Paracetamol [acetaminophen]-induced gastrotoxicity: revealed by induced hyperacidity in combination with acute or chronic inflammation.

Paracetamol is regarded as a relatively safe drug in the gastro-duodenal region of humans but recent epidemiological investigations have suggested that at high doses there may be an increased risk of ulcers and bleeding. To investigate the possibility that inflammatory conditions and gastric acidity may play a role in potentiating development of gastric mucosal injury from paracetamol in rats (as noted previously with various non-steroidal anti-inflammatory drugs) we studied the gastric irritant effects of paracetamol and some phenolic and non-phenolic analgesics and antipyretics in rats with adjuvant or collagen II induced arthritis or zymosan-induced paw inflammation and given 1.0 ml hydrochloric acid (HCl) 0.1 M and/or an i. p. injection of the cholinomimetic, acetyl-beta-methyl choline chloride 5.0 mg/kg. Gastric lesions were determined 2 h after oral administration of 100 or 250 mg/kg paracetamol or at therapeutically effective doses of the phenolic or non-phenolic analgesics/antipyretics. The results showed that gastric mucosal injury occurred with all these agents when given to animals that received all treatments so indicating there is an adverse synergy of these three factors, namely: (i) intrinsic disease; (ii) hyperacidity; and (iii) vagal stimulation for rapidly promoting gastric damage, both in the fundic as well as the antral mucosa, for producing gastric damage by paracetamol, as well as the other agents. Removing one of these three predisposing factors effectively blunts/abolishes expression of this paracetamol-induced gastrotoxicity in rats. These three factors, without paracetamol, did not cause significant acute gastropathy.

Arthritic disease suppression and cartilage protection with glycosaminoglycan polypeptide complexes (Peptacans) derived from the cartilage extracellular matrix: a novel approach to therapy.

Molecular fragments of cartilage are antigenic and can stimulate an autoimmune response. Oral administration of type II collagen prevents disease onset in animal models of arthritis but the effects of other matrix components have not been reported. We evaluated glycosaminoglycan polypeptides (GAG-P) and matrix proteins (CaP) from cartilage for a) mitigating disease activity in rats with collagen-induced arthritis (CIA) and adjuvant-induced arthritis (AIA) and b) stimulating proteoglycan (PG) synthesis by chondrocytes in-vitro. CIA and AIA were established in Wistar rats using standard methods. Agents were administered orally (10-200 mg/kg), either for seven days prior to disease induction (toleragenic protocol), or continuously for 15 days after injecting the arthritigen (prophylactic protocol). Joint swelling and arthritis scores were determined on day 15. Histological sections of joint tissues were assessed post-necropsy. In chondrocyte cultures, CaP + / - interleukin-1 stimulated PG biosynthesis. CaP was also active in preventing arthritis onset at 3.3, 10 or 20 mg/kg in the rat CIA model using the toleragenic protocol. It was only active at 20 and 200 mg/kg in the CIA prophylactic protocol. GAG-P was active in the CIA toleragenic protocol at 20 mg/kg but chondroitin sulfate and glucosamine hydrochloride or glucosamine sulfate were all inactive. The efficacy of CaP in the rat AIA model was less than in the CIA model. These findings lead us to suggest that oral CaP could be used as a disease-modifying anti-arthritic drug.

Treating inflammation: some (needless) difficulties for gaining acceptance of effective natural products and traditional medicines.

The quality of so-called 'natural medicines' is extraordinarily variable. Lack of resolute pharmacological assays contributes to this hiatus. More stringent evaluation of anti-inflammatory and anti-pyretic activities in rats can help resolve some of the uncertainties surrounding (a) preparations of some herbal products including so-called 'nature's aspirin' (e.g. willowbark, ginger), cat's claw, celery seed, etc., and (b) some animal lipids (e.g. Lyprinol(R) (NZ Mussel), emu and fish oils). These animal products can be a remarkable resource for supplementing conventional/allopathic therapy for inflammatory disease, e.g. providing lipoxygenase inhibitors. Beyond the verifiable science, the healing professions and the general public still need to examine more carefully criteria for QUALITY(S) in any alternative medicine-to ensure the good (= both reputations and products) are not destroyed by the bad-in essence counteracting Gresham's Law which states: the bad tends to displace the good.

Combination anti-inflammatory therapy: synergism in rats of NSAIDs/corticosteroids with some herbal/animal products.

A useful function of any complementary medicine is to supplement some of the benefits from other treatment modalities. In rats, extracts from Indian celery seed and the NZ green-lipped mussel are powerful nutraceuticals that (i) amplify the potency of salicylates and prednisone for treating pre-established chronic inflammation (arthritis, fibrosis) and (ii) reduce the steroid's gastrotoxic and lymphopenic side effects. Such combinations might also be useful for treating inflammatory components of (a) osteoarthritis caused by microcrystalline hydroxyapatite (BCP) and (b) pseudo-gout, associated with calcium pyrophosphate crystals; that are usually refractory to monotherapy.

Lyprinol: anti-inflammatory and uterine-relaxant activities in rats, with special reference to a model for dysmenorrhoea.

Lyprinol exhibits anti-inflammatory activity distinct from that of most NSAIDs, controlling chronic but not acute inflammation. Unlike Cox-1 inhibitors (aspirin, meclofenamic acid) it is not gastro-toxic. Predosing rats with Lyprinol can modify both (i) the spontaneous and (ii) the oxytocin-induced contractions of the uterus. In humans there is anecdotal evidence that Lyprinol can relieve dysmenorrhea. This report explores the concept that the uterotrophic actions of Lyprinol are conditioned by: the intrinsic profile of estrogenic hormones and progestagens and, certain extrinsic stimuli. Evidence from in vitro studies indicates that Lyprinol is not a smooth muscle relaxant and that its uterotrophic mechanism is not that of a cyclo-oxygenase inhibitor, but may mimic that of a leukotriene receptor antagonist.

Emu oil(s): a source of non-toxic transdermal anti-inflammatory agents in aboriginal medicine.

The 'oil' obtained from emu fat can be a very effective inhibitor of chronic inflammation in rats when applied dermally (with a skin penetration enhancer). Assays for this activity using the adjuvant-induced arthritis model have shown: i. Considerable variability in potency of some commercial oil samples; ii. Little or no correlation of activity with colour or linolenic acid (18:3) content of the oil; iii. Relative stability of some active oils (to heat, ageing at room temperature); iv. The bulk of the anti-inflammatory activity was present in a low triglyceride fraction; and v. Potential arthritis-suppressant/immunoregulant activity of these active fractions. These studies point to the need for more rigid quality control before considering such a (now proven) traditional medicine as a complementary therapy.Repeated applications of selected oils did not induce any of the more prominent side-effects associated with NSAIDs (e.g. platelet inhibition, gastrotoxicity) or certain anti-arthritic drugs (proteinuria, leukopenia).

Anti-inflammatory activity of a lipid fraction (lyprinol) from the NZ green-lipped mussel.

A lipid-rich extract, preparared by supercritical fluid extraction of fresh stabilized mussel powder (Lyprinol), showed significant anti-inflammatory (AI) activity given therapeutically and prophylactically po to Wistar and Dark Agouti rats developing either (a) adjuvant-induced polyarthritis or (b) collagen(II)-induced autoallergic arthritis, with ED(50)/=25 mg/kg or various therapeutic oils (flaxseed, evening primrose, fish)>/=1800 mg/kg given orally. Lyprinol showed little or no activity in acute irritation assays (carrageenan, kaolin, histamine) indicating it is not mimicking rapid-acting NSAIDs.Incorporating Lyprinol into arthritigenic adjuvants composed of heat-killed Mycobacterium. tuberculosis suspended in olive oil or squalane, effectively prevented arthritis development at a dose of 5 mg/rat. By contrast, 'dummy adjuvants' prepared with Mycobacterium tuberculosis and flaxseed, evening primrose or fish oils were still arthritigenic in Dark Agouti rats (doses of oil=90 mg/rat).Lyprinol subfractions inhibited leukotriene-B(4) biosynthesis by stimulated human polymorphonuclear leukocytes in vitro, and prostaglandin-E(2) production by activated human macrophages in vitro. Much of this AI activity was associated with polyunsaturated fatty acids and natural antoxidants (carotenoids, etc.).In contrast to NSAIDs, Lyprinol is non-gastrotoxic in disease-stressed rats at 300 mg/kg po and does not seem to affect platelet aggregation (human, rat). These data show Lyprinol to be a reproducible, relatively stable, source of bioactive lipids with much greater potency than plant/marine oils currently used as nutritional supplements to ameliorate signs of inflammation.

Changes in plasma zinc, copper, iron, and hepatic metallothionein in adjuvant-induced arthritis treated with cyclosporin.

The early changes in hepatic metallothionein (MT) and plasma zinc (Zn), copper (Cu), and iron (Fe) were investigated during the induction of adjuvant (AJ) arthritis in rats in conjunction with cyclosporin (CsA) treatment. Plasma Zn decreased after AJ injection (60% of control values at 8 h), and this was associated with a 4.5-fold increase in hepatic MT at 8 h. Plasma Zn was lowest at 16 h (40% of control), whereas hepatic MT concentrations increased to a maximum of 20-fold at 16 h. Changes in plasma Fe paralleled those of Zn, whereas plasma Cu levels were increased. Plasma metal and hepatic MT concentrations returned toward normal from d 1-7. At d 14, when marked paw swelling was apparent, hepatic MT and plasma Cu were again increased and plasma Zn decreased. Administration of CsA decreased MT induction in rats injected with AJ and also caused a marked recovery in plasma Zn and Fe levels. These changes were small but significant even in the early stages (up to 24 h) after AJ injection and were followed by a sustained improvement in all parameters, corresponding to the nonappearance of clinical arthropathy in CsA-treated rats. TNF-alpha and IL-6 production by peritoneal macrophages isolated from AJ-injected rats was significantly decreased by CsA treatment at d 7 and 14. The inhibition of hepatic MT induction during acute and chronic inflammation by cyclosporin emphasizes the role of the immune system in altered metal homeostasis in inflammation.

Zinc monoglycerolate--a slow-release source of therapeutic zinc: solubilization by endogenous ligands.

A combination of 65Zn-tracer determinations, oxidative analyses for glycerol, and a bioassay for uncomplexed Zn2+ have shown that: (i) zinc monoglycerolate (ZMG) dissolves in aqueous salt solutions/physiological media by dissociation into zinc ions and glycerol, but the rate and extent of ZMG dissolution depend upon pH, and/or concentration and complexing efficiency of zinc-ligands; (ii) under physiological conditions certain ligands present in skin and blood (e.g. citrate, lactate, albumin, histidine, glutathione and other thiols and, to a lesser extent, amino acids) accelerate ZMG dissolution; and (iii) there is a general correlation between the conditional stability constants (pH 7.3, 25 degrees C) of zinc-ligand complexes and the ability of given ligands to (a) solubilize ZMG in vitro and (b) mask the irritancy of Zn2+ in vivo. These observations indicate a mechanism for the transformation of ZMG applied transdermally or subcutaneously, to bioactive zinc (anti-arthritic nutritional supplement, etc.).

Transdermal delivery of inorganic complexes as metal drugs or nutritional supplements.

The gastro-intestinal tract presents a significant barrier to the efficient absorption of both orally administered metal drugs and dietary essential trace minerals. Absorption can be compromised by competition between alimentary metal ions, by an excess of dietary ligands (e.g. polyphosphates), or by disease (e.g. chronic inflammation). Alternative delivery by injection can be expensive, painful, often promotes systemic toxicity and usually leads to rapid elimination through excretion (bile, urine), as a consequence of bolus dosing. By contrast, our new observations indicate that presenting trace metals or metal drugs in lipophilic forms which can penetrate the dermis, permits their slow release from the skin with more efficient (relative to incipient toxicity) systemic delivery. Examples are given from our own research of dermal application of copper(II), zinc(II), titanium(IV), platinum(II) and gold(I) complexes to treat chronic inflammatory disease. Some of these compounds are also anti-cancer agents. Physical and biological constraints to transdermal (percutaneous) drug delivery are discussed together with some chemical principles governing selection of complexes as metal drugs or dietary supplements.

Zinc monoglycerolate: a slow-release source of zinc with anti-arthritic activity in rats.

Zinc repletion by parental administration of zinc monoglycerolate (ZMG) or certain other lipophilic zinc complexes, suppressed the development of adjuvant-induced polyarthritis in rats. While ZMG was effective when given parenterally over various limited time schedules (immunosuppressant, therapeutic, singledose), it was not effective given orally. The complex showed no acute anti-inflammatory activity in the carrageenan paw oedema assay and little gastric-intestinal or other organ toxicity. When injected s.c. it caused very much less local irritation than most zinc salts. Being lubrous, ZMG could be applied as the dry powder for rubbing into the skin and by this route was found to have anti-arthritic activity. 65Zn was shown to be absorbed and excreted in the faeces (biliary excretion) after applying 65Zn-ZMG dermally to shaved dorsal skin of rats. ZMG showed consistent anti-arthritic activity in rats under conditions in which 2 gold drugs (aurothiomalate, Auranofin) exhibited variable effects, depending on the strain of rat. The role of zinc and its availability in chronic inflammation are discussed on the basis of these studies.

Prevention of adjuvant-induced cachexia in rats by cyclosporin A.

The changes in food intake and biochemistry following Freund's adjuvant (AJ)-induced inflammation in rats were investigated. Injection of AJ into rats resulted in a transient anorexia but a sustained decrease in body weight. Within 14 days, body weight decreased by 12% (P less than 0.05) and adipose tissue (retroperitoneal fat pads) decreased by more than 50%. Biochemical changes seen in association with the AJ-induced wasting included decreased plasma concentrations of triglyceride and cholesterol. Injection of cyclosporin-A (CS) (20 mg/kg) with the AJ decreased the anorexia, prevented the sustained loss of body weight and adipose tissue and reversed the effects on plasma triglyceride and cholesterol concentrations. Insulin concentrations were not significantly affected by the AJ or AJ/CS treatments. Peritoneal macrophages from AJ-treated rats produced 3-fold more tumour necrosis factor-alpha (cachectin) than control rats. This effect was not observed in rats treated with AJ plus CS. The results are consistent with CS preventing the release of cytokines which have anorectic and catabolic actions (IL-1, TNF), although there is also the possibility that CS has effects involving endocrine mechanisms.

Effect of dietary polyunsaturated fatty acid (PUFA) supplementation on adjuvant induced polyarthritis in rats.

Dietary treatment with fish oil reduced the severity of adjuvant induced polyarthritis in Dark Agouti rats but enhanced disease severity in Wistar-Hooded rats. The difference in effects of fish oil between strains was not related to differences in severity of disease induced in untreated rats. Genetically determined factors may influence the effects of fish oil supplementation on severity of inflammatory diseases.

Rat polyarthritis: induction with adjuvants constituted with mycobacteria (and oils) from the environment.

Mycobacteria inhabiting plants, soils and water can cause arthritis in rats. The list of arthritogenic mycobacteria from animal sources must also be extended. The arthritogenic activity is present in dead bacteria and resists extraction into ethanol-ether (1:1 v/v). Polyarthritis is only induced in conjunction with certain (oily) lipids = coarthritogens: some of these lipids are present in/on skin, intestines, etc. Isostearic acid is also a coarthritogen. Preliminary observations suggest the leprosy bacillus (M. leprae) is not arthritogenic but may confer immunity to the M. tuberculosis arthritogen. Some adjuvant-active corynebacteria/propionibacteria did not cause polyarthritis in 2 rat strains (DA, PVG) responding vigorously to mycobacterial arthritogens.

Lipophilic copper(II) formulations: some correlations between their composition and anti-inflammatory/anti-arthritic activity when applied to the skin of rats.

Copper complexes of phenols related to salicylic acid were prepared in DMSO and applied to the shaved dorsal skin of rats. The following activities were assayed: (i) suppression of the carrageenan or hydroxylapatite paw oedemas; (ii) reduction of chronic inflammation in established adjuvant arthritis; (iii) local skin toxicity. Cu(II) was an essential component. Some limited structure-activity correlations were made among alternative cupriphores. DMSO solutions of copper complexes were more potent than their solutions in ethanol. Glycerol was a beneficial additive. Reducing the acidity of some copper salicylate formulations also reduced their potency. Niflumic acid and phenylbutazone were effective non-salicylate transcutaneous cupriphores.

Inflammation in relation to dietary intake of zinc and copper.

The role of the trace metal copper (Cu) and the role of the trace metal zinc (Zn) in inflammation were studied in rats fed diets containing varying amounts of these metals. Rats fed a diet low in Cu for two months developed more carrageenin induced inflammation than did control rats eating normal food. In rats eating the low Cu diet supplemented by added Cu, inflammation was reduced to normal levels. Rats fed a diet low in Zn for three months developed more footpad swelling after challenge with carrageenin and with monosodium urate crystals than did control rats eating a normal diet.

Anti-inflammatory/anti-pyretic salicylic acid esters with low gastric ulcerogenic activity.

The methyl and some other esters of acetylsalicylic and salicylic acids and their derivatives were found to have much lower gastric ulcerogenic activity (when assayed in the stress-sensitized rat) compared with their corresponding acids. There was little or no loss in therapeutic potencies of these salicylate esters as determined by assessment of anti-inflammatory activity (against the carrageenan-induced oedema) and antipyretic activity (against yeast-induced fever in rats. The methyl ester of acetylsalicylic acid (=AME) was almost devoid of gastric irritancy/ulcerogenicity (as observed with acetylsalicylic acid) when given orally to pigs for 10 days. AME had appreciable anti-inflammatory activity in the adjuvant-arthritis model and at high doses (200 mg/kg t.i.d.) was without the lethal effects seen with acetylsalicylic acid. Moreover, no toxic effects were seen after long-term administration of 100-1000 mg/kg/day AME for 3-4 months. The results provide further evidence for the hypothesis that the carboxylic acid moiety of salicylates is a major factor in the gastric ulcerogenic activity of these drugs. The methyl esters of these salicylates may be considered as models for the development of pro-drugs and in some cases may be therapeutic alternatives to acetylsalicylic acid or salicylate.

Anti-inflammatory activity of a dermally applied copper salicylate preparation (Alcusal).

In rats, dermal (dorsum) application of an ethanolic copper salicylate complex (ECS) in ethanol with glycerol (Alcusal) effectively suppressed established polyarthritis, carrageenan-induced paw oedema and the inflammatory response to hydroxylapatite microcrystals. These responses appear to be due to some degree of synergism between the copper(II) and salicylate, i.e. not solely due to either species alone. Evidence for transdermal absorption of 64Cu from 64Cu-ECS is provided. Some safety aspects of this novel drug are discussed.