Absorption hydromorphone

Opioids maybe administered in a variety of routes including oral (tablet and liquid), sublingual, rectal, transdermal, transmucosal, intravenous, subcutaneous, and intraspinal. While the oral and transdermal routes are most common, the method of administration is based on patient needs (severity of pain) and characteristics (swallowing difficulty and preference). Oral opioids have an onset of effect of 45 minutes, so intravenous or subcutaneous administration maybe preferred if more rapid relief is desired. Intramuscular injections are not recommended because of pain at the injection site and wide fluctuations in drug absorption and peak plasma concentrations achieved. More invasive routes of administration such as PCA and intraspinal (epidural and intrathecal) are primarily used postoperatively, but may also be used in refractory chronic pain situations. PCA delivers a self-administered dose via an infusion pump with a preprogrammed dose, minimum dosing interval, and maximum hourly dose. Morphine, fentanyl, and hydromorphone are commonly administered via PCA pumps by the intravenous route, but less frequently by the subcutaneous or epidural route. 

Oxycodone is nearly 10 times as strong as codeine, with absorption equal to that of orally administered morphine. Neither hydromorphone nor oxycodone is approved for use in children, and hydromorphone is contraindicated in obstetrical analgesia and in asthmatics. 

The PassPort system from Altea Therapeutics uses a thermal process to create an array of macropores across the stratum corneum. The device consists of a planar array system of small metallic filaments that rapidly converts electrical energy to thermal energy. The heat ablates the stratum corneum for a few milliseconds at a time and porates only the stratum corneum. After skin poration with this process, drug absorption occurs from a drug reservoir on the porated site. Hydromorphone and insulin delivery with this method is currently under human clinical testing. 

Hydromorphone is more potent, has better oral absorption characteristics, and is more soluble than morphine, but its overall pharmacologic profile parallels that of morphine. A sustained-release hydromorphone product has recently become available. Oxymorphone can be administered rectally and by injection. Although it is more potent than morphine, it offers no real pharmacologic advantages. Levor-phanol has an extended half-life, bnt its overall therapeutic effects are similar to those of morphine. 

Absorption In general, the opioids are absorbed readily from the GI tract absorption through the rectal mucosa is adequate, and a few agents e.g., morphine, hydromorphone) are available in suppositories. The more lipophilic opioids also are absorbed readily through the nasal or buccal... 

Pharmacokinetic data in healthy subjects has shown that consuming alcohol with a particular 24-hour extended-release formulation of hydromorphone (Palladone XL Capsules Purdue Pharma, USA) could lead to rapid release (dose dumping) and absorption of a potentially fatal dose of hydromorphone. Although no reports of serious problems had been re-... 

Food can delay the absorption of dextropropoxyphene (propoxyphene), but the total amount absorbed may be slightly increased. Food increases the bioavailability of oral morphine solution and produces a sustained serum level, however, the absorption of some controlled-release preparations of morphine may be delayed by food. Food may also increase the bioavailability of oxycodone solution, but sustained-release preparations of oxycodone and tramadol and immediate-release hydromorphone appear not to be affected by food. 

Epidural hydromorphone s primary site of action is at endogenous opioid receptors located on neurons in lamina 1-11 (substantia gelatinosa) and lamina V of the spinal dorsal horn. Following epidural administration, hydromorphone enters the spinal cord and activates pre- and postsynaptic mu receptors and suppresses pain transmission. Systemic absorption and activation of central opioid receptors may provide additional analgesia. Hydromorphone is not particularly hydrophilic, and rostral migration in CSF is of lower magnitude than that observed with morphine. Rostral spread of hydromorphone may result in undesirable side effects such as pruritus, nausea and vomiting, and sedation. Epidural hydromorphone is associated with dose-dependent reductions in respiratory rate and minute ventilation however, unlike morphine, delayed-onset respiratory depression is less likely to occur [3,4]. 

Drug interactions same as hydromorphone. Decreased plasma concentrations may result from gastrointestinal hyper-motility syndromes due to excretion before absorption. 

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