What Are Opioid Drugs?

Trying to relieve pain is one of the most important concerns of mankind. There are many medications that promise to relieve pain, but how many of them really work? In this article, we will explain what opioid drugs are and what they are used for.

What are opioid drugs?

Pure agonists

Opioid drugs that fall into the category of pure agonists bind directly to type µ receptors. Due to this interaction, side effects such as analgesia, euphoria, respiratory depression, constipation, nausea, vomiting and urinary retention are triggered.

Due to the many side effects that must occur to activate these receptors, the treatment of pain with these drugs is less common.

For example, morphine is a pure opioid agonist. The higher the dosage of this drug, the stronger the analgesic effect. However, morphine also produces a lot of side effects.

In addition, heroin is also a powerful analgesic. But due to the fact that it causes extreme dependence, most countries ban its use.

In short, pure agonists are opioid drugs that act as agonists and bind strongly to receptors. They are mainly used to treat certain types of pain, such as:

Mixed agonists-antagonists

This group of opioid drugs is not specific, which means that it can exert a partially agonist and antagonistic action. Mixed agonists-antagonists can interact with both µ and κ receptors.

Activation of κ receptors produces analgesic effects. However, the action is less potent than activating the µ receptors. In this case, the drugs provide the analgesic effect through the activity of both receptors.

Also, the set of effects that these drugs produce does not include respiratory depression. However, there are also a number of unwanted side effects, such as hallucinations, anxiety and vomiting, among others.

Also, mixed agonists-antagonists can cause addiction, but this is not as strong as that produced by pure agonists.

This group of opioids includes pentazocine, which has a moderate analgesic effect, three times weaker than morphine and nalbupin, among others. In general, the administration of these drugs is intended to treat moderate to severe pain.

Partial agonists

Pure antagonists

These drugs are opiates with affinity for opiate receptors, but with a lack of intrinsic activity. In addition, their affinity extends to the three main types of opioid receptors.

In this group, we find naloxone. Its main use is emergency medical treatment to reverse the effects of an opioid overdose, which can be life-threatening.

Naloxone can also be used after surgery to reverse the effects of opioids that are given during the procedure. Another use of naloxone is its injection into newborns to reduce the effects of opioids that the expectant mother receives before birth.