General
Opioid analgesics are the mainstay of pain treatment for cancer patients
for whom tumor treatment has failed. Highly successful treatment of
nociceptive or somatic pain is possible with the opioid analgesic drugs
currently available. These drugs are less successful in treating
neuropathic pain. This distinction is important because in the former
situation, when opioids are used, no ceiling effect will limit the dose
required to provide relief, whereas in the latter situation, escalating
the dose after some relief has been obtained may cause undesirable
side-effects rather than additional pain relief.
Attitudes of health care providers are perhaps the most influential force
in determining whether a cancer patient in pain is adequately relieved of
his or her pain. Cultural forces almost universally influence the
physician to perceive a patient as a substance abuser who makes atypical
claims about their pain experience or about his or her response to
treatment. The patientıs report of pain must be believed!
Physicians are also influenced by the prescribing practices of their peers
to the extent that pharmacological knowledge is subordinated to the
practice customary in the community; i.e., if customary prescribing
results in under treatment, but is the community standard, it is likely
physicians will adopt the community standard making under treatment of
pain the norm. If adequate pain treatment is to be the norm, this vicious
cycle must be broken. Proper pharmacological prescribing must replace
customary prescribing. In customary prescribing outcome is ignored.
Information about dosing for opioid drugs contained in standard
pharmacological textbooks was obtained primarily from studies of single
doses of opioids given to patients who had post-operative pain. No
long-term studies of the use of opioids were done. Consequently,
information about dosing is limited to this population of patients. The
pharmacodynamic (what the drugs do to the body) effects where studied in
addict volunteers at federal penal institutions. None of the subjects had
pain. Such studies would be analogist to studying insulin requirements and
metabolism in subjects who did not have diabetes. New studies on pain
patients, such as cancer patients, taking opioids long-term for pain
reveal that significant differences between knowledge gained in the old
studies and knowledge gain in the new studies. This difference shows up
in critical areas: 1 ) pain is a natural antagonist to the analagesic
effect of opioids making it necessary to provide a dose of analgesic that
will overcome this antagonism. This is the rationale for, the proper dose
is whatever it takes to relieve the pain, as the dictum for guiding
prescribing analgesic drugs. 2) pain is also a natural antagonist to
respiratory depression. Therefore, respiratory depression in pain
patients is extremely rare, no matter what the dose of opioid required for
the relief of pain. This is especially true in patients who have been
taking opioids over a significant time period and are tolerant to opioids,
and 3) psychological dependence (addiction) in cancer patients in pain who
have no previous history of drug abuse rarely become psychologically
dependent on opioids given for pain.
The facts about biotransformation of drugs (pharmacokinetics - what the
body does to the drug before it gets to the site of action of the drug)
are often not known, misunderstood, or ignored in prescribing opioids.
Therefore, equianalgesic doses between oral and parenteral opioids are not
prescribed. Oral medication is subject to the "first pass effect" as the
absorbed dose is reduced by its first pass through the liver, whereas
parenteral medication is delivered to the central nervous system without
this reduction. Oral doses must be adjusted upward to compensate for this
reduction in the quantity delivered to the opioid binding sites. The
perception that oral doses are larger than parenteral doses is merely an
illusion.
Certain drugs used to treat pain and side-effects of these drugs are
scheduled under both the federal and State of Texas Controlled Substance
Acts. This means their use is monitored and scrutinized by government
agencies responsible for monitoring these drugs, more closely than
non-scheduled drugs to prevent diversion to illegal use. Unfortunately,
there is no common understanding between these agencies and physicians
about what the standard of practice is for their use. This confusion makes
physicians reluctant to prescribe them and accounts for one of the major
reasons patients get inadequate treatment of their pain.
Texas has made significant strides since 1989 to clarify the confusion
about using opioids, and other controlled substances, for pain treatment
and encouraging their use. In 1989 the legislature passed the Intractable
Pain Treatment Act (IPTA) (Article 4495c V.T.C.A.). The major features of
the Act are: 1) defines intractable pain, 2) permits the physician to
prescribe controlled substances after he/she makes a diagnosis of
intractable pain without regard to the etiology of the pain (malignant or
benign), 3) prohibits a hospital or other health care facility from
interfering with a physicianıs prescribing these drugs for an
appropriately diagnosed intractable pain condition, and 4) prohibits the
Texas State Board of Medical Examiners from imposing sanctions on
physicians who prescribe these drugs to treat intractable pain. In 1997
this Act was amended to permit the prescribing of opioids to current
substance abusers (addicts) or individuals who have a history of drug
abuse who develop acute or chronic painful medical conditions. Two major
categories of diseases where this situation may occur are cancer and AIDS
patients. (See Appendix D, The Intractable Pain Treatment Act and its
amendment, page --)
To further clarify the standards of practice for the use of Schedule II
drugs for pain treatment, the Texas State Board of Medical Examiners
(board) adopted rules in 1995 regarding their use. The significance of the
board adopting rules is that rules have the same force as law. . An
oversimplification of them is that any use of them is permissible so long
as they are prescribed for a legitimate medical purpose during the usual
course of medical practice and there is adequate documentation of the
rationale for their use. (See Appendix E, Chapter 170. Authority of
Physician to Prescribe for the Treatment of Pain, page --)
