Absorption, Metabolism, and Excretion of the Ephedrines in Man II

Wilkinson, G. R.; Beckett, A. H.

doi:10.1002/jps.2600571122

Cited by 55 publications

(38 citation statements)

References 7 publications

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“…(c) Acute and chronic compound tablet studies (Tables 3 and 4 (Wilkinson & Beckett, 1968b (Tables 14) are rough estimates only (see Appendix). However, the conclusion that the lag time, absorption rate constant and time of peak concentration are not significantly different whether the ephedrine is in solution or in tablet form is compatible with the reported rapid tablet disintegration and high drug solubility (see above), i.e.…”

Section: Resultsmentioning

confidence: 99%

“…The pharmacokinetics of ephedrine in man have been deduced from urinary measurement made in normal subjects under controlled conditions (Wilkinson & Beckett, 1968a;Welling, Lee, Patel, Walker & Wagner, 1971). A specific assay has been developed (Pickup & Paterson, 1974) in order to monitor plasma levels and study the pharmacokinetics of ephedrine following oral dosing with ephedrine in asthmatic patients.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The pharmacokinetics of ephedrine after oral dosage in asthmatics receiving acute and chronic treatment.

Pickup¹,

May²,

Ssendagire³

et al. 1976

Brit J Clinical Pharma

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1 Ephedrine plasma levels have been measured in ten asthmatic patients given a singel dose of ephedrine hydrochloride (22 mg) along and in combination with theophylline and a barbiturate. 2 Pharmacokinetic assessment of the data indicated no significant intra‐subject changes in kinetic parameters before or after chronic treatment with ephedrine HCl (11 mg three times a day) alone or in combination. 3 Tolerance to these therapeutic doses, if it occurs, is therefore not disposition‐ related but rather to pharmacodynamic changes.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The pharmacokinetics of ephedrine after oral dosage in asthmatics receiving acute and chronic treatment.

Pickup¹,

May²,

Ssendagire³

et al. 1976

Brit J Clinical Pharma

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“…However, recovery is partially dependent on urinary pH. In alkaline urine the increased reabsorption would result in prolonged retention of drug in the body, thus allowing more extensive metabolism to occur [20]. However, Lai et al [18] found that the total amount of pseudoephedrine excreted was independent of urinary pH, probably because the quantity of metabolite excreted is too small (~1% of the dose) for any changes to be detected within the narrow range of urinary pH studied (5.7-6.5).…”

Section: Discussionmentioning

confidence: 99%

Elimination of ephedrines in urine following multiple dosing: the consequences for athletes, in relation to doping control

Chester

Mottram

Reilly

et al. 2003

Brit J Clinical Pharma

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AimsTo study the elimination of ephedrines with reference to the International Olympic Committee (IOC) doping control cut-off levels, following multiple dosing of over-thecounter decongestant preparations. MethodsA double-blind study was performed in which 16 healthy male volunteers were administered either pseudoephedrine or phenylpropanolamine in ma ximal recommended therapeutic doses over a 36-h period. Urine was collected every two hours between 08:00 and 24:00 h and at 04:00 h throughout the testing period of three days. Urine drug levels were quantified using high performance liquid chromatography. Side-effects were assessed, including heart rate and blood pressure, every four hours between 08:00 and 20:00 h. ResultsMean (95% CI) total phenylpropanolamine and pseudoephedrine eliminated unchanged was 75 (88, 61) and 81 (92, 71)%, respectively. Maximum urine concentrations of phenylpropanolamine and pseudoephedrine were 112.1 (164.2, 59.9) and 148.5 (215.0, 82.1) mg.l -1 , respectively. A peak in drug urine concentration occurred four hours following the final dose. There were no adverse cardiovascular effects and only mild CNS stimulation was evident. ConclusionsFollowing therapeutic, multiple dosing, drug levels remain above the IOC cut-off levels for a minimum of 6 h and 16 h following final doses of phenylpropanolamine and pseudoephedrine, respectively. Athletes require informed advice on this from their healthcare professionals.

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“…In the same study, no significant interaction between (-)-ephedrine and caffeine was observed. When considered as a pure compound, the absorption of oral ephedrine is reported to be complete in humans (Wilkinson and Beckett 1968a) and pharmacokinetic studies revealed a large volume of distribution including transfer of ephedrine across the placenta and into maternal milk (Hughes et al, 1985). Furthermore, Berlin et al (2001) demonstrated that the maximal plasma ephedrine concentration (Cmax) and areas under the curves for up to 8 hours were proportional to the doses.…”

Section: Discussionmentioning

confidence: 99%

“…Pharmacokinetic studies of ephedrine, norephedrine, pseudoephedrine and methylephedrine in humans Wilkinson and Beckett (1968a) demonstrated that absorption of oral ephedrine was complete within 2 to 2.5 hours following oral administration of 25 mg ephedrine in three subjects. In this study, the kinetic parameters of absorption, metabolism and excretion of (-)-ephedrine, (-)-norephedrine and (-)-methylephedrine were calculated using pharmacokinetic compartment models.…”

Section: Pharmacokinetic Studies Of Pseudoephedrine In Animalsmentioning

confidence: 99%

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2013

EFSA Journal

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The ANS Panel provides a scientific opinion evaluating the safety in use of Ephedra herb and its preparations originating from Ephedra species when used in food, e.g. in food supplements. Ephedra species contain alkaloids of biological relevance: ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine (cathine), methylephedrine and methylpseudoephedrine. They have sympathomimetic activity and some of them are also used as active ingredients in medicinal products for which adverse effects are described. The use of Ephedra herb in food supplements is prohibited in several European countries, however food supplements containing Ephedra herb, also in combination with caffeine, are offered for sale via the internet. The Panel reviewed the available scientific data on a possible association between the intake of Ephedra herb, its preparations or its alkaloids and potential harmful effects on health. There is wide variation in the concentration of the individual ephedra alkaloids in different Ephedra species and in their preparations for use in food. No adequately specified individual preparations of Ephedra herb are known for which sufficient toxicological data for hazard characterisation exist. Due to the absence of adequate data on genotoxicity, short-term, long-term and reproductive and developmental toxicity the Panel could not provide advice on a daily intake of Ephedra herb and its preparations that do not give rise to concerns about harmful effects to health. Ephedra herb and its preparations in food supplements may result in exposure to total ephedra alkaloids or ephedrine which falls within or may exceed the therapeutic dose ranges for the individual ephedra alkaloids or ephedrine, respectively, in medicinal products. Such an exposure could lead to severe adverse effects, which may be enhanced by the combination with caffeine. The Panel concluded that Ephedra herb and its preparations containing ephedra alkaloids used as food supplements were of significant safety concern at the estimated use levels. In particular, EFSA was requested to review the existing scientific data on the possible link between the intake of Ephedra species and harmful effects on health, and to provide advice on a tolerable upper intake level (UL) for Ephedra species for the general population, and as appropriate, for vulnerable subgroups of the population. In the absence of a tolerable upper intake level, EFSA was asked to provide advice on a daily intake of Ephedra species that does not give rise to concerns about harmful effects to health.The risk assessment was performed by the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS Panel) in accordance with the 2009 EFSA Guidance on safety assessment of botanicals and botanical preparations intended for use as ingredients in food supplements.In addressing the Terms of Reference of this request, the ANS Panel noted that the term -tolerable upper intake level‖, was used by EFSA so far only for nutrients, such as vitamins or minerals, to describe the maximum ...

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Absorption, Metabolism, and Excretion of the Ephedrines in Man II

Cited by 55 publications

References 7 publications

The pharmacokinetics of ephedrine after oral dosage in asthmatics receiving acute and chronic treatment.

The pharmacokinetics of ephedrine after oral dosage in asthmatics receiving acute and chronic treatment.

Elimination of ephedrines in urine following multiple dosing: the consequences for athletes, in relation to doping control

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