First Draft Prepared by
    Dr. William C. Keller
    Food and Drug Administration
    Rockville, Maryland, USA


    Dr D.M. Pugh
    University College
    Dublin, Ireland


         Propionylpromazine (PPZ) is a crystalline slightly yellow
    powder with a melting point around 70 °C. It is a neuroleptic
    phenothiazine derivative. Other similar drugs with wide veterinary
    use include promazine and chlorpromazine. In the dog, PPZ is two to
    four times more potent than chlorpromazine, but is in all other
    respects clinically indistinguishable. In veterinary medicine the
    hydrochloride salt is used as a 1% aqueous injectable solution.
    Phenothiazine neuroleptic compounds are most often used as
    antiemetics, antipruritics, and as premedication for anęsthesia in
    veterinary medicine.

         PPZ was in common use in veterinary practice in the 1950s and
    1960s. PPZ is of interest to JECFA because of the illicit use at
    pharmacological dosage (< 1 mg/kg i.m.) in the immediate
    pre-slaughter period. PPZ is used to lessen weight loss, trauma,
    disease, aggression and/or the prevalence of pale, soft exudative
    (PSE) pork produced from stress-susceptible animals (Zacharias,
    1975). This use of PPZ was reported as long ago as 1961 (Kaemmerer,
    1961); it has caused concern and stimulated efforts to identify
    resulting tissue residues (Haagsma, et al., 1988; Keukens and Aerts,

         PPZ is reportedly used widely in horse racing to alter
    performance, although approval for its use in horses was withdrawn
    in the US following reports that its use caused irreversible penile
    paralysis in stallions.

         PPZ has not been evaluated previously by the Expert Committee.

    Synonyms: Propiopromazine, Combelene, Tranvet, Tranvex

    FIGURE 1

    Molecular formula:         C20H24N2OS

    Molecular weight:          340.55

    Chemical name:             1[10[3-(dimethylamino)-propyl]-10H-pheno-


    2.1  Biochemical aspects

    2.1.1  Absorption, Distribution, and Excretion

         The comparative distribution and depletion of PPZ was studied
    in the rat and pig. Female Wistar rats and Landrace pigs were
    injected with PPZ. Resulting tissue levels are shown at Tables 1 and

        Table 1.  Propionylpromazine concentrations in tissues of the rat after i.v.
              administration of 4 mg propiopromazine phosphate per kg body weight

    Time after injection                    Propiopromazine concentration (µg/g)1

                                   Kidney                   Liver                  Brain

            0.2                   16.2 ± 4.8               1.3 ± 0.4              5.6 ± 1.3
            0.5                    9.9 ± 3.2               1.2 ± 0.2              5.4 ± 0.8
            1.0                    7.0 ± 3.0               1.1 ± 0.3              2.7 ± 0.4
            2.0                    3.3 ± 1.5               0.6 ± 0.2              0.6 ± 0.2

    1.  Mean standard deviation of four individual rats.

    Table 2.   Propionylpromazine concentrations in pig tissues at different times after
               i.m. injection of 0.5 mg of propiopromazine phosphate per kg body
               weight (approximately 50 mg per animal)

    Time after    Sex*                 Concentrations (ng/g)                  Quantity (mg)

                           Kidney    Liver     Brain      Diaphragm       Injection site

                  s        340        260       210         50          28.8
                  s        340        300       200         30          10.2
      2                                                                             21.6 ± 8.0**
                  b         90         80       210         70          24.0
                  b         90         70       130         50          23.6

    Table 2. cont'd

    Time after    Sex*                 Concentrations (ng/g)                  Quantity (mg)

                           Kidney    Liver     Brain      Diaphragm       Injection site

                  s        150        200       190         50          15.0
                  s        150        240       130         30          21.4
      8                                                                             19.3 ± 3.2**
                  b         50         80       190         60          18.5
                  b        110        170       180         60          22.1

                  s         50        240        40       < 10           4.6
                  s         40        370        50         10           7.4
     24                                                                             5.7 ± 2.6**
                  b         40        120        50         10           8.3
                  b         80        190       100         20           2.6

    Control       s        < 2       < 10      < 10       < 10          <0.001***
                  b        < 2       < 10      < 10       < 10          <0.001***

    *    s, Sows; b, castrated boars
    **   Mean ± standard deviation
    ***  Same site as in treated animals
         The investigators concluded there was a significant difference
    in the ratios of kidney and liver residue concentrations in rats and
    pigs, a potential sex-related difference in liver/kidney
    distribution in swine, and an apparent distribution to liver at 24
    hours in swine. All residues were in sub ppm concentration in pigs
    and by 24 hours the liver was the target organ (x = 230 ng/g), a
    concentration which differed little from that at two and eight hours
    post-dosing. Kidney, brain and diaphragm concentrations had fallen
    to about 25% of the 2 hour values by 24 hours. At 24 hours 10% to
    20% of the administered dose remained at the injection site,
    indicating a depot effect which can confuse interpretation of the
    time-concentration data. Nonetheless, the 24-hour muscle
    concentrations were at the limit of detection for this method.
    (Olling et al., 1981).

         Five pigs were dosed with PPZ at 0.5 mg base/kg body weight
    intramuscularly and killed at two and four hours afterwards.
    Residues in muscle, fat, kidney, liver, blood and urine were assayed
    for PPZ and its sulfoxide by GLC. Use of a protease was beneficial

    in increasing analytic yields from tissues, emphasizing the
    importance of binding to protein as a feature of the distribution
    phase of phenothiazine derivatives. The report stressed also the
    ease with which light and oxygen can cause molecular change in this
    group and, hence, analytical problems. No tissue concentration was
    in the ppm range other than injection site. Depot fat was richest in
    parent compound (< 367 µg/kg at 4 h), again a feature to be
    anticipated with this highly lipophilic drug. Injection site
    concentrations were in the trace to 863 µg/kg range five days after
    dosing. In no case did tissue PPZ sulfoxide concentrations exceed
    those of parent compound. In contrast, when urine was first
    subjected to ß-glucuronidase the sulfoxide metabolite almost always
    exceeded the concentration of PPZ itself. Detectable concentrations
    persisted for up to 48 hours in three pigs (Arneth, 1986).

         Other authors have described different analytical methods
    capable of detecting PPZ in pig kidney in the open literature:
    Keukens & Aerts (1989) used HPLC, Friedrich (1988) HPLC,
    Scheutwinkel-Reich et al. (1982) GC-MS, Van Ginkel et al. (1988) LC
    plus UV spectrum, Haagsma et al. (1988) 2-dimensional TLC. All the
    above studies but one (Haagsma et al.) were methodological
    evaluations using spiked tissue and yielded recoveries between 13%
    and 95% with detection limits between 1 and 25 ppb.

         Medicated pigs were dosed at recommended levels and slaughtered
    two, five and eight hours later. Six pigs were used, two were
    slaughtered at each interval and kidney, diaphragm, and injection
    site were sampled. Only diaphragm tissue sampled after eight hours
    yielded no detectable residue. Injection site tissues provided the
    highest concentration of PPZ (Haagsma et al. (1988).

         Several proprietary reports, all dating from 1977, report a
    satisfactory fluorometric method for pig tissue residue studies of
    PPZ and its sulfoxide (Putter, 1977), a study of PPZ concentration
    in plasma (Putter, et al 1977), and PPZ concentration in various
    tissues (Putter and Bauditz, 1977). Each reported concentrations
    following a single intramuscular injection of PPZ at 2 mg/kg. In
    plasma, trace concentrations were reached by 48 hours (n = 3), but
    in tissues had not been reached by 72 hours (n = 6). Liver was the
    target organ (88-119 µg/kg at 72 k). Urine was not studied.

    2.1.2  Biotransformation

         PPZ metabolites suitable for detection of illicit doping of
    racehorses were investigated in horse urine. Three metabolites were
    identified. The recommended metabolite for detection of doping was
    2-(1-hydroxypropyl)promazine sulfoxide (Dewey and Maylin, 1984). In

    a later paper (Park et al., 1989) the metabolism and
    pharmacokinetics of PPZ in horses were also studied. The parent and
    3 metabolites, 2-(1-hydroxy-propyl)promazine,
    2-(1-propenyl)promazine, and 7-hydroxyprop-ionylpromazine were
    identified in urine. The serum t was 5 hour.

    2.1.3  Effects on enzymes and other biochemical parameters

         The effects of PPZ and other tranquillizers on cerebrospinal
    fluid and serum constituents were studied in the anaesthetized dog.
    PPZ at 0.3 mg/kg decreased the concentration of urea N and Na+ in
    cerebrospinal fluid. PPZ decreased serum urea N, increased serum
    Ca++ and Cl-, and had no effect on glucose, creatinine,
    potassium, or inorganic phosphates in cerebrospinal fluid or serum.
    (Hassan et al., 1985a). The effects of PPZ and other tranquillizers
    on cerebrospinal fluid constituents were further studied in the
    anęsthetized dog at 0.6 mg/kg. PPZ lowered potassium levels
    significantly but had no other effect. (Hassan et al., 1985b)

         Serum and pituitary LH and FSH were reduced when 1.5 mg/kg PPZ
    was given to mature male rats i.p. daily for 2 weeks (Ibrahim et
    al., 1987).

    2.2  Toxicological studies

    2.2.1  Acute toxicity studies


            Species        Sex       Route          LD50 (mg/kg)     Reference

            Mouse          M&F       i.v.           38(35.7-40.5)    Silvestrini &
                                                                     Quadri (1970)
    2.2.2  Short-term studies

         No information available.

    2.2.3  Long-term/carcinogenicity studies

         No information available.

    2.2.4  Reproduction studies

         No information available

    2.2.7  Special studies on genotoxicity


    Test system     Test object         Concentration    Results     Reference

    Ames test       S. typhimurium      1 mg, 5 mg       Negative    Preiss et al.
                    TA 1535, 100,                                    (1983)
                    98, 1537, 1538
    2.3  Observations in humans

         There are no reports available from clinical studies of PPZ in
    humans. The structure of PPZ, shown in Figure 1, is almost identical
    to that of its structural isomer, propiomazine (Fig 2) (Booth,
    1988). The effects of propiomazine have been reported in humans for
    whom it is used as a tranquillizer and sleep-inducing agent. Its use
    is particularly common in Scandinavia, where it has been used for

    FIGURE 2

         Two recent clinical reports on the effects of propiomazine in
    humans are summarized below:

         The effects of propiomazine on sleep were studied in 10 healthy
    adult volunteers. The subjects received 25 mg propiomazine orally on
    5 consecutive nights. A decrease in sleep latency and suppression of
    REM sleep, and an increase in sleep quality were reported (Almqvist
    et al., 1987).

         In another study 25 mg of propiomazine was given orally to 40
    elderly subjects to study effect on sleep. Propiomazine was very
    effective in 20 normal subjects, and also increased the duration of
    sleep in psychogeriatric subjects (Viukari and Miettinen, 1984).


         There are no useful reports available from studies conducted to
    determine the no effect level for PPZ in animals.

         The manufacturer was unable to supply the Committee with data
    on the pharmacology and toxicology of propionylpromazine and the
    published literature has yielded relatively little information.
    However, the drug is of known efficacy in clinical use. Both pigs
    and horses are able to metabolize propionylpromazine, at least in
    part, but neither case was a full distribution, metabolism,
    elimination, or balance study available. A single value of 863 µg/kg
    has been recorded at the injection site in a pig 5 days after the
    intramuscular injection of 0.5 mg/kg of propionylpromazine. The drug
    binds extensively to tissue, and to proteins, and also accumulates
    in fatty tissues. In rats and pigs, the drug is able to enter the
    brain and, in dogs, has been shown to cause minor changes in
    cerebrospinal fluid and serum. The NOEL for these changes was
    0.6 mg/kg given intravenously.

         In rats, a reduction in the concentrations of pituitary
    gonadotrophins has been demonstrated in brain and serum following
    the daily intraperitoneal injection of propionylpromazine at
    1.5 mg/kg for 2 weeks.

         The intravenous LD50 of propionylpromazine in mice was
    38 mg/kg.

         In a 4-week study of groups of 5 female and 5 male rats exposed
    to propionylpromazine in the diet at 0, 60, 360, and 2160 mg/kg
    b.w./day, a decreased rate of weight gain was seen each week in both
    sexes at the highest dose and in females at 360 mg/kg b.w./day,
    which was associated with reduced feed intake. A reduction in
    ovarian weight in all treated females and a dose-dependent reduction
    in thyroid weight in males prevented the establishment of a NOEL in
    this study. Slight periportal fatty infiltration, which sometimes
    involved mid-zone and centrilobular hepatocytes, was seen in all
    treated animals and was greatest in the high-dose group.

         No short- or long-term studies, no systematic studies of the
    effects of the drug on reproduction, or of its teratogenicity,
    mutagenicity, carcinogenicity, or immunotoxicity, and no reports on
    its use in humans were available to the Committee. However, several
    studies have reported the presence of propionylpromazine in pig
    kidneys collected from abattoirs so that human exposure must
    therefore be presumed.


         The absence of information in several major areas of
    pharmacological and toxicological importance made it impossible for
    the Committee to establish an ADI for propionylpromazine. This is
    regrettable because the Committee was aware that propionylpromazine
    is used in circumstances in which the consumer will be exposed to
    residues that may be capable of exerting a pharmacological effect.


    ROOS, B. (1987) Effects of propiomazine on the EEG sleep of normal
    subjects.  Pharm and Toxicol., 61: 278-81.

    ARNETH, W. (1986) Untersuchungen zur Verteilung von Combelen und
    Combelen-Sulfoxid-Ruchstanden im Schwein.  Fleischwirtschaft,
    66(5): 922-925.

    BOOTH, N.H. (1988) Psychotropic agents. In:  Veterinary Pharmacology
     and Therapeutics. ed Booth and McDonald Iowa State University
    Press, Ames Iowa, 363-81.

    DEWEY, E.A. & MAYLIN, G.A. (1984) Analysis of propionylpromazine and
    its metabolites in horse urine.  Cornell Veterinarian, 74: 38-49.

    FRIEDRICH, A. (1988) Screening-Test zum qualiftativen Nachweis der
    gebrauchlichsten Transportprotektoren (Sedativa, Betablocker) mit
    Hilfe der Hochdruch flussigkeitschromatographie.  Tierarztliche
     Umschau., 43: 493-501.

    Van GINKEL, L.A., SCHWILLENS, P.L.W.J. & OLLING, M. (1989) Liquid
    chromatographic method with on-line UV spectrum identification and
    off-line thin layer chromatographic confirmation for the defection
    of tranquillisers and carazolol in pig kidneys.  Analytica Chemica
     Acta, 225: 137-146.

    HAAGSMA, N, BATHELT, E.R., ENGELSMA, J.W. (1988) Thin-layer
    chromatographic screening method for the tranquillizers azaperone,
    propiopromazine and carazolol in pig tissues.  J. Chromatography,
    436: 73-9.

    H.A. (1985a) Effect of some tranquilizers on cerebrospinal fluid and
    serum constituents in dogs,  Vet Med J., 33: 2, 199-209.

    HASSAN, A.B., EL-KHALIK, A.A., & ZAGHLOL, H.A. (1985b) Effect of
    some tranquilizers on cerebrospinal fluid (CSF) in dogs.  Egypt J.
     Vet Sci., 21(2): 279-86.

    IBRAHIM, S.S., EL-SADET, S.E. & ABOUL-ELA, A. (1987) Effects of some
    tranquilizers on the levels of gonadotropins and thyroid activity in
    mature male rats.  Vet Med J., 35(1): 129-37.

    KAEMMERER, K. (1961) Erfahrungen bei transportversuchen unter
    Combelen-Schutz.  Veterinarmedizinische Nachrichten, No. 2: 51-64.

    KEUKENS, H.J. & AERTS, M.M. (1989) Determination of residues of
    carazolol and a number of tranquillisers in swine kidney by high
    performance liquid chromatography with ultraviolet and fluorescence
    detection.  Journal of Chromatography, 464: 149-161.

    OLLING, M., STEPHANY, R.W. & RAUWS, A.G. (1981) The determination of
    propiopromazine in animal tissue.  Journal of Veterinary
     Pharmacology and Therapeutics, 4: 291-294.

    PARK, J., SHIN, Y.O. & CHOO, H.P. (1989) Metabolism and
    pharmacokinetic studies of propionylpromazine in horses.  Journal of
     Chromatography, 489: 313-321.

    PREISS A., SCHEUTWINKLE-REICH, M. & STAN, H.J. (1983) Mutagenic
    nature of tranquilizers used in animal fattening as revealed in the
     Salmonella/microsome test.  Fleischwirtschaft (abs), 63(2):

    PUTTER, J. (1977) Determination of Combelen and its sulphoxide in
    biological material. Unpublished Report (PHARMA REPORT No. 6733)
    from Bayer AG. Submitted to WHO by Bayer AG, Leverkusen, Germany.

    PUTTER, J., BAUDITZ, R., & DORN, H. (1977) Unpublished Report
    (PHARMA REPORT No. 6790) from Bayer AG. Submitted to WHO by Bayer
    AG, Leverkusen, Germany.

    PUTTER, J. & BAUDITZ, R. Combelen: Residue investigations in pigs.
    Unpublished Report (PHARMA REPORT No. 6840) from Bayer AG. Submitted
    to WHO by Bayer AG, Leverkusen, Germany.

    RAUWS, A.G. (1983) Tranquillisers in the transport of pigs destined
    for slaughter: a residue problem?  Tijdschrift Diergeneeskunde,
    108: 659-664.

    STAN, H.J. (1982) GC and GC-MS analysis of tranquillisers in meat.
     Fresenius Zeitung für Analytische Chemie, 311: 398-399.

    SILVESTRINI B., & QUADRI, E. (1970) Investigations on the
    specificity of the so-called analgesic activity of non-narcotic
    drugs.  European J. of Pharmacology, 12: 231-235.

    VIUKARI, M. & MIETTINEN, P. (1984) Diazepam, promethazine and
    propiomazine as hypnotics in elderly inpatients.
     Neuropsychobiology, 12: 134-7.

    ZACHARIAS, H. (1975) Sedation von Schlachtschweinen vor der Transort
    und die sich daraus ergebendedn veterinarmedizinischen, rechtlichen
    wie fleishhygienischen Fragen.  Tierartzliche Umschau, 30: 598-600.

    See Also:
       Toxicological Abbreviations