PTCB Guide to Opioid Analgesics!

PTCB Guide to Opioids

Opioids are among the most widely dispensed medicines in the United States. Here in this PTCB guide to opioids, we review the must-know facts you need to study.

In 2020, there were over 142 million prescriptions for opioids. Pharmacy technicians are expected, then, to have a thorough and robust understanding of this drug class – what they are used for, how they work, as well as major side effects and drug interactions. Technicians are also expected to know brand names, too.

Though 142 million prescriptions were dispensed, the trend for opioid prescriptions is in decline. It reached a peak in 2012, when there were over 255 million prescriptions. However, it’s worth noting that dispensing rates vary widely across different states and counties.

Given the rate at which opioids are dispensed, it is likely you will regularly come across prescriptions that contain opioids.

Opioids are, of course, used primarily to treat mild-to-moderate pain, or moderate-to-severe pain – depending on the opioid.

They are classified as Schedule II/IIN Controlled Substances (2/2N).

Weak to Intermediate Opioids	Strong Opioids
Codeine	Morphine
Dihydrocodeine	Oxycodone
Hydrocodone	Fentanyl
Tramadol	Pethidine
Buprenorphine	Methadone

Though opioids are traditionally used for analgesia (pain relief), they are also used in the context of end-of-life care, where they can be used to relieve breathlessness.

Mechanism of Action

Analgesic opioids work by targeting and activating mu receptors.

Mu receptors can be found in the central nervous system (CNS). By activating these receptors, opioid analgesics reduce nerve excitability and pain transmission signals.

Opioids also work in the medulla to reduce respiratory (breathing) rate and breathlessness. The medulla is the bottom-most part of the brain responsible for vital processes such as:

• heart rate
• breathing
• blood pressure

Through the same mechanism, opioid analgesics can reduce anxiety associated with breathlessness.

Side Effects

Side effects of opioids, like all medicines, is linked to the mechanism of action and other effects that opioids have on other receptors in the body. That’s because there is more than one type of opioid receptor. The mu receptor is simple the one opioid receptor primarily responsible for analgesia.

Other opioid receptors include delta, kappa, and zeta. You’ll note how opioid receptors in the body take their names from the Greek alphabet.

Opioids are therefore associated with a wide range of side effects, including:

• respiratory depression – slower, shallower breaths where the lungs can fail to exchange carbon dioxide and oxygen efficiency.
• constipation – one of the most common side effects of opioids.
• euphoria – an intense feeling of happiness or excitement.
• nausea and vomiting
• pupillary constriction
• itchy skin – because opioids can trigger histamine release

Due to the mechanism and the ability to cause euphoria, opioids can become addictive.

Consistent use of opioids can lead to tolerance – where the dose must be increased to achieve the same euphoric effect; and dependence – where abrupt cessation of taking opioids can cause a withdrawal reaction.

For these reasons, opioid abuse in the wider population continues to remain a public health challenge.

According to the HHS, “In 2019, an estimated 10.1 million people aged 12 or older misused opioids in the past year. Specifically, 9.7 million people misused prescription pain relievers”.

Drug Interactions

A general principle in pharmacy is that drugs that cause sedation, like opioids, should not be taken with other drugs that cause sedation. For example:

• antipsychotic drugs
• tricyclic antidepressants
• benzodiazepines

The same principle applies with alcohol, as this too can cause respiratory depression and sedation. Taking opioid analgesics with this category of CNS altering drugs / alcohol is therefore dangerous and should be avoided.

However, there are clinical circumstances where it may be unavoidable for a patient to take an opioid and an antipsychotic drug, for example. It may be deemed clinically necessary by the healthcare provider. In these cases, close monitoring of the patient is required.

Take Home Message

That concludes our rapid revision PTCB guide to opioids.

Over the course of this article, you have learned:

• Opioids are among the most widely prescribed drugs in the United States.
• Opioids are used as analgesics; to reduce pain.
• Weak opioids include codeine, dihydrocodeine, and tramadol; whereas strong opioids include morphine, methadone, fentanyl, and oxycodone.
• Opioids work by activating mu-opioid receptors in the CNS.
• Opioid side effects include respiratory depression, itch, constipation, euphoria, and pupillary constriction.
• Opioids should be avoided with other sedating drugs due to their combined sedative effects.
• Opioids can cause tolerance and dependence with regular use. Withdrawal reactions are likely.

If you have found this PTCB guide to opioids helpful and would like access to even more exclusive features to help you pass the pharmacy technician exam, learn more about our self-paced online course that guarantees your exam success.