Fentanyl physiological

Despite the limitations imposed by the physiology of the skin, several marketed controUed release transdermal dmg dehvery systems are available in the United States for example, scopolamine [51-34-3] for the treatment of motion sickness, nitroglycerin [55-63-0] for angina, estradiol [50-28-2] for the rehef of postmenopausal symptoms and osteoporosis, clonidine [4205-90-7] for the treatment of hypertension, fentanyl [437-38-7] as an analgesic, and nicotine [54-11-5] as an aid to smoking cessation. These systems are designed to dehver dmg for periods of one to seven days. 

Certain forms of conduction anesthesia, such as spinal anesthesia and some peridural anesthetics, can alter respiration by blocking intercostal nerves. Through other mechanisms, fentanyl injection can also alter respiration. Therefore, when fentanyl injection is used to supplement these forms of anesthesia, the anesthetist needs to be aware of the physiological alterations involved and manage them... 

The major physiological effects of fentanyl are euphoria, drowsiness, respiratory depression, decreased gastrointestinal mobility, nausea, and muscular rigidity. People build up a tolerance to fentanyl the more they use it, causing them to need more to obtain the same effects they once received from a smaller dose. The high of fentanyl can last 10-72 hours, depending on the ingestion method, the fentanyl derivative used, and the amount taken. 

Immunoassay detection of drugs in horses. I. Particle concentration fluoroimmunoassay detection of fentanyl and its congeners. Research Communications in Chemical Pathology and Pharmacology 57 389-407 MacDonald E, Scheinin M 1995 Distribution and pharmacology of a2-adrenoceptors in the central nervous system. Journal of Physiology and Pharmacology 46 241-258... 

S. Bjorkman, D. R. Wada, D. R. Stanski, and W. F. Ebling, Comparative physiological pharmacokinetics of fentanyl and alfentanil in rats and humans based on parametric single-tissue modeh. J Pharmacokinet Biopharm 22 381 10 (1994). 

Substitution of tetrazol-5-one for the thiophene ring in sufentanil results in a decrease in potency ( 25 times that of morphine) and a decrease in the pKa of the resultant compound, alfentanil (Table 24.4). The lower pKa of alfentanil results in a lower percentage of the drug existing in the ionized form at physiological pH. Being more un-ionized, alfentanil penetrates the blood-brain barrier faster than other fentanyl derivatives and has a faster onset and shorter duration of action. Alfentanil is 99% metabolized in the liver and has a half-life of only 1.3 hours. Alfentanil is available as an intravenous dosage form for use in ultrashort anesthetic procedures. 

Alfentanil is a tertiary amine with an ionization constant of 6.5 resulting in approximately 10% ionization at physiologic pH. When compared with fentanyl (II), I has. .. a much greater unionized fraction at physiologic pH."... 

Albrecht M, Henke J, Tacke S, Marker M, Guth B (2014) Effects of isoflurane, ketamine-xylazine and a combination of medetomidine, midazolam and fentanyl on physiological variables continuously measured by telemetry in Wistar rats. BMC Vet Res 10 198... 

Fentanyl, a synthetic chemical compound, was discovered to be about 100 times as potent as morphine or heroin. Its chemical structure shown in Fig. 17.11 indicates that it can also be classified as an alkaloid. This compound has been widely used as an anesthetic in surgical procedures, as the physiological effects are much shorter-acting than morphine. And it gives a high like heroin, though short-lived. 

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