The parenteral toxicity of clindamycin 2-phosphate in laboratory animals

Freund's complete and incomplete adjuvants, preparation, and quality control standards for experimental laboratory animals use

Quality control and quality assurance procedures are discussed for the agreed benchmark standard Freund's complete adjuvant (FCA). In addition, the use of the incomplete adjuvant (FIA) in the preparation of antisera is discussed. A major problem is the use of a safe and suitable mineral oil in FCA and FIA; manufacturers should provide infra-red spectra and gas liquid chromatography analyses. A range of safety tests, toxicity, pyrogenicity and endotoxin assays and advice on practical procedures for the use of these adjuvants are described.

Prodrug strategies to overcome poor water solubility

Drug design in recent years has attempted to explore new chemical spaces resulting in more complex, larger molecular weight molecules, often with limited water solubility. To deliver molecules with these properties, pharmaceutical scientists have explored many different techniques. An older but time-tested strategy is the design of bioreversible, more water-soluble derivatives of the problematic molecule, or prodrugs. This review explores the use of prodrugs to effect improved oral and parenteral delivery of poorly water-soluble problematic drugs, using both marketed as well as investigational prodrugs as examples. Prodrug interventions should be considered early in the drug discovery paradigm rather than as a technique of last resort. Their importance is supported by the increasing percentage of approved new drug entities that are, in fact, prodrugs.

Safety of archaeosome adjuvants evaluated in a mouse model

Archaeosomes, liposomes prepared from the polar ether lipids extracted from Archaea, demonstrate great potential as immunomodulating carriers of soluble antigens, promoting humoral and cell mediated immunity in the vaccinated host. The safety of unilamellar archaeosomes prepared from the total polar lipids (TPL) of Halobacterium salinarum, Methanobrevibacter smithii or Thermoplasma acidophilum was evaluated in female BALB/c mice using ovalbumin (OVA) as the model antigen. Groups of 6-8 mice were injected (0.1 mL final volume) subcutaneously at 0 and 21 days, with phosphate buffered saline (PBS), 11 microg OVA in PBS, 1.25 mg of antigen-free archaeosomes in PBS (ca 70 mg/kg body wt), or PBS containing 11-20 microg OVA encapsulated in 1.25mg archaeosomes. Animals were monitored daily for injection site reactions, body weight,temperature and clinical signs of adverse reactions. Sera were collected on days 1, 2, 22, and 39 for analyses of creatine phosphokinase. Mice were sacrificed on 39 d, sera were collected for biochemical analyses, and major organs (liver, spleen, kidneys, heart, lungs) were weighed and examined macroscopically. There were no indications of adverse reactions or toxicity associated with any of the archaeosome adjuvants. None of the antigen-free archaeosomes elicited significant anti lipid antibodies when subcutaneously injected (1 mg each at 0, 1, 2, and 4 weeks) in mice, although anti H. salinarum lipid antibodies were detected. These antilipid antibodies cross-reacted with the TPL of T. acidophilum archaeosomes but not with the TPL of M. smithii archaeosomes nor with lipids of ester liposomes made from L-alpha-dimyristoylphosphatidylcholine (DMPC), L-alpha-dimyristoylphosphatidylglycerol (DMPG), and cholesterol (CHOL). In vitro hemolysis assay on mouse erythrocytes indicated no lysis with M. smithii or T. acidophilum archaeosomes at up to 2.5 mg/mL concentration. At this concentration, H. salinarum archaeosomes and DMPC/DMPG/CHOL ester liposomes caused about 2% and 4% hemolysis, respectively. Based on this mouse model evaluation, archaeosomes are well-tolerated and appear relatively safe for potential vaccine applications.

A non-invasive and quantitative method for the study of tissue injury caused by intramuscular injection of drugs in horses

The present study was undertaken to measure the weight of muscle destroyed by an intramuscular injection of phenylbutazone (PBZ) in horses. In six horses, CK disposition parameters were evaluated after intravenous (i.v.) and intramuscular (i.m.) administration of a CK horse preparation. The same horses received PBZ, a potentially irritating agent, by i.v. and i.m. (neck and hindquarter) routes. Data were analysed using compartmental approaches and instantaneous CK flux was calculated using a discrete deconvolution method. For a 150 U/kg CK dose, the steady-state volume of distribution was 0.050 +/- 0.0115 L/kg and the plasma half-life was 112 +/- 18 min. After CK i.m. administration, the half-life of the terminal phase was 11.8 +/- 5.3 h indicating a flip-flop process and the mean bioavailability of CK was close to 100%. After PBZ i.m. administration, the CK activity was significantly increased with peak values of 508 +/- 109 U/L after the neck administration and 873 +/- 365 U/L after the gluteal administration. By measuring the total amount of CK released from injured muscle, it was calculated that an equivalent of 0.044 +/- 0.029 g/kg of muscle was destroyed after PBZ administration in the neck. The corresponding figure was 0.118 +/- 0.048 g/kg after intragluteal PBZ administration. By deconvoluting plasma CK activity, it was shown that the CK entry rate was maximum for the first 30-60 min following PBZ administration, which then decreased slowly to return to the control value after a delay of 24-48 h after PBZ administration. It was concluded that the CK release pattern following a controlled muscular damage was a non-invasive approach useful for quantifying the amount of damaged muscle, and that the calculation of CK input rate by deconvolution was of potential interest in describing events at the muscle cell level.

Formulation of vaccine adjuvant muramyldipeptides. 3. Processing optimization, characterization, and bioactivity of an emulsion vehicle

An efficacious vaccine adjuvant which elicits both cell-mediated immunity (CMI) and humoral immune response was developed using [thr1]-Muramyldipeptide (MDP) in an oil-in-water emulsion vehicle containing poloxamer 401, polysorbate 80, and squalane. Processing optimization was performed to increase the physical stability of this adjuvant emulsion which, when prepared by conventional mixing methods, demonstrated good bioactivity but poor physical stability. Various manufacturing methods were compared with a microfluidization process, which produced the most stable and elegant emulsion vehicle. The microfluidized emulsion also elicited equivalent biological response in the animal model tested.

An in vitro model to evaluate muscle damage following intramuscular injections

An isolated rat muscle preparation was developed to screen for muscle damage (myotoxic potential) following intramuscular injections. Myotoxicity is evaluated by the total cumulative efflux of the enzyme creatine kinase from the extensor digitorum longus muscle into the incubation medium over a 2-hr period or by the slope of the cumulative creatine kinase efflux curve. The system allows for rapid screening of compounds and/or formulations regarding their myotoxic potential and is not sensitive to fluctuations of in vivo creatine kinase levels caused by animal handling or patient conditions. A good rank-order correlation was obtained between this in vitro technique and the in vivo myotoxicity of a number of pharmaceutical formulations, as indicated by circulating creatine kinase levels and histological observations.

[Changes in creatine kinase activity in serum following intramuscular injection]

The effect of intramuscular injections of two multivitamin preparations, two excipient preparations without vitamins, and a placebo preparation (glycine 2.5%) on serum creatine kinase activity (S-CK) in ten healthy volunteers (three female, seven male) aged between 23 and 25 years was investigated. One of the multivitamin preparations contained no lidocaine, the other 1% lidocaine. The one excipient formulation was isoosmotic, while the other contained added saline to bring it to the same degree of hyperosomolarity as the multivitamin formulation without lidocaine. The formulations were administered by deep ventrogluteal injection by means of a standardized injection technique. Blood samples were taken before and 6, 12, 24 and 48 h after injection. Following the administration of all the formulations except that of the glycine 2.5%, a marked increase in S-CK activity (1260 I.U./l) was observed 12 h after injection (normal range: male: 47-243 I.U./l, female: 39-226 I.U./l). The relative standard deviation for the 12 h S-CK value was 66.4-97.3%. On applying a threeway analysis of variance to the parameter S-CKmax, no significant differences (alpha = 5%) were found between the effects of the multivitamin and excipient formulations. There was a difference between these and glycine 2.5%, however. There were significant differences between individual volunteers but no significant differences based on the sequence in which the injections were given. With regard to the parameter S-CK AUC (area under the curve, trapezoidal rule), a significant difference (alpha = 5%) was observed only between glycine 2.5% and the multivitamin formulation containing 1% lidocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue tolerance of intramuscular injectables and plasma enzyme activities in rats

The local tissue damage after intramuscular injection caused by various commercially available injection solutions was determined in the albino rat, by measuring plasma activities of creatine phosphokinase, aspartate aminotransferase, and lactic dehydrogenase, the tissue activity of creatine phosphokinase, and macroscopic changes in the muscle at the injection site (gastrocnemius muscle). The plasma enzyme activities were determined 2, 6, 18, and 28 hr after the injection. After 28 hr the animals were sacrificed for macroscopic inspection of the injection site and for the determination of tissue enzyme activity. The tissue injury caused by the test substances correlated well with the elevated creatine phosphokinase activity (2 hr). The elevations of aspartate aminotransferase (18 hr) and lactate dehydrogenase (2 hr) activity as well as the loss of tissue creatine phosphokinase activity were less indicative of differences between test preparations. The i.p. administration of some of the test preparations caused increased enzyme activity without muscle damage, which could interfere with the test results. The creatine phosphokinase determination indicates the damage occurring immediately after the administration of the test solution, and the macroscopic inspection offers the possibility to obtain some information on the evolution of the muscular lesion.

Adjuvant formulation for use in vaccines to elicit both cell-mediated and humoral immunity

Adjuvant formulations which elicit both humoral and cell-mediated immunity will be required for vaccines based on peptides, viral and bacterial subunits and genetically engineered antigens. This report describes an adjuvant formulation which increases both cell-mediated and humoral immunity and is free of significant side effects encountered with other adjuvants or vehicles. The components include the threonyl analogue of muramyl dipeptide, Tween 80, Pluronic L121 and squalane. This formulation was found to be effective with several antigens, in several species, including rodents, cats and monkeys. These results suggest that the formulation will be useful for both human and veterinary vaccines.

Prodrugs. Do they have advantages in clinical practice?

Prodrugs are pharmacologically inactive chemical derivatives of a drug molecule that require a transformation within the body in order to release the active drug. They are designed to overcome pharmaceutical and/or pharmacokinetically based problems associated with the parent drug molecule that would otherwise limit the clinical usefulness of the drug. The scientific rationale, based on clinical, pharmaceutical and chemical experience, for the design of various currently used prodrugs is presented in this review. The examples presented are by no means comprehensive, but are representative of the different ways in which the prodrug approach has been used to enhance the clinical efficacy of various drug molecules.

A comparative study of serum creatine phosphokinase (CPK) activity in rabbits, pigs and humans after intramuscular injection of local damaging drugs

Serum creatine phosphokinase (CPK) activity has been determined before and after intramuscular injection of lidocaine, diazepam or saline in humans and lidocaine, diazepam, digoxin and saline in pigs and rabbits. Two ml volum of each of the drugs was given to humans as well as to the experimental animals. No changes in CPK activity were found after saline in humans or rabbits but a minor increase was demonstrated in pigs. A marked increase of CPK activity was demonstrated after lidocaine or diazepam in humans and after lidocaine, diazepam or digoxin in pigs and rabbits. Post mortem examination of the injection sites in the animals revealed extensive muscle tissue necrosis after lidocaine, diazepam and digoxin. No damage of the tissue was found after saline. CPK activity was also determined in rabbits receiving 2 ml of dilutions of diazepam in saline. The injection sites were examined post mortem. The CPK activity was increased in animals receiving 1:2 and 1:8 dilutions while a 1:20 dilution did not give rise to changes in the enzyme activity. The necrotic area diminished when diazepam was diluted and no pathological changes were found at the injection sites after the 1:20 dilution. Measuring the CPK activity in rabbits after an intramuscular injection seems to be a sensitive method for the determination of local toxicity.