Pharmacology Chapter 28

Analgesics are drugs that relieve pain without causing loss of consciousness.

A general term defined as any drug, natural or synthetic, that has actions similar to those of morphine. Opioids are narcotics, but opioid is preferable terminology to narcotic.

A more specific term and applies only to compounds present in opium (eg. morphine, codeine).

1. Narcotic (Addictive)
2. Non-narcotic (not addictive)

Narcotics are addicitve, narcotics are stronger and more likely to be abused. Examples of narcotics are morphine, hydrocodone and examples of non-narcotics are tylenol and ibuprofen.

1. Narcotics act on the CNS - they are lipid soluble which is why they have a stronger impact than non-narcotics. Pain impulses are NOT transmitted to the brain and respiratory and cough centers are suppressed.
2. Non narcotics act on peripheral nervous system (autonomic and voluntary).

How many receptors are affected.

mu, kappa and delta.

Mu receptors because opioid analgesics act primarily on mu receptors, although they also produce weak activation on kappa receptors.

Analgesia, respiratory depression, euphoria, and sedation. Mu activation is also related to physical dependence.

Drug that produces a response. Drug binds with a receptor.

Drug that produces a partial response.

Drug that produces a mixed response.

antitussive

Respiratory depression. Cellular changes occur - CO2 levels can rise before you actually have respiratory suppression

When using IV, within minutes and can last for 4-5 hours. If med given spinally can last even longer. Be prepared with BVM, O2, reversal drugs, and protect airway (position & suctioning).

Pinpoint pupilsb (miosis), bradypnea <8 down to respiratory arrest.

Alcohol, sedatives, hypnotics, antipsychotics, and muscle relaxants.

Antidote = narcotic antagonist. An antagonist has a higher affinity for the receptor than the agonist (narcotic). It bumps the narcotic off the receptor.

Naloxone is an antagonist - brand name is Narcan. Drug of choice for treating pure opiod overdose. Half life is much shorter than that of narcotic so small doses must be given frequently until effects of narctotics are gone.

Morphine for relief of moderate to severe pain. More effective against constant, dull pain than against sharp, intermittent pain. Drug of choice for Myocardial Infarction.

IV- 1-10 mg per dose (PCA), IM-5-20 mg. per dose, PO 10-30 mg., SQ-same as IM. Intrathecal and Spinal must be preservative free, and rectally.

CNS: drowsiness, lethartgy, Resp: depression, GI: stimulates vomiting, decreases peristalsis, eyes: miosis, GU: diminished need to void, CV: hypotension, upper body flushing.

Nausea (in ambulatory patients), constipation, sedation, orthostatic hypotension, urinary retention.

Patient Controlled Analgesia pump, used to deliver analgesia when patient presses button. Intervals and amounts are precalculated.

Peope who do not normally take narcotics - it would knock them out.

PCA uses about 1/10th of the narcotic the RN would have given.

When you need more of the drug to produce desired results. For example, euphoria, sedation, analgesic and respiratory depression.

Physical dependence is not tolerance. It is the body's reaction to being without the drug. Reactions can include shivering, body aches, cramps, runny nose.

Merepidine (Demerol) - similar effects to those of morphine, but with shorter half life, very effective orally, no miosis. Demerol is effective for patients who are allergic to morphine and seems to stop the shivers after surgery.

Fentanyl (Subliaze, Innovar, Duragesic)

100x stronger than morphine! Given as an adjunct to morphine or anesthesia, can be used PCA or in a patch form. Actiq is a lollipop form which can be used for breakthrough pain.

Codeine. Some people have genetic block for this process and codeine is ineffective for them. Used for mild to mederate pain.

Codeine is 1/10th the strength of MS, but 5x as strong as ASA or acetaminophen, does not produce as much ICP and is a good choice for neuro patients because it is not as sedating as MS. Common to mix with ASA or acetaminophen.

Diacetyl morphine. Lipid soluble, enters brain fastter than MS but not as potent an analgesia as MS. Converted to MS in the body and is frequently "cut" with other substances. Schedule I drug.

Methadone. Analgesia = Morphine. Longer 1/2 life. Longest duration of action of any narcotic. Used for detox, maintenace - withdrawal is much milder than that of MS.

Hydrocodone. Used as an analgesic and an antitussive. Common Rx for patients.

Percodan is Oxycodone mixed with aspirin. Percocet is Oxycodone + acetaminophen. 10x stronger than codeine. Oxycontin is extended release form. Common Rx for patients.

Diarrhea

Dextromethorphan. Chemically related to opiates, but strictly antitussive.