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Pharmacokinetics and relative bioavailability of cyclobarbital calcium in man after oral administration


The pharmacokinetics and relative bioavailability of cyclobarbital calcium have been studied after oral administration of Phanodorm, of tablets according to the Formularium Nederlandse Apothekers (1968; FNA), and an aqueous solution. Six healthy volunteers participated in the investigation on three occasions and each received the three preparations. The dose administered was 300 mg cyclobarbital calcium. Plasma concentrations of cyclobarbital were determined at regular intervals. Absorption from the three preparations was rapid and was faster from the solution. Peak concentrations were usually attained within 1 h. The elimination of cyclobarbital could be described by a single first-order process with an average half-life of 11.6 h (range 8 – 17 h). There was little intra-subject variation of the half-life. Relative bioavailability for each volunteer was estimated by comparing the areas under the plasma concentration curves. The FNA-tablets and Phanodorm exhibited similar bioavailability, whereas the average bioavailability of the solution was 78% of that of FNA-tablets; the reason for this unexpected finding is unknown. It was concluded that cyclobarbital cannot be regarded as a uniformly suitable drug for the treatment of insomnia. The long half-life that was apparent in some of the volunteers (15 – 17 h) creates a substantial risk of residual effects on the following morning. In principle, however, the calcium salt of cyclobarbital may be used for induction of sleep, because of its rapid absorption.

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  1. Åhlander, S.: Svensk farm. T.60 249 (1956); cited by: Martindale, The Extra Pharmacopoeia, 26th ed., p. 902. London: The Pharmaceutical Press 1972

  2. Benet, L.Z.: Biopharmaceutics as a basis for the design of drug products. In: Drug design, Vol. IV, Chapter 1 (ed. E.J. Ariens), pp. 1–35, New York: Academic Press 1973

  3. Breimer, D.D., de Boer, A.G.: Pharmacokinetics and relative bioavailability of heptabarbital and heptabarbital sodium after oral administration to man. Europ. J. clin. Pharmacol.9 169–178 (1975)

  4. Breimer, D.D., van Rossum, J.M.: Rapid and sensitive gas chromatographic determination of hexobarbital in plasma of man using a nitrogen detector. J. Chromatogr.88 235–243 (1974)

  5. Brilmayer, H., Loennecken, S.J.: Die Eliminationsgeschwindigkeit von Barbiturat aus dem Blut akut intoxizierter Patienten. Arch. int. Pharmacodyn. Ther.84 137–146 (1962)

  6. Brochmann-Hanssen, E., Oke, T.O.: Gas chromatography of barbiturates, phenolic alkaloids and xanthine bases: flash-heater methylation by means of trimethyl-anilinium hydroxide. J. pharm. Sci.58 370–371 (1969)

  7. Dost, F.H.: Grundlagen der Pharmakokinetik. Stuttgart: Georg Thieme Verlag 1968

  8. Ehrnebo, M., Agurell, S., Boréus, L.O.: Gas chromatographic determination of therapeutic levels of amobarbital and pentobarbital in plasma. Europ. J. clin. Pharmacol.4 191–195 (1972)

  9. Fastier, F.N.: A comparison of the hypnotics Doriden and Nembutal. N.Z. med. J.57 171–175 (1958)

  10. Formularium Nederlandse Apothekers: Tabulae Cyclobarbitali, p. F 30. Koninklijke Nederlandse Maatschappij ter bevordering der Pharmacie, 's — Gravenhage 1968

  11. Gilette, J.R.: Factors affecting drug metabolism in man. Ann. N.Y. Acad. Sci.179 43–66 (1971)

  12. Guidelines for Biopharmaceutical Studies in Man. Washington D.C., U.S.A.: Amer. Pharmaceutical Ass., 1972

  13. Hinton, J.M.: A comparison of the effects of six barbiturates and a placebo on insomnia and motility in psychiatric patients. Brit. J. Pharmacol.20 319–325 (1963)

  14. Itil, T.: Die Problematik der Schlafstörungen und deren Beeinflussung. Arzneimittel-Forsch.12 399–407 (1962)

  15. Janke, W., Schmatzer, E.: Experimental psychologische Untersuchungen zur Wirkung einer Prothipendyl-Cyclobarbital-Calcium-Kombination im Vergleich zu Cyclobarbital-Calcium und Placebo. Arzneimittel-Forsch.12 1031–1036 (1962)

  16. Martindale: The Extra Pharmacopoeia, 26th ed., p. 891. London: The Pharmaceutical Press 1972

  17. Parsons, T.W., Thomson, T.J.: Methaqualone as a hypnotic. Brit. med. J.1961 I 171–173

  18. Rushbrooke, M., Wilson, E.S.B., Acland, J.D., Wilsin, G.M.: Clinical trial of Doriden, a new hypnotic. With note on use of ranking methods in assessing therapeutic effect. Brit. med. J.1956 I 139–142

  19. Wagner, J.G.: Biopharmaceutics and Relevant Pharmacokinetics. Hamilton: Drug Intelligence Publications 1971

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Breimer, D.D., Winten, M.A.C.M. Pharmacokinetics and relative bioavailability of cyclobarbital calcium in man after oral administration. Eur J Clin Pharmacol 9, 443–450 (1976). https://doi.org/10.1007/BF00606563

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Key words

  • Cyclobarbital calcium
  • pharmacokinetics
  • plasma concentration
  • relative bioavailability
  • oral administration