Meperidine effects

Administration of atropine with meperidine (Demerol), flurazepam (Dalmane), diphenhydramine (Benadryl), phenothiazines, and the tricyclic antidepressants may increase the effects of atropine. There is a decreased effectiveness of haloperidol when administered with the anticholinergic dragp. 

Phenytoin interacts widi many different drugp. For example isoniazid, chloramphenicol, sulfonamides, benzodiazepines, succinimides, and cimetidine all increase phenytoin blood levels. The barbiturates, rifampin, theophylline, and warfarin decrease phenytoin blood levels. When administering the hydantoins with meperidine, die analgesic effect of meperidine is decreased. 

There is a decreased effectiveness of ritodrine when the drug is administered with a -adrenergic blocking agent such as propranolol and an increased risk of pulmonary edema when administered with the corticosteroids. Co-administration of ritodrine with the sym-pathomimetics potentiates the effect of ritodrine. Cardiovascular effects (eg, arrhythmias or hypotension) of ritodrine may increase when the drug is administered with diazoxide, general anesthetics, magnesium sulfate, or meperidine... 

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. 

Amphotericin B is the mainstay of treatment of patients with severe endemic fungal infections. The conventional deoxycholate formulation of the drug can be associated with substantial infusion-related adverse effects (e.g., chills, fever, nausea, rigors, and in rare cases hypotension, flushing, respiratory difficulty, and arrhythmias). Pre-medication with low doses of hydrocortisone, acetaminophen, nonsteroidal anti-inflammatory agents, and meperidine is common to reduce acute infusion-related reactions. Venous irritation associated with the drug can also lead to thrombophlebitis, hence central venous catheters are the preferred route of administration in patients receiving more than a week of therapy. 

Fever, rigors, chills, malaise headaches, myalgia Nausea, emesis Neutropenia Hepatic enzyme elevation Cutaneous—alopecia, transient, mild rashlike reaction Acetaminophen (APAP). NSAID if APAP is not effective. Meperidine for severe chills and rigors. Bedtime administration. 5-HT3 antagonist, prochlorperazine, metoclopramide, fluids Weekly complete blood count reduce dose by 30-50% Liver function tests (LFTs) weekly withhold treatment until LFTs normalize restart at 30-50% dose reduction reversible on dose reduction or cessation. Interferon is contraindicated in patients with psoriasis because exacerbation of psoriasis has been noted during IFN therapy. 

Extensive molecular dissection of the morphine molecule over the past several decades led to a host of molecules which showed narcotic analgesic activity even though they possessed but faint suggestion of the structural features present in morphine itself. Thus, both cyclic molecules such as meperidine (70) and alphaprodine (71), and acyclic Compounds such as methadone (72) were found to be effective analgesics. Common features of these compounds were formalized by the Beckett-Casy rule, which states as minimal required structural features (a) an aromatic ring attached to... 

Meperidine, an atypical opiate receptor agonist with cocaine-like effects, has been shown to act at the DAT.105 Meperidine inhibited [3H]DA uptake in rat caudate putamen with a maximal... 

The answer is e. (Hardmanr p 926.) Diphenoxylate is a piperidine opioid that is related to meperidine, it inhibits peristalsis and, hence, increases the passage time of the intestinal bolus. Lt is combined with atropine to discourage use as a street drug. Atropine has little effect on peristalsis. Clonidine, bismuth subsalicylate, and re hydration therapy are all useful in some types of diarrhea, but none of them inhibit peristalsis. 

Analgesics are given to reduce abdominal pain. In the past, parenteral meperidine (50 to 100 mg) every 3 to 4 hours was usually used because it causes less spasm of the sphincter of Oddi than other opioids. Meperidine is used less frequently today because it is not as effective as other opioids and is contraindicated in renal failure. Parenteral morphine is sometimes used, but it is thought to cause spasm of the sphincter of Oddi, increases in serum amylase and, rarely, pancreatitis. Hydromorphone may also be... 

Opioids and derivatives (e.g., meperidine, butorphanol, oxycodone, hydromorphone) provide effective relief of intractable migraine but should be reserved for patients with moderate to severe infrequent headaches in whom conventional therapies are contraindicated or as rescue medication after failure to respond to conventional therapies. Opioid therapy should be closely supervised. 

Meperidine (Figure 7.4) was introduced in the 1930s as an alternative to morphine for relieving pain. Its advantage over morphine was that its duration of action was shorter and it had fewer unwanted side effects such as sedation and constipation. 

Figure 7.4 The chemical structure of meperidine, its analogue MPPP, and the closely related neurotoxin MPTP, are all shown here. Meperidine, an anesthetic, was also used as an alternative to morphine. It proved advantageous because it has a shorter length of duration and fewer side effects than morphine.

The two most common analogs of meperidine used as recreational drugs are l-methyl-4-phenyl-4-propionoxypiperidine (MPPP) and l-[2-phenylethyl]-4-acetyloxypiperdine (PEPAP). These compounds have a number of street names, including new heroin, synthetic heroin, synthetic Demerol, and China White. MPPP and PEPAP have pharmacological effects similar to those of heroin, hut more pronounced, producing a sense of euphoria and release from the real world. MPPP, for example, is three times as potent has heroin. 

Spasmolytics. N-Butylscopolamine (p. 104) is used for the relief of painful spasms of the biliary or ureteral ducts. Its poor absorption (N.B. quaternary N absorption rate <10%) necessitates parenteral administration. Because the therapeutic effect is usually weak, a potent analgesic is given concurrently, e.g., the opioid meperidine. Note that some spasms of intestinal musculature can be effectively relieved by organic nitrates (in biliary colic) or by nifedipine (esophageal hypertension and achalasia). 

Both are classified as low-ceiling opioids (B), because neither is capable of eliciting the maximal analgesic effect obtained with morphine or meperidine. 

One of the early syntheses of meperidine (75) starts with the double alkylation of phenylacetonitrile with the bischloro-ethyl amine, 72. The highly lachrimatory nature of this material led to the development of an alternate synthesis for the intermediate piperidine (73). Alkylation of phenylacetonitrile with two moles of 2-chloroethylvinyl ether leads to the intermediate (69). This is then hydrolyzed without prior isolation to the diol, 70. Treatment with thionyl chloride affords the corresponding dichloro compound (71). This last is then used to effect a bis alkylation on methylamine, in effect forming the piperidine (73) by cyclization at the opposite end from the original scheme. Saponification to the acid (74) followed by esterification with ethanol affords the widely used analgesic meperidine (75) substitution of isopropanol for ethanol in the esterification affords properidine (76). ... 

Relief of pain - While subcutaneous administration is suitable for occasional use, IM administration is preferred for repeated doses. If IV administration is required, decrease dosage and inject very slowly, preferably using a diluted solution. Meperidine is less effective when administered orally than when given parenterally. Reduce proportionately (usually by 25% to 50%) when administering concomitantly with phenothiazines and other tranquilizers. 

Renal/Hepatic function impairment Renal and hepatic dysfunction may cause a prolonged duration and cumulative effect smaller doses may be necessary. Meperidine In patients with renal dysfunction, normeperidine (an active metabolite of meperidine) may accumulate, resulting in increased CNS adverse reactions. Pregnancy Category C, Category B, (oxycodone). 

Pharmacology Pentazocine, a potent analgesic, weakly antagonizes the effects of morphine, meperidine, and other opiates at the p-opioid receptor. 

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