Meperidine oral administration

Anileridine, ethyl l-(4-amino phenethyl)-4 phenylisonipecotate is available in the form of its dihydrochloride for oral administration and as the phosphate for injection (Leritine ). Its analgesic potency is intermediate between that of meperidine and morphine. Similar to meperidine, it exerts mild antihistaminic and spasmolytic effects, but it is devoid of the constipating effect of opiates. Sedative and direct hypnotic effects are similar to those of meperidine but less than those of morphine. 

Meperidine is absorbed by all routes of administration, but the rate of absorption may be erratic after intramuscular injection. The peak plasma concentration usually occurs at about 45 minutes, but the range is wide. After oral administration, only about 50% of the drug escapes first-pass metabolism to enter the circulation, and peak concentrations in plasma usually are observed in 1 to 2 hours. 

After oral administration, the levels of normeperidine are increased compared to systemic administration. In hepatic disease, the reduced hepatic clearance of meperidine results in increased absorption necessitating a reduction in dose. Following intramuscular administration of meperidine, the elimination half-life (f P) is 3.6 hours (3.1-4.1 hours). Intramuscular absorption is highly variable with a two-fold variation in blood levels in the same patient and a wider five fold intra-patient variability. The l P is 111.4 hours in cirrhotic patients (range 8.3-18.7), but the levels of normeperidine are reduced. The elimination half-life of meperidine and normeperidine are prolonged in patients with renal failure. The l P elimination half-life of normeperidine is anywhere from 14-21 h to 24-48 h and as long as 34 h in renal failure [3]. 

Approximately 50% of oral meperidine is absorbed into the systemic circulation (range 41 to 61%). After oral administration the onset of analgesia is within 15 minutes and peak effects occur in 60-90 minutes [1,3]. In hepatic disease, with reduced hepatic clearance, the absorption of meperidine is increased from the gastrointestinal tract, necessitating a reduced dose. 

Unlike morphine and meperidine, methadone is well absorbed from the gastric mucosa, and has high oral bioavailability of around 75% (36-100%). It can be detected in blood 15-45 minutes after oral administration, and peak plasma concentration is achieved at 2.5-4 hours. Methadone is highly bound to plasma proteins, in particular to al-acid glycoprotein. 

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. 

Meperidine (Demerol) [C-ll] [Narcotic Analgesic] Uses Moderate/ severe pain Action Narcotic analgesic Dose Adults. 25-50 mg IV, 50-100 mg IM Peds. 1 mg/kg IV/IM (onset w/in 5 min IV and 10 min IM duration about 2 h) Caution [C, ] Contra Convulsive disorders and acute abdomen Disp Prefilled 1 mL syringes 25, 50, 75, 100 mg/mL various amps and vials oral syrup and tabs SE N/V (may be severe), dizziness, weakness, sedation, miosis, resp d ession, xerostomia (dry mouth) Interactions t CNS depression W/ opiates, sedatives/ hypnotics TCNS stimulation W/amphetamines t risk of tox W7 phenytoin EMS Pt should be receiving O2 prior to administration have resuscitation equipment and naloxone available naloxone can be used as an antidote to reverse resp depression aspirate prior to IM administration inadv tent IV admin of IM doses may cause tach and syncope mix w/ NS to make a 10 mg/mL soln and inj very slowly N/V may be sev e may premedicate w/ an antiemetic... 

Frequently, a preoperative sedative is given to a patient 1 to 2 hours before the administration of general anesthesia.2,36 Sedatives are usually administered orally or by intramuscular injection, and are given while the patient is still in his or her room. This approach serves to relax the patient and reduce anxiety when arriving at the operating room. Commonly used preoperative sedatives include barbiturates (secobarbital, pentobarbital), opioids (butorphanol, meperidine), and benzodiazepines (diazepam, lorazepam) (Table 11-2). Different sedatives are selected depending on the patient, the type of general anesthesia used, and the preference of the physician. 

Meperidine is available in the form of tablets (50 mg) for oral use or in solution (50 mg/ml) for intramuscular administration. It is administered in doses of 50 to 100 mg at 3- to 4-h intervals. Because of its antispasmodic effects, it is particularly useful in pain due to colic. It is also used prior to anesthesia, particularly cyclopropane. Meperidine is used in asthma, but its tendency to addiction limits its use in this condition to acute attacks. 

Injections of meperidine can be given intramuscularly (in the muscle), subcutaneously (under the skin), and intravenously (directly into the bloodstream). The body responds more readily to meperidine when it is injected, so dosages are usually about half that of the oral form, again every three to four hours. As with other opioids, intravenous administration of meperidine is often given at a low, continual dose. 

Actions Meperidine causes a depression of respiration similar to that of morphine, but there is no significant cardiovascular action when the drug is given orally. On intravenous (IV) administration, meperidine produces a decrease in peripheral resistance and an increase in peripheral blood flow, and may cause an increase in cardiac rate. As with morphine, meperidine dilates cerebral vessels, increases cerebrospinal fluid pressure, and contracts smooth muscle (the latter to a lesser extent than does morphine). In the gastrointestinal tract, meperidine impedes motility, and chronic use results in constipation. Meperidine does not cause pinpoint pupils, but rather causes the pupils to dilate because of an atropine-like activity. 

Meperidine is commercially available in parenteral solutions for intravenous and intramuscular administration and in oral tablets and solution. 

Chlorpromazine increases the respiratory-depressant effects of meperidine, as do tricyclic antidepressants this is not true of diazepam. Concurrent administration of drugs such as promethazine or chlorpromazine also may greatly enhance meperidine-induced sedation without slowing clearance of the drug. Treatment with phenobar-bital or phenytoin increases systemic clearance and decreases oral bioavailability of meperidine this is associated with an elevation of the concentration of normeperidine in plasma. As with morphine, concomitant administration of an amphetamine has been reported to enhance the analgesic effects of meperidine and its congeners while counteracting sedation. 

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