Summary
In four healthy subjects the intestinal absorption of levodopa (l-dopa) was investigated by measuring the plasma concentration of the amino acid following the administration of l-dopa at three different sites in the small intestine. In order to minimize presystemic clearance of l-dopa, the subjects were pretreated with the peripheral decarboxylase inhibitor benserazide 3×50 mg every 8 h on the previous day and 1×50 mg 2 h prior to administration of the l-dopa. L-dopa 100 mg dissolved in 0.05 N HCl and 50 mg benserazide dissolved in 0.05 N HCl were coadministered. Under these conditions no difference in tmax, cmax or AUC of l-dopa was observed between administration of the drug into the proximal or the distal part of duodenum, or into the upper part of jejunum. The results indicate that in healthy subjects, during inhibition of peripheral decarboxylase, the rate and extent of l-dopa absorption does not differ at any site in the upper small intestine.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Barbeau A (1974) The clinical physiology of side effects in long term l-dopa therapy. Adv Neurol 5: 347–365
Bianchine JR, Shaw GM (1976) Clinical pharmacokinetics of levodopa in Parkinson's disease. Clin Pharmacokinet 1: 313–338
Birkmayer W, Danielcyk W, Neunayer E, Riederer P (1973) L-dopa level in plasma, primary condition for the kinetic effect. J Neurotrans 34: 133–143
Da Prada M, Ketteler R, Haefely W (1979) Effect of benserazide and carbidopa on the concentration of endogenous dopa in human and rat plasma. Naunyn Schmiedebergs Arch Pharmacol 307: R61
Doller HJ, Connor JD, Lock DR, Sloviter RS, Dvorchik BH, Vesell ES (1978) Levodopa pharmacokinetics: Alteration after benserazide, a decarboxylase inhibitor. Drug Metab Dispos 6: 164–168
Dunner DL, Brodie HKH, Goodwin FK (1971) Plasma response to levodopa administration in man: Effects of a peripheral decarboxylase inhibitor. Clin Pharmacol Ther 12: 212–217
Evans MA, Triggs EJ, Broe GA, Saines N (1980) Systemic availability of orally administered l-dopa in the elderly Parkinsonian patient. Eur J Clin Pharmacol 17: 215–221
Gibaldi M, Perrier D (1975) Pharmacokinetics. Marcel Dekker, New York, p 239–296
Kutt H, McDowell FH (1980) Neurological diseases. In: Avery GS (ed) Drug treatment, 2nd edition, Adis Press, Sydney New York, p 1010–1056
Mearrick PT, Wade DN, Birkett DJ, Morris J (1974) Metoclopramide, gastric emptying and l-dopa absorption. Aust N Z J Med 4: 144–148
Mearrick PT, Graham GG, Wade DN (1975) The role of the liver in the clearance of l-dopa from plasma. J Pharmacokinet Biopharm 3: 13–23
Sasahara K, Nitanai T, Habara T, Morioka T, Nakajima E (1980) Dosage form design for improvement of bioavailability of levodopa II: Bioavailability of marked levodopa preparations in dogs and Parkinsonian patients. J Pharm Sci 69: 261–265
Sasahara K, Nitanai T, Habara T, Kojima T, Kawahara K, Morioka T, Nakajima E (1981) Dosage form design for improvement of bioavailability of levodopa IV: Possible causes of low bioavailability of oral levodopa in dogs. J Pharm Sci 70: 730–733
Siegel S (1956) Nonparametric statistics. McGraw-Hill, New York, p 166–172
Papavasiliou PS, Cotzias GC, Düby SE, Steck AJ, Fehling C, Bell MA (1972) Levodopa in Parkinsonism: Potentiation of central effects with a peripheral inhibitor. N Engl J Med 286: 8–14
Pinder RM, Brogden RN, Sawyer PR, Speight TM, Avery GS (1976) Levodopa and decarboxylase inhibitors: A review of their clinical pharmacology and use in the treatment of Parkinsonism. Drugs 11: 329–377
Wade DN, Mearrick PT, Morris JL (1973) Active transport of l-dopa in the intestine. Nature 242: 463–465
Wade DN, Mearrick PT, Birkett DJ, Morris JL (1974) Variability of l-dopa absorption in man. Aust N Z J Med 4: 138–143
Zürcher G, Da Prada M (1979) Radioenzymatic assay of femtomole concentrations of dopa in tissues and body fluids. J Neurochem 33: 631–639
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Gundert-Remy, U., Hildebrandt, R., Stiehl, A. et al. Intestinal absorption of levodopa in man. Eur J Clin Pharmacol 25, 69–72 (1983). https://doi.org/10.1007/BF00544017
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00544017