PAIN THERAPY

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PAIN THERAPY

Post  counselor on Mon Oct 15, 2012 11:49 am

PAIN THERAPY


In 1990 an article in the scientific community Melzack emphasizes the lack of attention paid to common pain therapy and the need to properly treat pain syndromes (Melzack R: The tragedy of needless pain, Sci Am 262: 27-33, 1990

In a 2002 issue of the Bulletin of Information on Drugs AIFA (a. VIII, n. 2, 2002) reports that:
• Clinical practice continues to be characterized by pain not removed
• Yet, surgical pain, post-operative or invasive diagnosis can be well controlled.
• The pain of terminally ill patients can be relieved with pharmacological treatments
• Neurogenic pain is resistant to opioid analgesics, but is reduced by other drugs
• The patient does not have to live with the pain that can be removed.

• In the past it was correct not to take action on certain types of pain because the evolution of that was useful for diagnosis. Today, the modern instrumental methods of diagnosis mean that it is no longer necessary to use pain as a diagnostic tool,
• The culture of suffering as a means of atonement must be overcome
• Dose and duration of analgesic treatment should be defined on the basis of the patient's pain, not regulations or protocols.
OPPIOFOBIA

But the strongest affirmation is that, for an effective pain control, must be exceeded OPPIOFOBIA existing.

The International Association for Hospice and Palliative Care complains that there is oppiofobia both in patients and health professionals.

The oppiofobia the patient is due to:

• belief that if you take morphine because death is drawing near
• fear that it is not much if the pain gets worse
• fear of becoming addicted
• fear of not tolerate side effects


The oppiofobia of health personnel is due to:

• Fear of addiction
• fear of tolerance and physical dependence
• fear of other side effects
• Fear of respiratory depression especially
• legislative issues (In Italy, the DPR 309/90 regarding the use of opioid analgesics has been considered as one of the biggest causes of oppiofobia)



ADDICTION

The pain contrasts strongly istaurarsi drug addiction

For the treatment of pain, we recommend the use of morphine and other opioid drugs orally. Oral administration does not give rise to the rewarding effects of reinforcement and sensitive.

Even if the subject develops tolerance and physical dependence during a therapy, it rarely becomes a drug addict.

The incidence of drug dependence is less than 1%, as reported in numerous articles:

1. Porter J, Jick H. Addiction rare in patients treated with narcotics. N Engl J Med 302:123; 1980
2. Wycross RG. Clinical experience with diamorphine in advanced malignant disease. Int J Clin Pharmacol 7: 184-198, 1974.
3. Kanner RM, Foley KM. Patterns of narcotic drug use in a cancer pain clinic. Ann NY Acad Sci 362: 161-172; 1981.
4. Mercadante S. Diarrhea, malabsorption and constipation. In: Berger AM, Partenoy RK, Weissman DE. Philadelphia: Lippincott-Raven, 1998, 191-205.




TOLERANCE

• In chronic cancer pain is not common to see strong development of tolerance
• In general, the increase in dose dependent by the increasing disease.
• It is recommended not to insufficient treatment for fear of tolerance!!


PHYSICAL DEPENDENCE

• The dependence tends to istaurarsi at higher doses than those that damage tolerance.
• Pain in sharp contrast to the istaurarsi of physical dependence
• The use of an opioid drug at regular time intervals (as recommended in the treatment of pain) determines blood levels of medication lower, reducing the risk of dependence



RECOMMENDATIONS OF THE WORLD HEALTH ORGANIZATION '

Already in 1986, the WHO has given very specific suggestions for the treatment of chronic pain of cancer




Drug treatment should be:

1. by mouth (orally)

2. by the clock (at regular intervals)

3. by the ladder (according to the "ladder")


Oral administration of drug produces:
• Blood levels are lower
• less rewarding and reinforcing effects
• fewer side effects


The administration at regular intervals:
• requires fewer doses than when the use of morphine is done when needed
• generates constant levels of morphine-6-glucuronide


The ladder (the ladder) is to indicate that the type of drug to be administered depends on the intensity of the pain. On a scale of increasing pain it is recommended to use:
• non-opioid analgesics (NSAIDs and coxib)
• Opioids weak
• Opioids strong

The intensity of the pain must be declared by the patient by reference to measurement scales, such as those noted below.


Non-opioid analgesics are recommended for mild pain
(Intensity 1 to 4)

Weak opioids are recommended for mild to moderate pain
(Between 5 and 6)

Strong opioids are recommended for severe pain
(Between 7 and 10)

At each stage, the treatment may be supplemented with co-analgesics or adjuvants to enhance analgesia and to reduce side effects.


MEASURING INTENSITY 'PAIN

• Give credit to what the patient reports
• The patient must indicate the intensity of pain with appropriate scales
• You must inform the patient but also on the side effects of drugs and explain that if you use too much medication can have many side effects
• Post-operative pain and exacerbations of cancer require evaluation at short intervals (1 or more hours).
• For chronic pain just once every 24 hours.
• Ensure site, type of pain and triggers

With regard to etiology, we can distinguish the pain:
Nociceptive or physiological
Due to stimulation of afferent nociceptive sensors for tissue insult

Neuropathic pain
Due to nerve damage (diabetic neuropathy, neuralgia trigemico, post-herpetic neuralgia, pain from stroke)

Pain from damage of the sympathetic nerves
Due to vasomotor instability. Does not respond well to analgesics, but regional nerve block

Psychogenic pain
There is a physical basis




PHARMACOLOGICAL TREATMENT

• Select the type of drug for pain
• Follow the "analgesic ladder"
• "owner" of the dose in relation to the needs of the patient
• Administer at regular intervals, preferably orally
• Provide information to the patient
• Dealing with side effects
• Use adjuvant medications




Non-narcotic analgesics

It is recommended for use in mild-moderate pain

Respond best:
• mild pain somatic (headache,
myalgia, dysmenorrhea)
• pain from inflammation,
• pain in the bones,
• post-operative pain

They are widely used paracetamol, diclofenac, propionic acid derivatives, COX2 selective inhibitors.

The choice of single drug depends on:
• The effectiveness and
• tolerability of side effects

-L'ibuprofene has the lowest GI risk
COX2-selective inhibitors have low GI risk
-Piroxicam, indomethacin, ketoprofen, diclofenac,
naproxen intermediate risk

Combination therapy

The non-narcotic analgesics may be administered together with opioid analgesics for pain moderate and severe, in order to obtain:
-Summation of the analgesic effects of a different nature
-Better analgesic efficacy
-Fewer side effects

Opioid analgesics

Are weak opioids:
• Codeine
• Dihydrocodeine
• Tramadol
• Dextropropoxyphene

Are strong opioids
• Morphine
• Diamorphine
• Hydromorphone
• Methadone
• Oxycodone
• Fentanyl and alfentanyl
• Buprenorphine (MOP partial agonist)


Morphine
Morphine is the drug of choice among strong opioid narcotic analgesic and is the first line for the treatment of moderate to severe pain.

In the initial phase of "dose titration" are used oral preparations of release morphine ready (every 4 hours).

Then switch to oral controlled-release preparations (every 12 hours).

Extra doses of immediate-release access to pain is not controlled.

STANDARD DOSE NOT EXIST. Typically less than 100 mg every 4 hours

In case of problems for oral administration (intestinal obstruction, malabsorption, persistent vomiting) the subcutaneous infusion is preferred; better to avoid intramuscular and intravenous

The epidural infusion can be made for administering the analgesic into the epidural space and periradicular.
This type of administration reduces the side effects due to systemic distribution of the drug


SIDE EFFECTS
• Sedation (reduce dose, make use of psychostimulants)
• Nausea and vomiting (antiemetics or resort to using oxycodone than morphine, oxycodone usually has less tendency to cause vomiting)
• Constipation (laxatives or oral naloxone)
• Liberation histamine (antihistamines)
• Respiratory depression (naloxone)
• If you try another opioid tolerance (cross-tolerance is not always complete)

OTHER SELLING OPIOIDS
• Oxycodone (less nausea)
• Hydromorphone (more powerful, and lower volumes for infusion)
• Levorphanol (long half-life)
• Methadone (best oral absorption)
• Fentanyl (suitable for transdermal preparations to be used for chronic pain, not acute)
• Meperidine (not suitable for chronic treatments)


CO-ANALGESICS

Local anesthetics for regional analgesia
Local anesthetics have drawbacks related to
• rhythms of injection,
• CNS effects and
• cardiovascular effects


Nerve block
May be used
• local anesthetics (limited effects over time),
• surgical approaches or
• neurolytic agents such as alcohol or phenol.

The use of nerve block is of interest in patients who do not respond to analgesics and limited life expectancy.
Neurogenic pain usually does not respond.


Analgesics inhalers
Subanesthetic doses of nitrous oxide and oxygen cause analgesia without loss of consciousness
May be useful in case of:
• post-operative pain,
• pain of childbirth,
• removing patches,
• various emergencies


Rubefacient
Rubefacient containing capsaicin may act either for cutaneous stimulation, both for depletion of substance P.

Clonidine
May increase the analgesic effect of opioid compounds.


DRUGS ADJUVANTS
Analgesics are not in the strict sense.

Tricyclic antidepressants
Doses lower than those antidepressant are useful for the neurogenic pain
• Amitriptyline is the most widely used drug, even
• the mianserin may be useful
The mechanism of action is uncertain.

Antiepileptic
Carbamazepine can be useful in neurogenic pain (trigeminal neuralgia).
Although gabapentin is useful in the treatment of neuropathic pain.

Antiarrhythmics
Flecainide and mexiletine are useful for neurogenic pain.
Caution in patients with heart problems.

Corticosteroids
Dexamethasone, methylprednisolone, and others are used in neurogenic pain.
It is thought to act by reducing edema, inflammation and compression of the nerve tissue.

Ketamine
Ketamine has some efficacy in the treatment of neuropathic pain (BMJ)

Phenothiazines
The methotrimeprazine) for EPR is useful in the treatment of neurogenic pain, antidepressants and carbamazepine.

Hydroxyzine
This has antihistamine and anti-emetic action synergize with opioids for pain relief

Muscle relaxants
Benzodiazepines, baclofen and dantrolene are useful for muscle spasms from cancer.
Spasmolytic antimuscarinic for visceral pain

Bisphosphonates and calcitonin
May be useful in pain from bone metastases. Their effect, however, and istaura after long latency.

Radiotherapy or treatment with Strontium-89
Palliative radiation therapy may be done in the case of
bone metastases with severe pain in the bones

Antiemetics
Dopamine antagonists, 5-HT3 antagonists, NK-1 antagonists.

Laxatives
Lactulose, Senna, Naloxone oral

Psychostimulants
Methylphenidate and dextroamphetamine can synergize with opioids for analgesic effect
They are used in patients with life expectancy does not long for serious forms of depression (in patients with severe pain from cancer).

In patients with longer life expectancies, start simultaneously with SSRIs, and gradually reduce the dose of psychostimulant
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