Inhaled fentanyl

Higgins et aL [2] assessed the effects of three concentrations of inhaled nebulized fentanyl citrate solution given for post operative pain relief. Among the 30 studied patients, the patients inhaling a more concentrated solution of fentanyl citrate over 9 minutes showed a moderate analgesic response within 5 min of inhalation. In this study inhaled fentanyl did not prove more effective than the other parenteral formulations. Inhalation of 300 pg of fentanyl from the nebuhzer produced a peak concentration of 0.4 ng/mL at 2 min and a plateau concentration of 0.1 ng/mL at 15 min, while with inhalation of 100 pg, blood levels remained stable at 0.02 ng/mL. 

Another small study assessed the effectiveness of fentanyl delivered by aerosol for post-operative analgesia. The seven patients receiving 300 pg of inhaled fentanyl had a significant improvement versus patients receiving 100 pg. There were no adverse effects such as respiratory depression, bronchospasm, nausea or drowsiness reported in this study [3]. 

In Hungs prehminary study [5] comparing nebulizer and intravenous administration of fentanyl, delivery of 2000 pg of a nebulized mixture of free (50%) and liposomal-encapsulated (50%) fentanyl (FLEF) to volunteers resulted in a peak plasma concentration of 1.15 ng/mL at 22 min. One important feature of the FLEF was that the plasma concentration decreased slowly after the single 2000 pg dose. At 8 and 24 h after inhalation, fentanyl concentration values were 0.25 0.14 ng/mL and 0.12 0.16 ng/mL, respectively (Figure 111.2). 

Two inhaled fentanyl preparations are currently under investigation. AeroLEF is mixture of free and Uposome-encapsulated fentanyl delivered through breath-actuated nebulizers. It is designed to rapidly achieve therapeutic concentrations through absorption of the free component, followed by release of fentanyl from liposomes and continued pulmonary absorption to extend the duration of action. Inhalation of small doses of free fentanyl in AeroLEF ... 

In addition, the problems inherent in delivering analgesia to a patient with difficult intravenous access, to a patient who would not need an intravenous line except to receive pain medication, or in the out-of-hospital setting make the idea of having an effective inhaled analgesic very attractive. Inhaled fentanyl may also be able to be given more quickly than intravenous analgesia and the equipment costs of nebulizers compare favorably with the cost of the supplies needed for intravenous administration. Inhaled fentanyl also proved to be beneficial in the pediatric population, where it is easy to administer and does not cause additional pain or distress to the child. 

Worsley MH, MacLeod AD, Brodie MJ, Ashury AJ, Clark C. Inhaled fentanyl as a method of analgesia. Anaesthesia 1990 45(6) 449-451. 

The interior volume of the theater, estimated from illustrations, was probably less than three hundred thousand cubic feet, i.e., about 10,000 cubic meters. Based on doses used for anesthesia, a concentration of as little as 2-3 mg per cubic meter of a super-potent Fentanyl derivative might be sufficient for a building that size, if instantaneous incapacitation is not required. This assumes continuous inhalation for about 30 minutes. Thus, if evenly distributed, the total amount of drug required might be in the range of a few dozen grams - almost certainly less than a pound. If the Russian authority pumped in 5x the effective dose (as it claimed), its uneven distribution in the air would likely have caused many deaths. But only one in six died. 

Opioids play an important role in anesthetic practice. Opioid analgesics potentiate the efficacy of anesthetics. They can be given as part of the premedication as well as during the operation. Examples of short acting agents with high potency are fentanyl, sufentanyl, alfentanil and remifentanil. Because of their hemodynamic stability these agents can be used for patients with compromised myocardial function. Respiration must be maintained artificially and may be depressed into the postoperative period. They are usually supplemented with inhalation anesthetic, benzodiazepines or propofol. 

Recovery is sufficiently rapid with most intravenous drugs to permit their use for short ambulatory (outpatient) surgical procedures. In the case of propofol, recovery times are similar to those seen with sevoflurane and desflurane. Although most intravenous anesthetics lack antinociceptive (analgesic) properties, their potency is adequate for short superficial surgical procedures when combined with nitrous oxide or local anesthetics, or both. Adjunctive use of potent opioids (eg, fentanyl, sufentanil or remifentanil see Chapter 31) contributes to improved cardiovascular stability, enhanced sedation, and perioperative analgesia. However, opioid compounds also enhance the ventilatory depressant effects of the intravenous agents and increase postoperative emesis. Benzodiazepines (eg, midazolam, diazepam) have a slower onset and slower recovery than the barbiturates or propofol and are rarely used for induction of anesthesia. However, preanesthetic administration of benzodiazepines (eg, midazolam) can be used to provide anxiolysis, sedation, and amnesia when used as part of an inhalational, intravenous, or balanced anesthetic technique. 

Adam see Ecstasy Adderall see Amphetamines Adipex-P see Diet pills Aerosol propellants see Inhalants African black see Marijuana African salad see Catha etlulis African tea see Catha etlulis Afterburner bromo see 2C-B Ah-pen-yen see Opium Air blast see Inhalants Alfenta see Fentanyl Allium sativum see Herbal drugs Alprazolam see Benzodiazepine Alurate see Barbiturates Amber see Herbal drugs Ambien see Tranquilizers American ephedra see Ephedra Amiloride see Diuretics Amitriptyline see Antidepressants Amobarbital see Barbiturates Amoeba see PCP (phencyclidine) Amoxapine see Antidepressants AMT see Dimethyltryptamine (DMT) Amy see Amyl nitrite Amyl nitrate see Amyl nitrite... 

Animal tranquilizer see PCP (phencyclidine) Antipsychotics see Tranquilizers Anxiolytics see Tranquilizers Apache see Fentanyl Aprobarbital see Barbiturates Aquachloral Supprettes see Tranquilizers Arabian tea see Catha etlulis Aroma of men see Inhalants Asendin see Antidepressants Ativan see Benzodiazepine A2 see Benzylpiperazine/Trifluoromethylphenyl-piperazine... 

Furthermore, high intravenous doses of opioids can cause chest wall rigidity, thereby acutely impairing ventilation, as well as postoperative respiratory depression requiring prolonged assisted ventilation and the administration of opioid antagonists (eg, naloxone). Low doses of fentanyl have been used as premedication and as an adjunct to both intravenous and inhaled anesthetics. 

Fentanyl Care should be taken to avoid skin contact and inhalation of fentanyl citrate to prevent adverse effects. Incompatibility has been reported with other drugs such as thiopentone sodium, methohexitone sodium, and fluorouracil.54 This drug should not be administered along with alkaline drugs. 

Caution. Avoid contact with skin and the inhalation of particles of fentanyl citrate. 

Inhalant abuse is also termed volatile solvent abuse. It should be noted that many drugs besides those classified as inhalants can be administered by inhalation, including marijuana, cocaine, heroin, methamphetamine, fentanyl patches, and nicotine. These drugs are not volatile solvents and have different physical and chemical properties therefore, they are not classified as inhalants. Inhalants are chemicals that are volatile, meaning they can readily vaporize from... 

Fentanyl (0.001 mg/kg i.v.) can be used with xylazine (0.44 mg/kg i.v.) for anesthetic premedication. Fentanyl is sometimes used as an anesthetic adjunct during inhalation anesthesia to improve analgesia. The pharmacokinetics of fentanyl make it ideal for administration by constant rate infusion and it can be administered intra-operatively at a rate of 0.001-0.004 mg/kg/h after a 0.001 mg/kg loading dose. To prevent excitement or locomotory stimulation in recovery, the infusion should be discontinued 30 min prior to recovery or the horse should be sedated with xylazine (0.1 mg/kg i.v.) prior to recovery. 

The inhalational anaesthetics increase the effects of the neuromuscular blockers to differing extents, but nitrous oxide appears not to interact significantly. Ketamine has been reported to potentiate the effects of atracurium. Propofol does not appear to interact with mivacurium or vecuronium. Xenon is reported not to interact with mivacurium or rocuronium, and has less effect than sevoflurane on vecuronium neuromuscular blockade. Bradycardia has been seen in patients given vecuronium with eto-midate or thiopental. Propofol can cause serious bradycardia if it is given with suxamethonium (succinylcholine) without adequate antimuscarinic premedication, and asystole has been seen when fentanyl, propofol and suxamethonium were given sequentially. 

In a subsequent study by the same author, five doses of 4000 pg FLEF were administered at 12-h intervals. The time to reach the peak concentration after each administration ranged from 12.5 to 19.2 min and the fentanyl concentration was maintained within the analgesic therapeutic concentration (0.6-3 ng/mL). The bioavailability of inhaled FLEF is 12-20%, which is consistent with the bioavailability of most drugs administered via the pulmonary system (10-20%). 

Following the initiation of AeroLEF inhalation, plasma concentrations of fentanyl rapidly entered the therapeutic range within minutes, with the majority of subjects attaining maximum plasma concentrations in <10 minutes. 

Figure 11U. Rate of absorption of fentanyl after inhalation of the mixture of free and liposome-encapsulated fentanyl. (With permission from Hung OR, Whynot SC, Varvel JR, Shafer SI, Mezei M. Anesthesiology. 83(2)r277-284, August 1995.) [5]...

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