases blood flow in the brain. Caffeine molecules bind to these receptor cells but have no active effect on the nervous system. However by doing so they take the place of adenosine molecules that could make a difference. This process is known as "competitive inhibition" and effectively delays the onset of fatigue, increases alertness and improves people's ability to sustain attention. Agonist or Antagonist?

Due to the similarity in structure, the caffeine molecule can bind to receptor proteins that would normally bind to an adenosine derived molecule. These receptors produce chemicals which tell an organism it is tired and needs to sleep.

Benzodiazepine receptors are also affected by caffeine, these receptors control feelings of panic and anxiety in humans.