- All pains respond to a high enough dose of opiates
Although opiates are by far the most effective group of analgesics, many times they fail to provide relief, either due to the pathology or because of individual variations. Neuropathic pain, especially those secondary to spinal cord injuries, are notoriously poor responders to even high doses of opiates.
- Codeine is weaker than morphine
Codeine has no analgesic properties by itself; it becomes an analgesic only after the liver transforms it into morphine. In fact most of the codeine in the US is manufactured from morphine, a much more abundant chemical in poppy than codeine.
- Propoxyphene is a safer opiate for older folks.
An analogue of methadone, propoxyphene is a weaker form of opiate. It is, however, metabolized to norpropoxyphene, which tends to accumulate in the organism of older individuals, possibly leading to confusion and falls. The same phenomenon occurs with meperidine administration, leading to the accumulation of normeperidine, a powerful central nervous system stimulant and a frequent cause of iatrogenic seizures. The toxicity of both drugs increases dramatically in cases of renal insufficiency.
- Addicts shouldn't receive opiates
A patient undergoing a surgical procedure, such as a knee replacement, should be offered the option of receiving opiate analgesics post-operatively, whether they present with a history of addiction or not. The choices for analgesia should be thoroughly discussed with the patient, including alternatives to the use of opiates, such as epidural catheters etc. Good sense should prevail as to the duration of treatment.
The treatment of addicts with chronic pain presents as a much bigger challenge and should be reserved to a pain specialist
- Methadone is the drug of choice for many addicts
Not really. Methadone is not known to provide the quality of "high" that many other opiates do. The drug is used by addicts primarily to avoid withdrawal when the other drugs of choice, such as heroin, are not immediately available. It would seem, therefore, that methadone would be a good choice for the treatment of pain in patients predisposed to drug abuse. In reality, methadone can be diverted, and readily exchanged on the street for the addict's drug of choice.
- The amount of opiates required for analgesia invariably increases
The majority of patients with a stable painful medical condition can maintain the same level of analgesia for many years, on an unchanging dose of opiates. The most common reason for increased opiate requirement is progression of the disease, such as seen in rheumatoid arthritis and cancer.
When tolerance to the analgesic effect of an opiate does develop, substitution for a different class of opiate, in equianalgesic doses, is often quite effective.
- There is no ceiling to the dose of opiates in the treatment of severe pain
If we put aside the risk of respiratory depression, opiates are among the safest drugs known to man. This inherent safety, coupled with the fact that some patients do respond well to very high doses of opiates, led to the notion that the dose of analgesics should be limited only by the experience of the prescribing physician.
Alas, not so. Opiates do induce changes in the central nervous system including personality alterations, hormonal depletion, and myoclonic activity. More seriously, high dose opiates may lead to a paradoxical, generalized, and intractable pain, a state of hyperalgesia, which can only be helped by the reduction or withdrawal from opiates. Although not immediately apparent in the early stages, hyperalgesia is manifested by a progressive spread of the pain to previously unaffected areas, and in parallel with the gradual increase in the prescribed dose of analgesic.
© Dr. Moacir Schnapp and Dr. Kit Mays
Tell Me Where It Hurts
Pain As A Neurodegenerative Disorder
The Multidisciplinary Approach to Pain
Pain is Obligatory, But Suffering is Optional
Pain: Myth Busters
Sleepless in Pain
The Pain from Shingles
When You Need a Pain Specialist
Why Does Pain Hurt?