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Plasma cathinone levels following chewing khat leaves (Catha edulis Forsk.)
Journal of Ethnopharmacology 49 (1995) 11l-1 13
ELSEVIER
Short communication
Plasma cathinone levels following chewing khat leaves (Catha edulis Forsk.) J.M. Halket*a7b, Z. KarasuC, I.M. Murray-LyonC aBioanalytical Unit. Bernhard Baron Memorial Research Laboratories, 339 Goldhawk Road, London W6 OXG, UK bDepartment of Chemr’cal Pathology, Charing Cross and Westminster Medical School, St. Dunstan’s Road, London W6, UK ‘Department
of Gastroenterology,
Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK
Retived 3 December 1994, revision received 25 July 1995; accepted 25 August 1995
Keywords: Plasma; Cathinone; Khat; Drugs; HPLC; GUMS
1. Introduction The leaves of the Khat plant (Cutha edulis Forsk., Celastraceae) are widely chewed in Yemen and East Africa for their central stimulant properties. Khat is legally available in the UK. It is thought that the ;principal pharmacologically active component is the amphetamine-like alkaloid S-(-)-cathinone (cathinone; Kalix, 1992; Fig. 1). Cathinone has belen measured in spiked rabbit and human plasma (Morad et al., 1989) and in human plasma following ingestion of the pure alkaloid (Brenneisen et al., 1991) and standardized khat leaves (Widler et al., 1994). The present study reports blood levels in five subjects after chewing the natural leaf.
50-55 kg; three males, 70-75 kg) aged between 21 and 30 years were studied in the fasting state. None had chewed Khat before. Khat leaves freshly imported by air from Ethiopia were chewed (approx. 60 g per subject) for 1 h and care was taken not to swallow the residue. The cathinone content of the leaves was estimated to be approx. 0.9 mg/g fresh weight by gas chromatography/mass spectrometry (CC/MS) using amphetamine as the internal standard. The method will be detailed in
2. Materials and methods Five healthy adult individuals (two females, Corresponding author.
??
S(+)-AMPHETAMINE
S(-)-CATHINONE
Fig. I. Structures of amphetamine and cathinone.
0378-8741/95/$09.50 0 1995 Elsevier Science Ireland Ltd. All rights reserved SSDI 0378-8741(95)01306-X
J. M. Halket et al. /Journal of Ethnopharmacology 49 (1995) I1 1-I 13
112
temperature program: 220” (3 min) - lO”/min 280”, Hewlett-Packard 5970B Mass Selective Detector). The mass spectrum and retention time were compared with those of an authentic cathinone derivative.
a further communication. The dosage of cathinone ranged from 0.8-l mg/kg body weight. Leaves were frozen at -20°C for future reference. Blood was taken at time 0, 30, 60 and 90 min after commencement of chewing, and at 3.5 and 1.5 h and also at 24 h in two subjects. Plasma was spun off immediately and the sample stored frozen at -20°C. The project was approved by the Charing Cross Hospital Ethics Committee. Plasma was extracted and analysed by high performance liquid chromatography (HPLC) and CC/MS, essentially according to a published method (Brenneisen et al., 1991). Briefly 2 ml samples were spiked with amphetamine as internal standard, extracted on solid phase cartridges (Baker-lo, CN) and analysed by reverse phase HPLC (Waters 481 detector 200 nm, in place of diode-array). The presence of cathinone in the plasma samples was confirmed by collection of HPLC fractions, derivatization with (S)-(-)-Ntrifluoroacetylprolyl chloride (Sigma, St. Louis, USA) and CC/MS (Hewlett-Packard 5890 Series II gas chromatograph, 25 m x 0.22 mm i.d. fused silica capillary column, HP-l stationary phase,
3. Results Plasma concentration-time curves for the live subjects are shown in Fig. 2. Cathinone is barely detected with levels of about 20 ng/ml at 0.5 and 7.5 h after commencement of chewing the Khat leaves. Peak plasma levels are attained after about 1.5-3.5 h and maximum levels in the individuals range from 41 to 141 ng/ml (mean 83 ng/ml). 4. Discussion The plasma levels of cathinone determined in our study in which khat leaves were chewed, are similar to those described by Brenneisen et al. (1991) in six subjects after ingesting 0.5 mgkilo of pure alkaloid in a gelatine capsule. However, whereas in that study the maximum cathinone
160 Plasma Cathinone 140
0
1
2
3
4
5
6
7
Time (h) Fig. 2. Concentration-time
curves for plasma cathinone
in five subjects after chewing khat leaves.
7.5
24
J.M. Halket et al. /Journal of Ethnopharmacology 49 (1995) Ill-II3
concentrations were achieved at around 1 h, in the present study, the pea.k levels are reached later, at 1.5-3.5 h. This presumably reflects the slow release of the alkaloid from the plant during chewing. Blood levels after chewing for 1 h are declining rapidly by 7.5 h and undetectable at 24 h in the two subjects #studied. After completion of the present work, plasma time-concentration data were reported by Widler et al. (1994) in subjects following chewing of standardized leaves and the present data support these results. Cathinone is responsible for a wide range of sympathomimetic effects in the body (Brenneisen et al., 1990; Kalix, 1992) and we are currently correlating cardiovascular, gastrointestinal (Gunaid et al., 1995) and urodynamic (Nasher et al., 1995) changes in healthy volunteers with cathinone blood levels.
113
References Brenneisen, R., Mathys, K., Geisshiisler, S., Fisch, H.-U., Koelbing, U. and Kalix, P. (1991) Determination of S-(-)cathinone and its main metabolite R,S-(-)-norephedrine in human plasma by high-performance liquid chromatography and photodiode array detection. Journal of Liquid Chromatography 14, 21 l-286. Brenneisen, R., Fisch, H.-U., Koelbing, U., Geisshiisler, S. and Kalix, P. (1990) Amphetamine-like effects in humans of the khat alkaloid, cathinone. British Journal of Clinical Pharmacology 30, 825-828.
Gunaid, A.A., Sumairi, A.A., Shidrawi, R.G., Al-Hanaki, A., Al-Haimi, M., Al-Absi, M., Al-Hureibi, M.A., Qirbi, A.A., Al-Awlagi, S., El-Guneid, A.M., Shousha, S. and MurrayLyon, I.M. (1995) Gesophageal and gastric cancer in the Republic of Yemen. British Journal of Cancer 71,4&J-410. Kalix, P. (1992) Cathinone, a natural amphetamine. Pharmacology and Toxicology 70, 77-86.
Morad, A.M., Al-Meshal, I.A., Nasir, M. and El-Feraly, F.S. (1989) High-performance liquid chromatographic determination of (-)-cathinone in plasma. Chromatographia 27, 201-204.
Acknowledgements
The authors thank Ms. Anna Przyborowska for technical assistance and Mr. Ahmed Masood for supplying the khat.
Nasher, A.A., Qirbi, A.A., Ghafoor, M.A., Catterall, A., Thompson, A., Ramsay, J.W.A. and Murray-Lyon, I.M. (1995) Khat chewing and bladder neck dysfunction. A randomised controlled trial of crl-adrenergic blockade. British Journal of Urology 75, 597-598.
Widler, P., Mathys, K., Brenneisen, R., Kalix, P. and Fisch, H.-U. (1994) Pharmacodynamics and pharmacokinetics of khat: a controlled study. Clinical Pharmacology and Therapeutics 55, 556-562.
ELSEVIER
Short communication
Plasma cathinone levels following chewing khat leaves (Catha edulis Forsk.) J.M. Halket*a7b, Z. KarasuC, I.M. Murray-LyonC aBioanalytical Unit. Bernhard Baron Memorial Research Laboratories, 339 Goldhawk Road, London W6 OXG, UK bDepartment of Chemr’cal Pathology, Charing Cross and Westminster Medical School, St. Dunstan’s Road, London W6, UK ‘Department
of Gastroenterology,
Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK
Retived 3 December 1994, revision received 25 July 1995; accepted 25 August 1995
Keywords: Plasma; Cathinone; Khat; Drugs; HPLC; GUMS
1. Introduction The leaves of the Khat plant (Cutha edulis Forsk., Celastraceae) are widely chewed in Yemen and East Africa for their central stimulant properties. Khat is legally available in the UK. It is thought that the ;principal pharmacologically active component is the amphetamine-like alkaloid S-(-)-cathinone (cathinone; Kalix, 1992; Fig. 1). Cathinone has belen measured in spiked rabbit and human plasma (Morad et al., 1989) and in human plasma following ingestion of the pure alkaloid (Brenneisen et al., 1991) and standardized khat leaves (Widler et al., 1994). The present study reports blood levels in five subjects after chewing the natural leaf.
50-55 kg; three males, 70-75 kg) aged between 21 and 30 years were studied in the fasting state. None had chewed Khat before. Khat leaves freshly imported by air from Ethiopia were chewed (approx. 60 g per subject) for 1 h and care was taken not to swallow the residue. The cathinone content of the leaves was estimated to be approx. 0.9 mg/g fresh weight by gas chromatography/mass spectrometry (CC/MS) using amphetamine as the internal standard. The method will be detailed in
2. Materials and methods Five healthy adult individuals (two females, Corresponding author.
??
S(+)-AMPHETAMINE
S(-)-CATHINONE
Fig. I. Structures of amphetamine and cathinone.
0378-8741/95/$09.50 0 1995 Elsevier Science Ireland Ltd. All rights reserved SSDI 0378-8741(95)01306-X
J. M. Halket et al. /Journal of Ethnopharmacology 49 (1995) I1 1-I 13
112
temperature program: 220” (3 min) - lO”/min 280”, Hewlett-Packard 5970B Mass Selective Detector). The mass spectrum and retention time were compared with those of an authentic cathinone derivative.
a further communication. The dosage of cathinone ranged from 0.8-l mg/kg body weight. Leaves were frozen at -20°C for future reference. Blood was taken at time 0, 30, 60 and 90 min after commencement of chewing, and at 3.5 and 1.5 h and also at 24 h in two subjects. Plasma was spun off immediately and the sample stored frozen at -20°C. The project was approved by the Charing Cross Hospital Ethics Committee. Plasma was extracted and analysed by high performance liquid chromatography (HPLC) and CC/MS, essentially according to a published method (Brenneisen et al., 1991). Briefly 2 ml samples were spiked with amphetamine as internal standard, extracted on solid phase cartridges (Baker-lo, CN) and analysed by reverse phase HPLC (Waters 481 detector 200 nm, in place of diode-array). The presence of cathinone in the plasma samples was confirmed by collection of HPLC fractions, derivatization with (S)-(-)-Ntrifluoroacetylprolyl chloride (Sigma, St. Louis, USA) and CC/MS (Hewlett-Packard 5890 Series II gas chromatograph, 25 m x 0.22 mm i.d. fused silica capillary column, HP-l stationary phase,
3. Results Plasma concentration-time curves for the live subjects are shown in Fig. 2. Cathinone is barely detected with levels of about 20 ng/ml at 0.5 and 7.5 h after commencement of chewing the Khat leaves. Peak plasma levels are attained after about 1.5-3.5 h and maximum levels in the individuals range from 41 to 141 ng/ml (mean 83 ng/ml). 4. Discussion The plasma levels of cathinone determined in our study in which khat leaves were chewed, are similar to those described by Brenneisen et al. (1991) in six subjects after ingesting 0.5 mgkilo of pure alkaloid in a gelatine capsule. However, whereas in that study the maximum cathinone
160 Plasma Cathinone 140
0
1
2
3
4
5
6
7
Time (h) Fig. 2. Concentration-time
curves for plasma cathinone
in five subjects after chewing khat leaves.
7.5
24
J.M. Halket et al. /Journal of Ethnopharmacology 49 (1995) Ill-II3
concentrations were achieved at around 1 h, in the present study, the pea.k levels are reached later, at 1.5-3.5 h. This presumably reflects the slow release of the alkaloid from the plant during chewing. Blood levels after chewing for 1 h are declining rapidly by 7.5 h and undetectable at 24 h in the two subjects #studied. After completion of the present work, plasma time-concentration data were reported by Widler et al. (1994) in subjects following chewing of standardized leaves and the present data support these results. Cathinone is responsible for a wide range of sympathomimetic effects in the body (Brenneisen et al., 1990; Kalix, 1992) and we are currently correlating cardiovascular, gastrointestinal (Gunaid et al., 1995) and urodynamic (Nasher et al., 1995) changes in healthy volunteers with cathinone blood levels.
113
References Brenneisen, R., Mathys, K., Geisshiisler, S., Fisch, H.-U., Koelbing, U. and Kalix, P. (1991) Determination of S-(-)cathinone and its main metabolite R,S-(-)-norephedrine in human plasma by high-performance liquid chromatography and photodiode array detection. Journal of Liquid Chromatography 14, 21 l-286. Brenneisen, R., Fisch, H.-U., Koelbing, U., Geisshiisler, S. and Kalix, P. (1990) Amphetamine-like effects in humans of the khat alkaloid, cathinone. British Journal of Clinical Pharmacology 30, 825-828.
Gunaid, A.A., Sumairi, A.A., Shidrawi, R.G., Al-Hanaki, A., Al-Haimi, M., Al-Absi, M., Al-Hureibi, M.A., Qirbi, A.A., Al-Awlagi, S., El-Guneid, A.M., Shousha, S. and MurrayLyon, I.M. (1995) Gesophageal and gastric cancer in the Republic of Yemen. British Journal of Cancer 71,4&J-410. Kalix, P. (1992) Cathinone, a natural amphetamine. Pharmacology and Toxicology 70, 77-86.
Morad, A.M., Al-Meshal, I.A., Nasir, M. and El-Feraly, F.S. (1989) High-performance liquid chromatographic determination of (-)-cathinone in plasma. Chromatographia 27, 201-204.
Acknowledgements
The authors thank Ms. Anna Przyborowska for technical assistance and Mr. Ahmed Masood for supplying the khat.
Nasher, A.A., Qirbi, A.A., Ghafoor, M.A., Catterall, A., Thompson, A., Ramsay, J.W.A. and Murray-Lyon, I.M. (1995) Khat chewing and bladder neck dysfunction. A randomised controlled trial of crl-adrenergic blockade. British Journal of Urology 75, 597-598.
Widler, P., Mathys, K., Brenneisen, R., Kalix, P. and Fisch, H.-U. (1994) Pharmacodynamics and pharmacokinetics of khat: a controlled study. Clinical Pharmacology and Therapeutics 55, 556-562.