Competitive Antagonists

What is a competitive antagonist?

A competitive antagonist is a drug or chemical which binds to a specific receptor site and once there, blocks another drug or chemical from binding to that site. While the competitive antagonist binds to a particular drug receptor site, another drug must compete to gain access to that receptor. Normally, if both drugs have the same affinity (conectivity and likeness) for the receptor, then the only way they can compete with each other is by having more drugs.

For example,

Naloxone is a competitive antagonist that competes for the opioid receptor sites within the body. This has the medical significance, that any patient who has had either an opioid overdose (as a result of excessive opioid analgesia) or heroin overdose – a doctor, nurse or paramedic may administer naloxone and it will compete as an antagonist with the opioids already in the body for a spot on the opioid receptors, but it will not cause any affect on the opioid receptors