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Avian Pathology

ISSN: 0307-9457 (Print) 1465-3338 (Online) Journal homepage: http://www.tandfonline.com/loi/cavp20

Correlation of injection site damage and serum creatine kinase activity in turkeys following intramuscular and subcutaneous administration of norfloxacin nicotinate A. Nyska , M. Skolnick , G. Ziv & A. Gulkarov To cite this article: A. Nyska , M. Skolnick , G. Ziv & A. Gulkarov (1994) Correlation of injection site damage and serum creatine kinase activity in turkeys following intramuscular and subcutaneous administration of norfloxacin nicotinate, Avian Pathology, 23:4, 671-682, DOI: 10.1080/03079459408419036 To link to this article: http://dx.doi.org/10.1080/03079459408419036

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Avian Pathology (1994) 23, 671-682

Correlation of injection site damage and serum creatine kinase activity in turkeys following intramuscular and subcutaneous administration of norfloxacin nicotinate A. NYSKA1, M. SKOLNICK 2 , G. ZIV1 & A. GULKAROV3 1

Ministry of Agriculture, Kimron Veterinary Institute, P.O. Box 12, Bet-Dagan 50 250, 2Life Science Research Israel, Ness-Zional, and 3Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel

SUMMARY Turkeys were given an intramuscular (IM) or subcutaneous (SC) injection of an aqueous solution of norfloxacin nicotinate (NFN) and some were also given an IM injection of saline. Serum creatine kinase (CK) activity was measured immediately before and at intervals after treatment, and turkeys were also killed at intervals to assess the extent and duration of local tissue damage at the injection site. IM injection of saline and SC injection of NFN resulted in minimal damage. At 8 h post-treatment serum CK activity was two to three times greater than the pretreatment value, but was back to the pretreatment level by 72 h. IM injection of NFN resulted in a level of CK activity that was 9.83 ± 5.16 (mean ± standard deviation) times greater than pretreatment value, and also swelling and haemorrhage at the injection site and microscopic changes characteristic of severe irritation. Histological evidence of muscle repair was delayed for 5 days after IM NFN administration although serum CK activity has returned to pretreatment levels by this time. These results suggest that the rise in serum CK activity in the turkeys correlated well with the extent of muscle tissue damage, but poorly with its duration. INTRODUCTION Intramuscular (IM) injection of a number of drugs and of vehicles containing glycerol formal, propylene glycol, emulsifiers or preservatives may cause tissue damage at the injection site in both man and animals, and the subject has been extensively reviewed (Rasmussen, 1980] Kern, 1987; Svendsen, 1988). Tissue damage at the injection site has been described after IM injection of antibiotics, chemotherapeutics and vitamins in food producing animals, but injection of saline or sterile water caused little or no tissue reaction. Macroscopically, swelling, oedema, haemorrhage and fibrosis were the most common features observed, whereas histological examination showed changes characteristic of a foreign body reaction. Both the drug and the vehicle can cause tissue injuries. Furthermore, tissue damage may vary from one animal species to another and may depend on Received 1 March 1994; Accepted 20 June 1994.

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the drug concentration and the volume injected (Rasmussen, 1980; Ladage et al., 1980; Svendsen, 1988). Data from birds are limited relative to the amount of data available on the subject in man and animals. Macroscopic and microscopic changes at the injection site of hens were reported (Blom & Rasmussen, 1976) after IM administration of aqueous solutions of streptomycin, tetracycline, oxytetracycline and sulphàdimidine, an aqueous suspension of procaine penicillin plus streptomycin and tylosin dissolved in propylene glycol. In these studies, the extent of tissue damage was estimated at a single time after treatment, usually 6 days. The progressive outcome of muscle injury and repair, and effects on serum enzyme activity, after parenteral administeration of doxycycline to pigeons (Columba livid) have been described (Dorrestein et al, 1986). The enzyme creatine kinase (CK, EC 2.7.3.2) is found predominantly in skeletal muscle, myocardium and brain, and the activity of this enzyme in serum or plasma is frequently used to detect either skeletal or cardiac muscle damage in many species (Svendsen, 1988). Although there are published reference values for this enzyme in avian species (Bogin, 1991) data are not available on the changes in the activity of this enzyme in the serum of turkeys after parenteral administration of veterinary medicinal products. Norfloxacin nicotinate (NFN) is a new antibacterial fluoroquinolone recently introduced into veterinary medicine for the treatment of various bacterial and mycoplasmal infections in food animals and poultry. The pharmacokinetics of aqueous NFN in turkeys after systemic administration have been described (Gulkarov & Ziv, 1994). A standard test for evaluation of muscle damage after a single injection has been accepted (Gray, 1981). The test consists of a three-part study on gross characterization of the lesion, a microscopic observation of tissue changes and a determination of serum CK activity. The present report correlates macroscopic and microscopic injection site damage with serum CK activity after IM and subcutaneous (SC) injection of an aqueous solution of NFN in turkeys.

MATERIALS AND METHODS Turkeys Seventeen white Nicholas turkeys were used. They were 6-8 weeks of age at the outset and their body weights ranged from 2.5 to 3.6 kg. They were housed in wire cages, fed on antibiotic-free mash and had free access to drinking water.

Norfloxacin nicotinate QuinAbic 7% (ABIC Ltd, Netanya, Israel) containing 70 mg NFN (50 mg norfloxacin free acid)/ml was used at a dose equivalent to 10 mg/kg body weight. Injected volumes ranged from 0.55 to 0.75 ml and were administered with a 64-mm, 21-gauge disposable needle.

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Table 1. Treatment regime Treatment No. of turkeys 3 4 3 6 1

DayO IM saline" IM saline IM saline

Day 10 SC QuinAbicb SC QuinAbic IM QuinAbicb IM QuinAbic

'One bird killed 24, 48 and 72 h. •Two birds killed after 24 h and one after 72,120, 148, 216 and 264 h.

Treatment The treatment was given in two phases (Table 1). At day 0, eight turkeys were given an IM injection of 1.0 ml sterile saline solution in the left superficial pectoral muscle. Ten days later four of these turkeys and three previously untreated birds were given QuinAbic by SC injection into the upper dorsal neck region. Also at 10 days six untreated turkeys, together with one bird that has received saline at day 0, were given an IM injection of QuinAbic in the left superficial pectoral muscle.

Serum CK activity Wing vein blood samples of 2.5 to 5.0 ml were collected from all birds using a 21-gauge needle immediately before saline and drug administration, and also 4, 8, 48 and 72 h after injection. Blood samples were also collected from the remaining birds at 120, 148, 216 and 264 h after the IM administration of the drug. Blood was allowed to clot at ambient temperature for 2 to 3 h, the serum was collected after centrifugation and presented for CPK assay. This was conducted at 30°C either on the day of sample collection or on the following day using a commercially available kit (RAICHEM®, Reagents Applications, Inc., San Diego, CA 92111, USA).

Examination of injection site The turkeys were killed according to the schedule on Table 1 by severing both carotid arteries and jugular veins to facilitate maximum bleeding. The skin over the pectoral muscles was freed and the entire sternum and attached muscle were removed. The injection site was excised for macroscopic and microscopic examinations immediately after killing. Muscle specimens from the injection site were fixed in 10% buffered formal saline solution. Following embedding in paraffin wax, transverse and longitudinal 5 /im sections were cut and stained with haema-

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toxylin and eosin (HE), phosphotungstic acid haematoxylin (PTAH) and Masson's trichrome. The SC injection site was not examined histologically. RESULTS

Macroscopic findings All the NFN treated turkeys exhibited normal general demeanour and their appetite was normal. A small red mark at the point of needle insertion was the only clear finding in the two turkeys killed 48 and 72 h after intramuscular injection of saline (Phase I). Areas of necrotic muscle tissue of variable sizes surrounded by a haemorrhagic demarcating zone were found after IM injection of NFN (Phase II). In the two turkeys killed 24 h after treatment, haemorrhages were dispersed ajong the obliquely directed plane of the muscle fibre bundles over a distance of 2 to 5 cm, whereas only a slight swelling and almost no haemorrhage was seen on the muscle surface at the injection site. In the turkeys killed 72, 120 and 148 h after IM NFN administration, the surface over the injection site showed diffuse haemorrhagic discolouration. Variable amounts of straw-coloured fluid bordered by a haemorrhagic zone were seen spreading along the injection track near to the sternum. In the turkeys killed 216 and 264 h after IM NFN injection the lesions appeared similar to those seen at 72, 120 and 148 h, but the amounts of fluids were smaller and the fluid was red to purple. Only slight skin discolouration was noted at the site of SC injection of NFN, but three of these birds has slight oedema.

Microscopic findings At 24 h after IM injection of saline, changes were limited to mechanical trauma along the line of penetration by the needle. Near this line there were foci of myofibre necrosis characterized by fragmentation of the fibres into irregular hypereosinophilic amorphous clumps. At 48 h after saline injection, there was a single focus of myofibre necrosis associated with infiltration of macrophages. The overall nature of the lesion suggested a process of resolution and healing. At 72 h after saline injection the lesion was almost invisible. Figures 1 and 2 present microscopic changes at the injection site 24 h after IM injection of NFN. At 72 h the myofibre necrosis was multifocal, but infiltration of phagocytic cells, digesting and removing the damaged cells, was the most prominent feature. Multifocal heterophilic cell infiltration, mostly at perivascular location, was noted. Inflammatory cells also infiltrated necrotic blood vessel walls. Interstitial nbrinohaemorrhagic exudate was conspicious and the lumina of a few blood vessels were occluded by thrombi (Figure 3). The microscopic appearance of the injection site 120 h after IM administration of NFN was very similar to that seen at 72 h after injection, but the most striking picture at this stage was the coexistance of necrosis with regenerative changes. Typical findings included: multifocal necrotic fibre mineralization, and the près-

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Figure 1. Injection site muscle 24 h after IM NFN administration. Myofibre necrosis is characterized by fragmentation of thefibresinto irregular amorphous clumps. Phosphotungstic acid haematoxylin (PTAH); Bar = 50 fim.

ence of cells with oval and voluminous nuclei associated with scanty eosinophilic granular cytoplasm. These cells were considered to be active fibroblasts. Occasionally, short rows of vesiculated nuclei were arranged in the middle of eosinophilic, fibrillar, elongated segments of cytoplasm (Figure 4). These cells were considered to represent newly formed myoblastic tubules. The removal of necrotic fibres was almost complete by 148 h after IM NFN administration. The salient features were the presence of newly formed short myofibres with centrally located rows of giant nuclei and adjoining sheets of immature fibroblastic cells. Limited foci of fibrinous exudation were still present, but the size of the damaged area was reduced. This may be explained by cicatricial contraction. Larger areas of myofibre regeneration were noted by 216 h (9 days) after IM injection of NFN. This process was accompanied by a few foci in which there was fibre necrosis and mineralization (Figure 5), with multifocal heterophilic cell infiltration, interstitial fibrinous exudation and haemorrhage. By 264 h (11 days) after NFN was injected IM, tissue damage and regeneration were similar in nature and extent to the findings at 9 days post-treatment. In some areas, the walls of large and small calibre blood vessels were completely necrotic. The nature of the tissue damage (i.e. regeneration and necrosis) indicates that the inciting cause was still present locally and was not completely absorbed by 11 days post-treatment.

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Figure 2. Injection site muscle 24 h after IM NFN administration. A focus ofnecrotic myofibres. Only the sarcolemma remains intact while the sarcoplasm is replaced by vacuoles in which there are macrophages (arrows) clearing up the sarcoplasmic material. PTAH; Bar= 50 pirn.

Serum CK activity Pretreatment values for serum CK activity varied widely ranging from 759 to 3376 U/l with a mean and standard deviation (SD) of 1400 ± 619 U/l, respectively (M = 22 serum samples). To correct the serum CK data for these initial differences among birds, all data were converted to ratios by dividing all posttreatment values by the pretreatment value for the corresponding bird. The mean proportional increase in serum CK is presented in Figure 6. The IM injection of saline and the SC administration of NFN caused a slight, transient (up to 72 h) rise in serum CK. In contrast, the IM injection of NFN caused a considerable rise in serum CK, but levels returned to pretreatment values by 120 h (5 days). Maximum increases in serum CK were 1.91, 2.84 and 9.83 for the IM saline, SC NFN and IM NFN administration, respectively. The area under the increase in CK values vs. time curve (AUCCK) was calculated using the trapezoidal rule without extrapolation to infinity with the help of a computer program (Brown & Manno, 1978). The mean ± SD AUCCK values U/l/h, were: 102.4 ± 9.3 after IM saline, 121.7 ± 11.3 after SC NFN and 605.4 ± 59.1 after IM injection of NFN.

DISCUSSION The present study confirmed earlier findings (Dorrestein et al, 1986) that IM injection of sterile saline solution into the pectoral muscles of birds causes minimal tissue reaction and no significant rise in serum CK. We have also shown

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Figure 3. Injection site 72 h after IM NFN administration. A fibrin thrombus is within a necrotic blood vessel (arrow). Necrotic fibres are on the left of the figure. PTAH; Bar = 50 fim.

that the SC route is safe in turkeys for injecting a product which is rather irritating and which causes muscle damage after IM administration. Since equal doses of NFN injected into turkeys by the IM and SC routes produced nearly similar

Figure 4. Injection site muscle 72 h after IM NFN administration: Regenerating tnyofibres have rows of nuclei (arrow) and are surrounded by proliferating fibroblasts. PTAH; Bar = 50 \im.

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Figure 5. Injection site muscle 216 h (9 days) after IM NFN administration. Necrotic and calcified myofibres are surrounded by fibrous tissue (arrow). HE; Bar = 50 fim.

serum drug levels and bioavailability (Gulkarov & Ziv, 1994), SC injection is the route of choice for this product in the field. The degree of muscle irritation observed after IM injection of NFN was considered moderate to severe from the extent and appearance of the lesions. This classification of severity is based on the grading system for single injection injury in muscle of rabbits (Gray, 1981). A greater inflammatory response can be expected after multiple IM injections of this product. It is possible that less tissue 15r-

• • IM saline IÜSCNFN I IIM NFN

I

CO JO

•is 6 o o.

I 24

n n n

48 72 120 Time after treatment (h)

148

216

n

264

Figure 6. Effect of IM administration of saline and NFN, and SC administration of NFN, on serum CK activity. Data are expressed as the proportional increase in CK values above the pretreatment value of 1.00. Each bar represents the mean and 1 SDfrom the mean.

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reaction would result from the IM injection of the more concentrated drug product, QuinAbic 14%, which would require one-half the injectable volume, but the absorption and bioavailability could be different from those seen after administration of QuinAbic 7% (Gulkarov & Ziv, 1994). The local toxic damage induced by the IM injection of NFN was apparently caused by direct irritation with no specificity for a particular tissue component. Toxicity of the injectable drug only for myocytes, as observed with a single injection of anaesthetics (Manor and Sadeh, 1989), is characterized by complete recovery without fibrosis. This type of reaction was not observed in the present study. It is reasonable to assume that extensive disruption of connective tissue will cause permanent reaction, i.e. fibrosis, that will persist locally (Van Vleet et al, 1991). Muscle damage of extent and duration similar to that observed in the present study was reported after intramuscular injection of several oxytetracycline formulations into pigs (Nouws, 1984), calves, pigs and sheep (Nouws et al, 1990). The microscopic characteristics of the lesions observed in the present study were somewhat different from the foreign body giant cell reactions and mineralization described in rabbits and other mammals (Rasmussen, 1980; Gray, 1981; Svendsen, 1988). This is in agreement with findings in the hen (Blom & Rasmussen, 1976) and the pigeon (Dorrestein et al, 1986). The rather late appearance of histological features indicative of muscle regeneration and even fibrosis in turkeys could have been the result of the irritating nature of the injectable product or might be linked to the rate of muscle healing processes in birds. Although obvious regeneration was noted at the site of NFN injection, acute active injury was also present (i.e. a polyphasic pattern of injury resulting from continued insult applied over prolonged time) (Van Vleet et al, 1991). This may be explained by failure of the drug to be completely eliminated from the injection site, even 11 days after treatment. Alternatively, the evidence of toxic injury to blood vessels might suggest absence of suitable conditions for uncomplicated regeneration. Of special interest are the relatively high 'normal' baseline serum CK values we have found in turkeys. Ranges of normal values, in U/l, are 59 to 396 for avian species (Bogin, 1991) and 32 to 823, (mean ± SE 208 ±20) for pigeons (Dorrestein et al, 1986). It is possible that species differences can account for the pretreatment values we observed or that serum CK values are somewhat higher in fast growing, partially stressed turkeys. An interpretation of serum CK activity requires consideration of the way in which the blood sample was collected, and the method and temperature used for the assay. In the present study venous blood was collected by piercing the skin without damaging the nearby muscle tissue, haemorrhage was minimized and the blood was stored for only a short period before assay. Incorrect venepuncture procedure and prolonged storage were quoted as factors elevating serum CK activity in several animal species (Berrett & Anderson, 1983; Jones, 1985; Fayolle et al, 1992). A sharp rise in serum CK activity, to a maximum at 24 h after treatment, was

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noted after IM injection of NFN (Fig. 6). This is commonly seen whenever substantial haemorrhage or necrosis occurs in muscle (Steiness et al., 1978). The release of CK may be more quantitatively related to the muscle damaging effects of specific substances than to the nature of the lesions (Gray, 1981). A good correlation between peak serum CK and the severity of injury was reported by others (Steiness et al, 1978; Gray, 1981; Dorrestein et al., 1986; Svendsen, 1988). The present study showed, however, that the duration of elevated serum CK activity is a poor predictor, at least in turkeys, of the rate of muscle repair. Serum CK activity returned to near pretreatment levels by 120 h after IM NFN injection, whereas there was little histological evidence suggesting diminution of tissue injury at that time or even at 148 and 216 h after IM drug administration. Efflux of CK enzyme from damaged muscle may explain the common observation that serum CK returns to normal levels 3 to 4 days after injection of irritating substances to experimental animals or man, and also in human patients suffering from an acute mycardial infarct (Svendsen, 1988). REFERENCES BERRETT, S. & ANDERSON, P.H. (1983) Changes in plasma creatine kinase activity following storage as whole blood. Veterinary Record, 113, 321. BLOM, L. & RASMUSSEN, F. (1976) Tissue damage at the injection site after intramuscular injection of drugs in hens. British Poultry Science, 17, 1-4. Bogin, E. (1991) Handbook of Veterinary Clinical Chemistry. (Rochester, New York, Eastman Kodak Co.). BROWN, R.D. & MANNO, J.E. (1978) ESTRIP, a BASIC computer program for obtaining initial polyexponential parameter estimates. Journal of Pharmaceutical Sciences, 67, 1687-1691. DORRESTEIN, G.M., DE BRUINJE, J.J. & B u t t e l a a r , M.M. (1986) Bio-availability, tissue distribution, muscle injury and effects on enzyme activity after parenteral administration of doxycycline to pigeons (Columba livia). Ph.D. thesis, State University of Utrecht. FAYOLLE, P., LEFEBVRE, H. & BRAUN, J.P. (1992) Effect of incorrect venepuncture on plasma creatine-kinase activity in dog and horse. British Veterinary Journal, 148, 161-162. GRAY, J.E. (1981) Appraisal of the intramuscular irritation test in the rabbit. Fundamental and Applied Toxicology, 1, 290-292. GULKAROV, A. & Ziv, G. (1994) Some pharmacokinetic features of norfloxacin in turkeys (Abstract). Proceedings, 6th EAVPT International Congress, Edinburgh, p. 235. JONES, D.G. (1985) Stability and storage characteristics of enzymes in sheep blood. Research in Veterinary Science, 38, 307-311. KERN, O. (1987) Lokalvertraglichkeit von Arznei- und Arzneihilfsstoffen bei intramuskularer Injektion. Tierarztliche Umschau, 42, 1-34. LADAGE, C.A. VAN WALSTIJN, T H . A . & RIESSEN, H.A. (1980) Comparative macroscopic evaluation of muscle damage in rats and cattle after intramuscular administration of some commercially available injectable medicines. In: VAN MIERT, A.S.J.P.A.M., FRENS, J. & VAN DER KERK, F.W. (Eds) pp. 34-40. (Amsterdam & New York, Elsevier Scientific Publication Co.) MANOR, D . & SADEH, M. (1989) Muscle fiber necrosis induced by intramuscular injection of drugs. British Journal of Experimental Pathology, 70, 457-462. Nouws, J.F.M. (1984) Irritation, bioavailability, and residue aspects of ten oxytetracycline formulations administered intramuscularly to pigs. Veterinary Quarterly, 6, 80-84. Nouws, J.F.M., SMULDERS, A. & RAPPALINI, M. (1990) A comparative study on irritation and residue aspects of five oxytetracycline formulations administered intramuscularly to calves, pigs and sheep. Veterinary Quarterly, 12, 129-138. RASMUSSEN, F. (1980) Tissue damage at the injection site after intramuscular injection of drugs in food-producing animals. In: VAN MIERT, A.S.J.P.A.M., FRENS, J. & VAN DER KERK, F.W. (Eds) Trends in Veterinary Pharmacology and Toxicology, pp. 27-33. Elsevier Scientific Publication Co., Amsterdam & New York.

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STEINESS, E., RASMUSSEN, F., SVENDSEN, O. & NIELSEN, P. (1978) A comparative study of serum creatine

phosphokinase (CPK) activity in rabbits, pigs and humans after intramuscular injection of local damaging drugs. Acta pharmacologia et toxocologia, 42, 357-364.

SVENDSEN, O. (1988) Studies of tissue injuries caused by intramuscular injection of drugs and vehicles. Ph.D. thesis, Faculty of Medicine, University of Copenhagen. VAN VLEET, J.F., FERRANS, V.J. & HERMAN, E. (1991) Cardiovascular and skeletal muscle systems. In:

Handbook of Toxicologic Pathology, HASCHEK, W.M. & ROUSSEAUX, C.G. (Eds), pp. 539-624. (San Diego, CA, Academic Press).

RESUME Corrélation entre la réaction au point d'injection et l'activité sérique de la créatine kinase chez des dindes après injection intramusculaire et sous cutanée de nicotinate de norfloxacine Des dindes ont reçu une injection intramusculaire (IM) ou sous-cutanée (SC) d'une solution aqueuse de nicotinate de norfloxacine (NFN) et quelques-unes ont reçu également une injection en solution saline. L'activité sérique de la créatine kinase (CK) a été mesurée immédiatement avant et à intervalles réguliers après traitement; des dindes ont été également abattues à différentes intervalles pour déterminer l'étendue et la durée des réactions locales tissulaires au point d'injection. L'injection IM de solution saline et l'injection SC de NFN a entraîné le minimum de dommages. Huit heures après traitement, l'activité sérique (CK) a été de deux à trois fois supérieures à la valeur initiale, rétablie 72 heures après traitement. L'injection IM de NFN s'est traduite par un niveau d'activité CK qui était 9, 83 ± 5,16 fois plus élevé (moyenne de déviation standard) que la valeur avant traitement et également par des hémorragies et oedèmes au point d'injection avec des modifications microscopiques caractéristiques d'une sévère irritation. Histologiquement, la réparation musculaire est apparue cinq jours après l'injection IM de NFN, de même l'activité sérique CK est revenue au niveau initial dans le même temps. Ces résultats suggèrent que l'élévation de l'activité sérique CK chez les dindes est bien corrélée avec l'étendue de la réaction musculaire locale mais peu avec sa durée.

ZUSAMMENFASSUNG Korrelation von Schäden an der Injektionsstelle und Serum Kreatinkinaseaktivität bei Puten nach intramuskulärer und subkutaner Verabreichung von Norfloxacinnikotinat Puten erhielten eine intramuskuläre (i.m.) oder subcutane (s.c.) Injektion einer wässerigen Norfloxacinnikotinat (NFN)-Lösung, und einigen wurden auch Kochsalzlösung i.m. injiziert. Die Serum-Kreatininkinase (CK)-Aktivität wurde unmittelbar vor der Behandlung und periodisch danach gemessen. Außerdem wurden in gwissen Abständen Puten getötet, um Ausmaß und Dauer lokaler Gewebeschädigungen an der Injektionsstelle zu beurteilen. Die i.m. Injektion von Kochsalzlösung und s.c. Injektion von NFN ergaben minimale Schädigungen. Acht Stunden nach der Behandlung war die Serum-CK-Aktivität zwei- bis dreimal höher als vor der Behandlung, ging aber bis 72 Std. nach der Behandlung auf den Ausgangswert zurück. Die i.m. Injektion von NFN resultierte in einem CK-Spiegel, der 9,83 ±5,16 (Mittelwert ± Standardabweichung) mal höher war als vor der Behandlung, und es kam auch zu Hämorrhagie und Schwellung an der Injektionsstelle und zu mikroskopischen Veränderungen, die für eine starke Reizung charakteristisch sind. Histologische Anzeichen der Muskelwiederherstellung waren nach der i.m. NFM-Verabreichung 5 Tage lang verzögert, obwohl die CK-Konzentration im Serum zu dieser Zeit wieder auf den Ausgangswert zurückgegangen war. Diese Ergebnisse lassen darauf schließen, daß bei den Puten die Erhöhung des CK-Spiegels im

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Serum gut mit dem Ausmaß der Schädigung des Muskelgewebes, aber schlecht mit deren Dauer korreliert war.

RESUMEN Correlación de la lesión local y los niveles de actividad de la creatin kinasa en pavos tras la administración intramuscular y subcutánea de nicotinato de norfloxacina Se administró a pavos una inyección intramuscular (IM) o subcutánea (SC) de una solución acuosa de nicotinato de norfloxacina (NFN) y se compararon diversos parámetros con la administración intramuscular de solución salina en otras aves. La actividad de creatin kinasa (CK) sérica se midió inmediatamente antes y a ciertos intervalos tras el tratamiento, siendo sacrificadas las aves a intervalos para comprobar la extensión y duración de la lesión tisular local en el lugar de la inyección. La inyección IM de solución salina y la inyección SC de NFN produjo un daño mínimo. A las 8 h de la inyección, la actividad CK sérica fue dos a tres veces más grande que los valores previos al tratamiento pero retornó a los valores basales a las 72 h. La inyección IM de NFN dio como resultado una actividad CK de 9.83 ±5.16 (media ± desviación stándar) veces más elevada que los valores basales, observándose también tumefacción y hemorragias en el lugar de inyección y lesiones microscópicas características de una irritación intensa. No se observaron signos histológicos de reparación del músculo afectado hasta el quinto día tras el tratamiento aunque la actividad CK sérica había retornado a los valores basales con anterioridad. Estos resultados sugieren que el incremento de la actividad sérica de CK en los pavos tuvo una correlación buena con la extensión del daño muscular pero ésta fue pobre si se relacionó con la duración de la lesión.