How does a tablet work?

Single Dose

Some drugs, such as analgesics and hypnotics, may provide effective treatment following the administration of a single dose.

The graph below shows how the concentration of drug in the body or plasma changes over time. There is a short time when side effects are more likely to occur when the concentration of the drug in the body or plasma reaches a peak.

Multiple Dosages

As indicated in the graph below, some drugs, such as digoxin, need to be taken for a few days before a therapeutically effective concentration of drug in the body is achieved.

The graph shows how the concentration of drug in the body or plasma gradually builds up, peaking after each dosage, until it reaches a point at which it will be effective.

If drugs are taken more than once in a day then as well as patients being less likely to comply with their medication regimen, they will experience more 'peaks', increasing the risk of side effects.

The graph shows how the concentration of drug in the body or plasma varies when a drug is taken four times a day. There are four peaks following each dosage and these correspond to the times at which the patient is more likely to suffer side effects.

Extended Release Formulations

By giving drugs in extended release formulations ie once or twice a day, not only are patients more likely to comply with their medication regimen, but they are also less likely to suffer side effects.

The graph shows how the concentration of drug in the body or plasma varies for an extended release tablet taken once daily. It does not sharply peak but gradually increases and plateaus before gradually decreasing without reaching the point at which the patient is likely to suffer side effects.

 

Other links in this section:

• Information on tablet formulation.
  
  
• Tablet and capsule coatings and how they affect the action of the medicine.
  
  
• Clinical and legal reasons why tablet crushing and capsule opening should be avoided.
  
  
• Protocol providing guidance on medication administration for patients with swallowing difficulties (dysphagia), including those with percutaneous endoscopic gastronomy (PEG) and percutaneous endoscopic jejunostomy (PEJ) tubes in situ.
  
  
• Comprehensive list of liquid and non-oral alternatives to tablet and capsule formulations.

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