Opiates are a type of narcotic drug that are mainly used in the medication for pain. Their controversial use has lead to enforcement of strict drug control measures by various agencies. The mechanism of action of Opiates is simple.
Opiates act on a set of receptors present in the brain, spinal cord and other parts of the body. These receptors are divided into three varieties; mu, delta, and kappa. Some Opiates have a strong affinity to these receptors while others don’t.
On the basis of affinity for receptors, Opiates can be differentiated to weak and strong ones. This article elaborates on the different types of Opiates from weakest to strongest.
These receptors are divided into three varieties; mu, delta, and kappa. Some Opiates have a strong affinity to these receptors while others don’t. On the basis of affinity for receptors, Opiates can be differentiated to weak and strong ones. This article elaborates on the different types of Opiates from weakest to strongest.
Mechanism Of Action Of Opiates
Opiates are mainly used and prescribed by doctors due to their analgesic action. They do so by mimicking the action of endogenous opioid peptides by interacting with the Opiate receptors. These receptors; mu, delta, and kappa are coupled to the G1 proteins and this coupling makes the action of Opiates inhibitory in nature.
These receptors; mu, delta, and kappa are coupled to the G1 proteins and this coupling makes the action of Opiates inhibitory in nature.
The Opiates act by closing the N-type voltage-gated Calcium channels and open the Potassium channels to allow the influx of Potassium ions. As a result of this, the cells become hyperpolarized and thus there is a reduction in the excitability of neurons.
The Opiates act by closing the N-type voltage-gated Calcium channels and open the Potassium channels to allow the influx of Potassium ions. As a result of this, the cells become hyperpolarized and thus there is a reduction in the excitability of neurons.
Along with the above-mentioned mechanism, Opiates are responsible for decreasing the concentration of intracellular cAMP which is responsible for modulating the release of Substance P i.e. nociceptive neurotransmitter. In this way, Opiates achieve the action of analgesia.
The interaction between Opiates and opiate receptors occurs at various levels which include periaqueductal grey, the rostral ventral medulla, substantial nigra and the spinal dorsal horn. These areas of brain coordinate with other pathways and mechanisms to achieve one common goal i.e. analgesia.
Classification Of Opiates According To Nature
There are three types of Opiates according to their nature; the natural ones, synthetic ones and semi-synthetic ones!
Natural Opiates
Derived from the poppy plant they are considered less dangerous and harmful, yet they have high abuse and addiction potential. It can also cause severe respiratory depression in high doses. Following Opiates come in the category of Natural Opiates;
- Opium: also called Ope and Skee. It’s a schedule II drug that no more prescribed for pain. It is smoked.
- Morphine: Also called white stuff and monkey, it is a schedule II and III drug that is injected or used as a suppository to treat pain.
- Codeine: Cody comes in the category of Schedule II, III and IV drugs depending on its packaging. It is a constituent of cough syrups. It is swallowed or injected.
Synthetic Opiates
These types of Opiates are completely manmade. They have a chemical structure similar to the Natural Opiates. They are prepared in chemical laboratories. They cause effects similar to Natural Opiates.
- Methadone: The most commonly used synthetic opiate. It is a schedule II drug that is most often swallowed or injected. It is usually used to treat opioid addiction.
- Fentanyl: It is a schedule II drug that is available in sublingual tablet form and patch form. When abused it is snorted or smoked.
Semi-Synthetic Opiates
These types of Opiates are used as prescription narcotics and they are derived from natural opiates. Heroin, the most commonly used narcotic drug is derived from morphine.
- Heroin: It is a Schedule I drug that has no medicinal use. It usually injected but it can be snorted and smoked too.
- Meperidine: A schedule II drug that is also commonly abused.
- Oxycodone: Also called O.C, this is a schedule II drug and is used in the form of liquid and suppositories.
- Oxymorphone: Known as Blue Heaven, it is a schedule II drug that is taken orally.
- Hydrocodone: The trade name is Vicodin and it can be injected as well as swallowed.
- Hydromorphone: A schedule II drug that can be taken in the form of a suppository.
Classification Of Opiates According To Efficacy and Potency
What do we mean by potency and efficacy? These terms are used in pharmacology to define the strength and effectiveness of a drug. The potency of a drug is defined as the amount of drug necessary to produce maximum effects.
While Efficacy is the ability of a drug to elicit a response when it interacts with a receptor. Opiates with higher efficacy and potency are considered strong Opiates.
Opiates With Low Potency (Weak Opiates)
The Opiates which are considered weak have low potency and efficacy. They do not produce the desired effects. Their onset is slow and weak. The duration of action is short and the effects associated with Opiate intake are not fully achieved.
Codeine is considered to be the weakest form of Opiate. Hydrocodone also comes in the category of weak Opiates. Weak or mild Opiates are an agonist at mu receptors and have low analgesic efficacy. If they are used for relieving pain, they are used in conjunction with Ibuprofen and Acetaminophen.
If they are used for relieving pain, they are used in conjunction with Ibuprofen and Acetaminophen.
1. Codeine
It is the most constipating Opiate. It is a constituent of cough syrups and is commonly abused. Codeine is available over the counter but in some countries, you need a prescription for cough syrups too. It is the weakest form of Opiates and thus it has low abuse potential.
2. Hydrocodone
It is used in combination with aspirin and acetaminophen. It is highly addictive and should only be taken if a medical practitioner prescribes it.
3. OxyCodone
It has a potency similar to that of Morphine but it has relatively fewer side effects. It has sustained release and therefore it can be used in higher doses. Side effects of morphine related to the gastrointestinal and CNS systems are more as compared to that of OxyCodone.
4. Oxycontin
It is a relatively weaker Opiate.
Highly Potent Types Of Opiates (Strong Opiates)
Opiates that are a full agonist at the mu receptors and show high efficacy and potency are labeled as strong Opiates. This list contains Methadone, Fentanyl, and Morphine. These are mainly used in moderate to severe chronic pain and for relieving post-surgical pain.
1. Fentanyl
It can be administered in various ways. The most common way is to use transdermal patches. Transmucosal preparations are also used. Parenteral mode of administration proves to be short-acting. Round the clock administration of Fentanyl is necessary as it short-acting in nature. It is given during and after surgeries to relieve the pain of surgery.
2. Methadone
The main use of Methadone is to reduce withdrawal symptoms in those persons who are addicted to narcotics like heroin. It is one of the strongest prescription opiates that are used in a prescription for post-operation pain.
It is abused by people due to its strength. It is considered more effective than other opiates for relieving neuropathic pain because it also has NMDA receptor activity.
However, it is a difficult drug to manage as it has a very slow onset of action and the duration of action is extended.
The active metabolites of Methadone have long half-lives and its accumulation may result in difficulty in breathing, prolonged sedation.
3. Hydromorphone
Its pharmacology resembles morphine as it is effective orally and relieves pain with the same efficacy. It forms a part of the treatment regimen of idiosyncratic reactions.
4. Oxymorphone
It is also considered a potent strain of Opiates and has high analgesic action thus it is also used for chronic pain.
5. Morphine
It is 80 to 100 times less potent than Fentanyl. It is highly effective in relieving pain. The metabolites generated after the metabolism of Morphine do not accumulate. It is effective orally but it can be administered via other routes too.
User Reviews
According to user reviews on various drug forums, Oral Oxymorphone is the strongest Opiate considering the ‘high-effect’. Next, comes oral morphine, then poppy tea, then IV Morphine, Hydromorphone, smoked fentanyl, IV Oxymorphone, then IV Oxycodone, then Oral Oxycodone and lastly snorted Heroin.
For pain the strongest Opiate is morphine, then hydrocodone, then fentanyl and lastly heroin.
Considering the above-mentioned review, it is noticeable that the route of administration is important when labeling an Opiate strong or weak. Some Opiates show more potency when taken intravenously, while others show more efficacies when taken orally or snorted. Any sort of adjuvant and additives can also alter the potency of Opiates.
Some Opiates show more potency when taken intravenously, while others show more efficacies when taken orally or snorted. Any sort of adjuvant and additives can also alter the potency of Opiates.