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Pain treatment in the ICU: intravenous, regional or both?

Adequate treatment of pain in ICU patients should be an integral part of ICU management, as inadequately treated pain leads to a series of complications that may counteract the success of ICU treatment. For continuous intravenous use we recommend sufentanil in a dose of 0.75-1.0 microgram kg-1 h-1 in mechanically ventilated patients and in a dose of 0.25-0.35 microgram kg-1 h-1 in intubated and spontaneously breathing patients. On-demand analgesia, administered via the intravenous or epidural route, may be an alternative to a relatively fixed continuous infusion of an analgesic drug, and in some ICU patients the transdermal use of opioids can be an alternative to continuous intravenous drug application or PCA. Increased sizes of the patch (25, 50, 75, 100 cm2) provide sustained transdermal rates of approximately 25, 50, 75 and 100 micrograms h-1 of fentanyl over a period up to about 72 hours. Patients with trauma to the thorax, pelvic fracture, or after major surgical interventions will be better managed by regional application of analgesic drugs alone or in combination with a systemic analgesic drug infusion. To achieve the best results it is necessary to be well informed and trained in the method, to know the advantages and disadvantages, the correct and modified dosages of the drugs used, and the indications and contraindications.

Administration, Cutaneous↗

The efficacy and fetal-maternal cardiovascular effects of transdermal glyceryl trinitrate in the prophylaxis of pre-eclampsia and its complications: a randomized double-blind placebo-controlled trial.

OBJECTIVES: Pre-eclampsia continues to be a major cause of maternal and perinatal mortality. A disorder of the nitric oxide system is implicated in the pathogenesis of this condition and preliminary studies have suggested a possible therapeutic role for nitric oxide donors in women with established pre-eclampsia. The aim of this study was to determine whether pre-eclampsia and its complications could be prevented by the long-term use of nitric oxide donors in a group of women identified to be at risk on the basis of abnormal uterine artery Doppler measurements. STUDY DESIGN: We enrolled 40 healthy normotensive women at high risk of pre-eclampsia selected on the basis of abnormal uterine artery Doppler waveforms at 24-26 weeks of gestation. Women were randomly allocated to receive transdermal glyceryl trinitrate 5 mg-patches or equivalent placebo patches in a double-blind randomized study. The primary outcome measures were pre-eclampsia, fetal growth restriction, preterm delivery or small for gestational age/fetal growth restriction rates. Patches were worn daily from recruitment for 10 weeks or until delivery. RESULTS: The primary outcomes were not significantly different in the placebo compared to the glyceryl trinitrate group. However, survival analysis of adverse events with gestation in both groups showed a significantly reduced risk of an adverse event in the glyceryl trinitrate group (p = 0.004), equating to a 73% reduction in hazard. There was no difference in maternal systolic and diastolic blood pressure, mean uterine artery resistance index and fetal umbilical and middle cerebral artery pulsatility indices between the groups. CONCLUSIONS: Low-dose prophylactic transdermal glyceryl trinitrate commenced late in the second trimester did not reduce the incidence of pre-eclampsia, preterm delivery or fetal growth restriction, but may increase the likelihood of a complication-free pregnancy. Transdermal glyceryl trinitrate (5 mg/day) did not affect maternal cardiovascular, uterine artery or fetal arterial Doppler parameters.

Administration, Cutaneous↗

Clonidine patch toxicity.

Five published case reports of clonidine patch toxicity in pediatric patients bring to light the importance of educating the public regarding appropriate use and disposal of transdermal drug-delivery systems. With the increasing use of clonidine transdermal delivery systems it is important that clonidine patch toxicity be considered in pediatric patients presenting with symptoms of depressed consciousness, miosis, hypoventilation, hypotension, bradycardia, hypothermia, cardiac dysrhythmias, hypotonia, or convulsions. Appropriate early supportive management is essential to avoid serious morbidity or mortality in the pediatric patient, and is reviewed herein.

Accident Prevention↗

[The bioavailability of transdermal therapeutic system of timolol].

A matrix-type transdermal therapeutic system of timolol (TTS-timolol) was well prepared. The patch consisted of backing membrane layer, timolol reservoir layer, pressure sensitive adhesive layer and protective layer. A sensitive and reliable HPLC-UV method for the determination of plasma level of timolol in healthy volunteers was developed. Effective therapeutic plasma level of timolol (4 ng/ml) was attained 4 h after application of the timolol patches and was maintained within 32 h while the patch was removed at 24 h. The pharmacokinetic behavior of this transdermal therapeutic system (TTS)-timolol in human showed zero order absorption and well fitted to a one compartment model. The pharmacokinetic parameters are: Tmax = 18.8 h; Cmax = 11.2 ng/ml; AUC = 265.7 ng/ml.h; Vss = 120.0 L; K = 0.084 h-1. In comparison with the results of oral administration of timolol tablets, TTS-timolol possesses some advantages: stable plasma level, long effective time and convenient administration.

Administration, Cutaneous↗

Effect of transdermal hormone replacement therapy on the monocyte chemoattractant protein-1 concentrations and other vascular inflammatory markers and on endothelial function in postmenopausal women.

Monocyte chemoattractant protein-1 (MCP-1) is related to the progression of atherosclerosis. However, little is known about the effects of transdermal hormone replacement therapy (HRT) on circulating MCP-1, vascular inflammatory marker concentrations, and endothelial function in postmenopausal women. The effects of transdermal HRT on circulating MCP-1, vascular inflammatory marker concentrations, and endothelium-dependent vasodilation were investigated in postmenopausal women. Thirty-three women received transdermal HRT (continuous 17-beta estradiol patch 36 microg/day plus cyclic oral medroxyprogesterone acetate 2.5 mg/day for 12 days/month) for 12 months, and 27 control patients did not. Brachial artery flow-mediated vasodilation (FMD), assessed by ultrasound, and circulating MCP-1 and vascular inflammatory marker (C-reactive protein, intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1], and E-selectin) concentrations were measured before and after 12 months of treatment. In the HRT group, MCP-1 concentrations decreased significantly (p <0.001), and ICAM-1, VCAM-1, and E-selectin concentrations decreased significantly (p <0.01 for all), but C-reactive protein concentrations did not change. MCP-1 and other marker concentrations did not change in the control group. FMD increased significantly in the HRT group (p <0.001) but did not change in the control group. Nitroglycerin-induced vasodilation did not change in either group. In conclusion, transdermal HRT decreased MCP-1 and cell adhesion molecule concentrations and improved endothelial function in postmenopausal women. Transdermal HRT may exert an antiatherosclerotic effect by improving MCP-1 and cell adhesion molecule expression and endothelial function.

Administration, Cutaneous↗

Emerging delivery systems for estrogen replacement: aspects of transdermal and oral delivery.

The ideal preparation for estrogen replacement therapy has been the object of intensive research for decades, and the search continues. More than 40 new products are in development in the United States, the United Kingdom, and Europe. Most are transdermal, which reflects the growing acceptance of patch technology at a time when the overwhelming majority of women who use estrogen replacement take oral formulations. Most of the new oral formulations are a combination of estrogen and progestin. Aspects of transdermal and oral estrogen are discussed, including the advantages and disadvantages for use in women with concomitant medical conditions.

Administration, Cutaneous↗

Effect of transdermal hormone replacement therapy on carotid artery wall thickness and levels of vascular inflammatory markers in postmenopausal women.

Carotid intima-media thickness (IMT) and vascular inflammatory markers have been shown to be involved in atherosclerosis. This study was designed to investigate the effect of transdermal hormone replacement therapy (HRT) on carotid IMT and vascular inflammatory markers in postmenopausal women and to explore the interrelationship between the change in carotid IMT and the changes in vascular inflammatory markers. Thirty-five postmenopausal women (mean age 57.0+/-7.7 years) received transdermal HRT (continuous 17beta-estradiol patch [36 microg/day] plus cyclic oral medroxyprogesterone acetate [2.5 mg/day, for 12 days/ month]) for 12 months, and 32 controls (mean age 58.0+/-7.5 years) did not. Carotid IMT, assessed by ultrasound, and circulating vascular inflammatory markers, i.e., C-reactive protein (CRP), intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, E-selectin, monocyte chemoattractant protein (MCP)-1, and matrix metalloproteinase (MMP)-9 were measured before and after 12 months of treatment. In the HRT group, carotid IMT decreased significantly (p<0.01), from 0.71+/-0.13 mm to 0.65+/-0.12 mm, and the ICAM-1, VCAM-1, E-selectin, and MCP-1 levels decreased significantly (p<0.01 for all), but the CRP and MMP-9 levels remained unchanged. Carotid IMT and vascular inflammatory markers were unchanged in the control group. In the HRT group, the change in carotid IMT was significantly correlated with the change in serum E-selectin (r=0.38, p<0.05), but not with the changes in other vascular inflammatory markers. These results suggest that transdermal HRT reduced carotid artery wall thickness, and that the reduction may have been induced by an antiatherosclerotic effect combined with the direct effect of estrogen and decreased levels of estrogen-induced E-selectin.

Administration, Cutaneous↗

Transdermal hormone replacement therapy in postmenopausal women with uterine leiomyomas.

OBJECTIVE: To evaluate the effects of transdermal hormone replacement therapy (HRT) on uterine and leiomyoma size and on uterine bleeding patterns in postmenopausal women with uterine leiomyomas. METHODS: The required sample size was calculated to be 30 subjects per group to detect an effect on the size of one standard deviation (SD) with an alpha value of 0.05 (two-sided) and a power 1 - delta = 0.8. At the end of the study, the power analysis showed a value of beta = 0.826. Seventy postmenopausal women with uterine leiomyomas were enrolled and treated for 12 cycles of 28 days each with transdermal 17 beta-estradiol (E(2)) patches plus oral medroxyprogesterone acetate continuously added (group A) or with calcium carbonate (group B). At entry and every three cycles, uterine and leiomyoma dimensions were measured by transvaginal ultrasonography. To evaluate the effect of transdermal HRT on the characteristics of uterine bleeding, 35 healthy postmenopausal women without uterine leiomyomas (group C) were enrolled and treated with the same regimen as group A. A daily diary was used to record the abnormal uterine bleeding episodes, and a rank scale was used to assess the severity of bleeding. RESULTS: There were no significant changes in mean uterine or leiomyoma size between groups A and B, or in each group compared with basal values. No significant difference was detected between groups A and C in uterine bleeding patterns. CONCLUSION: Transdermal HRT did not increase the size of uterine leiomyomas or affect uterine bleeding patterns in postmenopausal women.

Administration, Cutaneous↗

Contingent monetary reinforcement of smoking reductions, with and without transdermal nicotine, in outpatients with schizophrenia.

This study was conducted to examine the effects of contingent monetary reinforcement (CM) for smoking reduction, with and without transdermal nicotine, on cigarette smoking in individuals with schizophrenia. Fourteen outpatients participated in each of 3 conditions: (a) CM combined with 21 mg transdermal nicotine, (b) CM combined with placebo patch, and (c) noncontingent reinforcement combined with placebo patch. Each condition lasted 5 days. Carbon monoxide levels were measured 3 times daily, and nicotine withdrawal symptoms were measured once daily in each condition. Results indicated that CM reduced smoking but that 21 mg transdermal nicotine did not enhance that effect. These results offer further evidence supporting the efficacy of CM for reducing smoking among people with schizophrenia, but higher doses of nicotine replacement therapy, or another pharmacotherapy, may be needed to enhance that effect.

Administration, Cutaneous↗

Bioequivalence evaluation of the metabolites 1,2 and 1,3-glyceryl dinitrate of two different glyceryl trinitrate patches after 12-h usage in healthy volunteers.

In the course of this study both the bioavailability and main pharmacokinetic parameters of the glyceryl trinitrate (GTN, CAS 55-63-0) metabolites 1,2 and 1,3-glyceryl dinitrate (1,2-GDN and 1,3-GDN) were to be determined following transdermal application of a glyceryl trinitrate test patch (Deponit 5) and an already marketed reference patch. For this purpose, both patches were examined in healthy volunteers according to a randomized two-way cross-over design, blood samples were withdrawn up to 15 h after start of patch application and the plasma concentrations of both metabolites were quantified using a GC/MS method. The investigation showed the following results: Metabolite 1,2-glyceryl dinitrate: For the area under the curve from time 0 to the last quantifiable sample (AUC(0-Tlast) arithmetic mean values of 23.77 h.ng/ml (test patch) and 27.83 h.ng/ml (reference patch) were found. The corresponding peak plasma levels were 2.45 ng/ml and 2.93 ng/ml, respectively; they were reached after 6.4 h (test patch) and 8.31 h (reference patch). Metabolite 1,3-glyceryl dinitrate: The arithmetic mean values for AUC(0-Tlast) were 3.32 h.ng/ml (test patch) and 3.81 h.ng/ml (reference patch). The maximum plasma levels were 0.35 ng/ml and 0.41 ng/ml for the test and reference preparation, reached after 6.4 h and after 7.86 h, respectively. The statistical comparison (ANOVA, confidence intervals) showed bioequivalence between both patches concerning the metabolites investigated. The typical side effects known after nitrate therapy also occurred in the course of this study.

Administration, Cutaneous↗

Transdermal testosterone therapy in the treatment of male hypogonadism.

Five hypogonadal men were treated with transdermal testosterone therapy, using a testosterone patch applied to the scrotal skin. Daily application of the patch, which contained 10 mg testosterone, produced an increase in serum testosterone concentrations from a pretreatment value of 45 +/- 12 (+/- SE; 1.5 +/- 0.4) to 436 +/- 80 ng/dL (15.1 +/- 2.8 nmol/L; P less than 0.001) after 4 weeks of treatment. Normal serum testosterone concentrations were achieved in all men after 6-8 weeks of therapy and were maintained during continued long term therapy for 9-12 months with a patch containing 15 mg testosterone. All men reported a subjective increase in libido and sexual function during therapy, and three men preferred it to testosterone injections. The serum testosterone and estradiol levels did not rise above the normal adult male range at any time during therapy. However, elevated serum dihydrotestosterone (DHT) concentrations occurred during treatment; the pretreatment DHT concentration was 95 +/- 3 ng/dL (3.3 +/- 0.1 nmol/L), and it increased to 228 +/- 40 ng/dL (7.8 +/- 1.4 nmol/L) after 4 weeks of treatment and remained elevated thereafter. The individual mean DHT to testosterone ratio increased from a pretreatment value of 0.2 (range, 0.1-0.3) to 0.6 (range, 0.4-0.7) after 2 weeks of therapy and remained high thereafter. Comparison of the serum DHT levels in patients during therapy with those in normal men who had similar testosterone concentrations [531 +/- 62 vs. 566 +/- 72 ng/dL (18.4 +/- 2.1 vs. 19.6 +/- 2.5 nmol/L); P greater than 0.05] revealed that the mean serum DHT concentration was significantly higher in the patients [315 +/- 69 vs. 87 +/- 6 ng/dL (10.8 +/- 2.4 vs. 2.9 +/- 0.2 nmol/L); P less than 0.001], as was the mean DHT to testosterone ratio [0.6 (range, 0.25- 1.1) vs. 0.16 (range, 0.09- 0.24); P less than 0.001]. The high serum DHT levels presumably were due to increased metabolism of testosterone to DHT by the 5 alpha-reductase in the scrotal skin. Serum 3 alpha-androstanediol glucuronide levels were not elevated in the patients. We conclude that transdermal testosterone therapy is an effective long term treatment for hypogonadism in men. It is, however, associated with high serum DHT levels, whose potential long term effects on the prostate and other tissues need to be investigated.

Administration, Cutaneous↗

Transdermal drug delivery system (TDDS) adhesion as a critical safety, efficacy and quality attribute.

Transdermal drug delivery systems (TDDS), also known as "patches," are dosage forms designed to deliver a therapeutically effective amount of drug across a patient's skin. The adhesive of the transdermal drug delivery system is critical to the safety, efficacy and quality of the product. In the Drug Quality Reporting System (DQRS), the United States Food and Drug Administration (FDA) has received numerous reports of "adhesion lacking" for transdermal drug delivery systems. This article provides an overview of types of transdermals, their anatomy, the role of adhesion, the possible adhesion failure modes and how adhesion can be measured. Excerpts from FDA reports on the lack of adhesion of transdermal system products are presented. Pros and cons of in vitro techniques, such as peel adhesion, tack and shear strength, in vivo techniques used to evaluate adhesive properties are discussed. To see a decrease in "adhesion lacking" reports, adhesion needs to become an important design parameter and suitable methods need to be available to assess quality and in vivo performance. This article provides a framework for further discussion and scientific work to improve transdermal adhesive performance.

Administration, Cutaneous↗

Transdermal estradiol reduces plasma myeloperoxidase levels without affecting the LDL resistance to oxidation or the LDL particle size.

OBJECTIVE: This study was designed to investigate the effects of different therapeutic range doses of transdermal estradiol (E(2)), alone or in combination with progesterone (P) or medroxyprogesterone acetate (MPA), on plasma lipoprotein levels and on three parameters related with LDL oxidizability, the resistance of LDL to oxidation by copper, the LDL particle size, and the myeloperoxidase levels. DESIGN: Thirty-five healthy postmenopausal women who had been amenorrheic for at least 1 year received two consecutive, 2-month doses of transdermal estrogen (25-microg and 50-microg E(2) patch). Thereafter, they were randomly assigned to receive a 2-month treatment of either a 100-microg E(2) patch or a 50-microg E(2) patch combined with P (300 mg/day) or MPA (5 mg/day) during the last 14 days. RESULTS: Neither transdermal E(2) alone nor transdermal E(2) plus progestogen modified the lipoprotein profile, the LDL resistance to oxidation, or the LDL particle size. However, all treatments similarly reduced the myeloperoxidase protein levels. CONCLUSIONS: Different dosages of transdermal E(2) within the therapeutic range were equally effective in reducing myeloperoxidase protein levels. The effect remained after addition of P or MPA in a sequential regime.

Administration, Cutaneous↗

[Changes in C-reactive protein levels induced by different application forms of estrogen replacement therapy].

BACKGROUND: C-reactive protein is one of the independent risk factors of cardiovascular diseases. The aim of study was to find changes of hsCRP levels during transdermal and oral application of estrogen replacement therapy. METHODS AND RESULTS: Two application ways were used for 12 weeks: oral estradiol 2 mg/day and transdermal estradiol 50 microg /day (7-day patches). 41 healthy women with average age 49 +/- 6 years were randomised into prospective cross-over designed study. The average level of hsCRP before therapy was 3.3 mg/l. Elevation on 4.8 mg/I after the oral therapy was significant (p = 0.05). Transdermal estrogene therapy did not induce any significant (p = 0.87) changes. Differences between oral and transdermal therapy were significant (p = 0.002). CONCLUSIONS: The transdermal application of the estrogene replacement therapy is more safety for a vessel wall from the view of hsCRP levels. Differences between transdermal and oral application way are apparent even in case of the early start of hormone replacement therapy.

Administration, Cutaneous↗

Dynamic and static components of mechanical hyperalgesia in human hairy skin.

The principle finding of the present study is that there are two types of mechanical hyperalgesia developing in human hairy skin following injurious stimuli. Mechanical hyperalgesia comprises a dynamic component (brush-evoked pain, allodynia) signalled by large myelinated afferents and a static component (hyperalgesia to pressure stimuli) signalled by unmyelinated afferents. While the static component is only found in the injured area, the dynamic component also extends into a halo of undamaged tissue surrounding the injury. The irritant chemicals, mustard oil or capsaicin, were applied transdermally in 20 subjects to a patch (2 x 2 cm) of hairy skin. Both substances evoked burning pain and hyperalgesia to mechanical stimuli. While stroking normal skin with a cotton bud was perceived only as touch prior to chemical stimulation, there was a distinctly unpleasant sensation afterwards. This component of mechanical hyperalgesia persisted for at least 30 min and was present in the skin exposed to the irritants (primary hyperalgesia) as well as in a zone of untreated skin surrounding the injury (secondary hyperalgesia) measuring 38 +/- 4 cm2 after capsaicin. Pressure pain thresholds dropped to 55 +/- 8% of baseline level after mustard oil and to 46 +/- 9% after capsaicin. However, this drop of thresholds was short-lived, lasting 5 min following mustard oil but persisting more than 30 min following capsaicin treatment. The reduction of pressure pain thresholds was only observed for treated skin areas, but not in the surrounding undamaged tissue from where brush-evoked pain could be evoked. When pressure pain thresholds were lowered, the pain had a burning quality which differed distinctly from the quality of brush-evoked pain. On-going burning pain and both types of mechanical hyperalgesia were critically temperature dependent. Mildly cooling the skin provided instant relief from on-going pain, abolished brush-evoked pain and normalized pressure pain thresholds. Rewarming resulted in a reappearance of on-going pain and hyperalgesia. The effect of a nerve compression block of the superficial radial nerve on these sensations was tested in 14 experiments. When the ability to perceive light touch had been abolished, there was also no touch-evoked pain, indicating that this component of mechanical hyperalgesia is mediated by large-diameter primary afferents. At a later stage of the block when the subjects' ability to perceive cold stimuli had also been lost, application of cool stimuli still eliminated on-going burning pain, suggesting that pain relief afforded by cooling the skin acts at the peripheral receptor level and not by central masking.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

Eosinophilic pustular eruption associated with transdermal fentanyl.

A 70-year-old man developed a widespread eruption of sterile pustules on normal skin, mainly on the trunk, face and base of the limbs, 2 days after application of a fentanyl-transdermal therapeutic system (fentanyl-TTS) patch. The eruption was not accompanied by fever. The main histopathological finding was an intraepidermal pustule filled almost exclusively with eosinophils. Suspension of the fentanyl-TTS led to rapid and definitive spontaneous regression of the pustules in about 10 days. A similar pustular reaction related temporally to fentanyl-TTS administration had appeared several weeks before the current eruption.

Administration, Cutaneous↗

Effect of pre-treatment with nicotine patch on withdrawal symptoms and abstinence rates in smokers subsequently quitting with the nicotine patch: a randomized controlled trial.

AIMS: To determine whether 2-week pre-treatment with transdermal nicotine influences withdrawal symptoms or success rate of subsequent smoking cessation using nicotine patches. DESIGN: Randomized controlled trial. SETTING: Smoking cessation clinic. PARTICIPANTS: Healthy smokers (n = 200, 45% female) were allocated randomly to either active nicotine-patch (AP, 15 mg daily, n = 100) or placebo-patch (PP, n = 100) pre-treatment. Baseline characteristics were well balanced except for daily cigarette consumption: mean (+/- SD) 23.1 (8) and 26.4 (11) for AP and PP groups, respectively (P = 0.021). INTERVENTION: At the screening visit (-2 weeks) subjects were counselled and started pre-treatment with daily patches (AP or PP). From the quit date (week 0) onwards all subjects received active nicotine patches for 12 weeks (15 mg daily for 8 weeks, 10 and 5 mg daily for 2 weeks each) and counselling. MEASUREMENTS: Follow-up visits included measurement of exhaled carbon monoxide at the quit date, 2, 6, 10 and 26 weeks. Subjects documented daily cigarette consumption and severity of withdrawal symptoms (Wisconsin scale) from -2 weeks to week 2. Outcome measures were withdrawal symptoms composite score and abstinence rates. FINDINGS: There was no significant difference in withdrawal symptoms, but more subjects in the AP group were smoke-free during the 6-month study period. Overall sustained abstinence was documented in 17% of subjects at 6 months; 22% and 12% for AP and PP, respectively (P = 0.03). Retrospective subgroup analysis showed for subjects smoking >16 cigarettes/day sustained cessation rates were 22% and 9% for AP and PP, respectively (P = 0.01). No difference in adverse event rates was observed. CONCLUSIONS: Nicotine patch pre-treatment before cessation did not reduce early withdrawal symptoms but increased sustained abstinence rates at 6 months. The nicotine pre-treatment was equally effective in light and heavy smokers.

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Dihydroetorphine: a potent analgesic: pharmacology, toxicology, pharmacokinetics, and clinical effects.

Dihydroetorphine (DHE) is one of the strongest analgesic opioid alkaloids known; it is 1000 to 12000 times more potent than morphine. Several in vitro and in vivo studies have shown that DHE is a selective mu-opioid receptor (OP(3)) agonist that also binds and activates all human recombinant mu-, delta-, and kappa-opioid receptors (OP(3), OP(1), and OP(2)). The onset of the analgesic effect of DHE in rodents is rapid, 5 to 15 min after parenteral administration; the duration of action is short, the analgesic effect disappears within 120 min after administration. By oral administration much higher doses of DHE are required to produce analgesic effects. These characteristics are accounted for by the pharmacokinetic properties of DHE in the rat, namely, by rapid distribution of DHE from the injection site to the brain and rapid metabolism by glucuronidation in the gut and liver followed by elimination into the bile. Continuous infusion and repeated administration of DHE lead to the development of tolerance to analgesia, physical dependence, and a rewarding effect in normal rats but not in animals with formalin-induced inflammation. Although formalin-induced inflammation is only one type of pain stimulus, these findings suggest that DHE addiction would be observed only in the case of pain-free conditions. Clinical reports in China show that sublingual doses of DHE, 20 to 180 microg, produce a potent analgesic effect with only mild side effects, including dizziness, somnolence, nausea, vomiting, constipation, and shortness of breath. To improve the short-lasting effect following sublingual administration, transdermal delivery of DHE via a patch has been investigated. The patch formulation of DHE produces continuous analgesic effect with minimal physical dependence and rewarding effect in rats suffering from chronic pain. This patch formulation, which is very suitable for DHE, may be viable for the treatment of severe pain and is likely to improve patients' quality of life.

Administration, Cutaneous↗