Opioid analgesics fentanyl, meperidine

Opioids Heroin Fentanyl, meperidine Strong agonist opioid analgesics... 

Acute pain is managed with either nonopioids such as acetaminophen, NSAIDs, or, when severe, opioids such as meperidine, morphine, methadone, hydromor-phone, fentanyl, or sufentanil (Golianu et ah, 2000). The latter are generally used parenterally, and when the patient is converted to oral analgesics, agents such as codeine, oxycodone, and hydrocodone are often used. 

Opioid analgesics (see Chapter 14) are the primary medications used during PCA.9 Opioids such as morphine, meperidine, tramadol, fentanyl, and fentanyl... 

Prescription regulations for most CNS drugs are based on their abuse liability. The potent opioid analgesics (e.g., morphine, methadone, meperidine, fentanyl) are judged to have the highest potential for abuse, along with CNS stimulants (e.g., amphetamine, cocaine) and short-acting barbiturate (e g., secobarbital). No refills or telephone prescriptions are permissible. 

It has been possible to produce a balanced type of anesthesia wherein low-potency N20 is combined with an opioid analgesic, usually the meperidine analog fentanyl (Fig. 5-10), or the more recent analogs sufentanil and alfentanil. When a butyrophenone-type neuroleptic (see later), particularly droperidol, is added, a state of neuroleptoanesthesia is produced where, without loss of consciousness, analgesia sufficient for surgery is achieved during which the patient still responds to commands.6... 

Opioid drugs and peptides that bind to the opioid receptors produce the primary general and specific clinical effects summarized in Table 8.1. The opioids relevant to this review are those that are used in medicine today meaiung, therefore, the frequently administered analgesics, particularly morphine, codeine, and synthetic analogs such as fentanyl, meperidine, and methadone. 

Fig. 8.1 Comparison of the structures of morphine and some important synthetic opioid analgesics. While clear similarities in stmctnre are not always obvious, both morphine and meperidine have a phenylpipeiidine structure and a phenylpropylamine grouping, highlighted here as a sequence of three carbons hiiked to the aromatic ring via the central C13 carbon in morphine and C4 in meperidine and terminating in an Ai-methyl gronp. Fentanyl, alfentaml, remi-fentanil, and sufentanil contain a 4-anihdophenylpiperidine and a 4-anihdophenylpropylamine (highlighted) structure.

Fentanyl is a synthetic opioid analgesic, introduced in the 1950s, that has enhanced analgesic activity and potency and fewer adverse effects compared with morphine or meperidine. Structurally related to meperidine, fentanyl gained wide popularity as an intra-operative anesthetic adjunct as well as an effective analgesic for the management of acute and chronic pain. 

Severe pain should be treated with an opioid such as morphine, hydromorphone, methadone, or fentanyl. Moderate pain can be treated effectively in most cases with a weak opioid such as codeine or hydrocodone, usually in combination with acetaminophen. Meperidine should be avoided owing to its relatively short analgesic effect and its toxic metabolite, normeperidine. Normeperidine may accumulate with repeated dosing and can lead to central nervous system side effects including seizures. 

Semi-synthetic and synthetic opioids (meperidine, hydrocodone, fentanyl, etc.) are the result of many attempts to produce effective yet safer analgesics. The fact that both morphine and codeine are still widely used indicates that the newer opioids have been only moderately successful. However, current knowledge of the opioid system makes the goal of producing the perfect... 

Fentanyl (Sublimaze), sufentanil (Sufenta), alfentanil (Alfenta), remifentanil (Ultiva), meperidine (Demerol), and morphine are the major parenteral opioids used in the perioperative period. The primary analgesic activity of each of these drugs is produced by agonist activity at p-opioid receptors. Their order of potency (relative to morphine) is sufentanil (lOOOx) > remifentanil (300x) > fentanyl (lOOx) > alfentanil (15x) > morphine (lx) > meperidine (O.lx). 

The term opioids refers to these and other derivatives of naturally occurring opium (eg, morphine, heroin, codeine, and hydrocodone) as well as new, totally synthetic opiate anaiogs (eg, fentanyl, butorphanol, meperidine, and methadone Table 11-43). A wide variety of prescription medications contain opioids, often in combination with aspirin or acetaminophen. Dextromethorphan (see p 183) is an opioid derivative with potent antitussive but no analgesic or addictive properties. Tramadol (Ultram )... 

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