The haemodynamic profile of cromakalim in the cat

The haemodynamic profile of the novel antihypertensive agent, cromakalim (BRL 34915), has been studied in conscious and anaesthetised cats. Given orally (0.03 and 0.06 mg/kg) to conscious cats and by intravenous infusion (0.002 mg/kg/min for 7-10 min) to anaesthetised animals, cromakalim reduced arterial pressure (AP; systolic/diastolic) and total peripheral resistance (TPR) while increasing cardiac output (CO) via both its components [heart rate (HR) and stroke volume (SV)]. In both models, HR changes were minimal for reductions of AP approaching 20 mm Hg. In a second group of conscious cats, cromakalim increased mean renal blood flow (MRBF) at hypotensive doses (0.03 and 0.06 mg/kg orally); HR was only significantly raised following the higher dose of cromakalim. In anaesthetised animals, intravenously infused cromakalim had little effect on central venous pressure and increased cardiac contractility. The data indicate that cromakalim lowers AP by reducing TPR with minimal increase in HR. In addition, cromakalim has a potentially beneficial effect on MRBF.

[Analgesic effect of topically applied pranoprofen-gel]

The analgesic effect of topically applied pranoprofen-gel (1% and 3%) was investigated in comparison with indomethacin-gel in experimental animals. Applied topically, 1% and 3% pranoprofen-gel inhibited the inflammatory pain induced by Randall and Selitto's method and the pain response (abnormal gait) of concanavalin A-induced arthritis in rats dose-dependently. Furthermore, in antigen (methylated bovine serum albumin)-induced arthritis in rats, pranoprofen-gel had a concentration and application-dependent therapeutic effect on knee joint swelling and the pain response. Pranoprofen-gel had a stronger analgesic effect than indomethacin-gel in these experimental models. Both drugs inhibited the flexor reflexes of the hind limb induced by injecting bradykinin (BK) in combination with arachidonic acid into the common iliac artery of the spinal rat, but failed to do so with BK combined with prostaglandin E2 (PGE2). Moreover, pranoprofen-gel inhibited the BK-induced increase in the firing rate of the saphenous nerve of the spinal cat. These results show that pranoprofen-gel, applied topically, permeates well from the skin to the nociceptor site, relieving the hyperalgesia caused by PGs-induced sensitization of pain receptors by inhibiting their production. As a topical anti-inflammatory and analgesic agent, pranoprofen-gel is at least as effective as indomethacin-gel, so that it should have good clinical potential.

[Anti-inflammatory effect of topically applied pranoprofen-gel]

The anti-inflammatory activity and mode of action of topically applied pranoprofen-gel were investigated in comparison with indomethacin-gel in experimental animals. Applied topically, 0.3 approximately 3% pranoprofen-gel inhibited carrageenin-induced paw edema, fracture-induced paw edema, carrageenin-induced increase in vascular permeability and adjuvant arthritis in rats and ultraviolet ray-induced erythema in guinea pigs dose-dependently, with a potency slightly greater than that of indomethacin-gel. In addition, pranoprofen-gel inhibited dose-dependently the formation of granuloma caused by a cotton pellet implantation, without affecting the weight of the thymus or adrenals and without inducing gastrointestinal lesions. Moreover, applied topically to carrageenin-treated rats, pranoprofen-gel inhibited dose-dependently, and more potently than indomethacin-gel, the production of a prostaglandin E2 (PGE2)-like substance in both the exudate of the carrageenin air pouch and the inflamed synovial membrane. Both drugs inhibited the potentiation of bradykinin-induced vascular permeability in rabbit skin by arachidonic acid, but not by PGE2. Pranoprofen was only one third as potent as indomethacin in inhibiting the production of PGE2 from the phagocytosing of killed bacteria by rat peritoneal leucocytes in vitro. These results show that pranoprofen-gel, applied topically, permeates well from the skin to the deep inflammatory site, relieving potently and long lastingly the inflammation by inhibiting PG production. As a topical anti-inflammatory agent, pranoprofen-gel is at least as effective as indomethacin-gel, so it may have good clinical use.

Plasma levels, elimination and metabolic fate of 4a-amino-8-chloro-2-methyl-1,2,3,4,4a,10a-hexahydro-10H-benzopyrano[3,2-c]pyridin-10-ylacetic acid lactam, a new antidepressive agent, in rats and dogs

After single intravenous administration to dogs, 4a-amino-8-chloro-2-methyl-1,2,3,4,4a,10a-hexahydro-10H-benzopyrano[3,2-c]pyridin-10-ylacetic acid lactam (LM 1404) was rapidly distributed. Elimination from plasma was biphasic and dose-independent between 1 and 10 mg/kg, with a half-life for the beta-phase of 4.5 hr. After oral administration, LM 1404 was quickly and nearly completely absorbed. In rats, LM 1404 was rapidly absorbed and eliminated from plasma with a terminal half-life of 2.5 hr. The N-demethylated metabolite (LM 1580), which has a pharmacological activity nearly identical to that of LM 1404, was very abundant in plasma of both species, with half-lives of 13 hr in dogs and 3.5 hr in rats and areas under the curves respectively 2 and 4 times that of LM 1404. Urinary excretion was extensive; unchanged drug amounted to 7 and 1.5% and LM 1580 to 70% in dogs and rats.

Antitumor activity of newly isolated antibiotics, 3-dichloromethylactinobolins

Three new antibiotics isolated from broth cultures of a Pseudomonas were evaluated for antitumor activity against murine leukemias L1210 and P388. The antibiotic with the dichloromethyl group at the 3 position of actinobolin, an antibiotic produced by a Streptomyces, is the major product (Y-12278), and two analogs of Y-12278 are minor. When these antibiotics were administered i.p. on days 1 to 4 to mice bearing ascitic leukemias, the most effective was Y-12278, which increased the lifespan of mice implanted with leukemias L1210 and P388 by 88 and 110% over controls, respectively. On the same treatment schedule, less than 60% ILS (increase in lifespan) was obtained by oral and s.c. administration of Y-12278 to mice implanted i.p. with these leukemias, and by its i.p. injection to mice implanted i.c., i.v. and s.c. with leukemia L1210. With i.p. administration of Y-12278, a single injection on day 1 only was less effective in increasing the lifespan of mice bearing ascitic leukemias L1210 and P388 than the prolonged treatment schedules such as daily on days 1 to 4. Y-12278 administered i.p. on days 3 to 6 was shown to possess antitumor activity against i.p. implanted rat hepatomas. More than 200% ILS was seen in hepatomas AH44 and AH7974F.

Anti-allergy properties of PRD-92 Ea in guinea pig and rat

The effects of PRD-92 Ea were examined on the increased plasma protein extravasation in the skin of guinea pig and rat elicited by specific antigens and spasmogenic mediators. PRD-92 Ea was found to be a potent inhibitor of rat PCA reactions when administered intradermally, intravenously or orally. This compound did not antagonize the local inflammatory responses of histamine, bradykinin or 5HT. This implies that in vivo PRD-92 Ea acts predominantly as an anti-allergy agent rather than a spasmogen antagonist. At high concentrations PRD-92 Ea directly increased vascular permeability when injected intradermally (greater than 250 micrograms/site) or administered by aerosol into the lung (greater than 10%). The importance of investigating such direct irritant actions of similar new drugs is discussed.

The difference in effect of predosing with antiallergic compounds between the rat PCA model and the monkey asthma model. Comparison of the effects of PRD-92-Ea and disodium cromoglycate

DSCG and PRD-92-Ea showed tachyphylaxis in the rat PCA test when a large intravenous dose (40 mg/kg of DSCG and 20 mg/kg of PRD-92-Ea) was given 30 min before administering intravenously the expected effective doses at the time of antigen challenge. This predosing led to a marked loss of effectiveness. Cross-reacting tachyphylaxis was also demonstrated in this model. Predosing rats with DSCG led to a great loss of effectiveness of a subsequent expected active dose of PRD-92-Ea and predosing with PRD-92-Ea had the same effect in preventing the antiallergic action of a subsequent dose of DSCG. The Rhesus monkey (Macaca mulatta) did not exhibit this phenomenon of tachyphylaxis. PRD-92-Ea and DSCG were given intravenously 30 min before and the same dose of 20 mg/kg repeated just before Ascaris suum challenge in the Rhesus monkey asthma model with no loss of their expected effectiveness.

Interactions in man of delta-9-tetrahydrocannabinol. II. Cannabinol and cannabidiol

Oral doses of delta-9-tetrahydrocannabinol (THC) 20 mg, combined with placebo or with 40 mg dses of cannabinol (CBN) and cannabidiol (CBD), were given to volunteers. The combination of THC with CBN produced no detectable changes in the quality, intensity, or duration of the effects of THC alone. The THC-CBD combination tended to delay onset and prolong effects of THC, while making them somewhat more intense. Even this interactive effect was slight, providing no reason to abandon the current practice of basing doses of marihuana for clinical studies solely on THC content.

Experimental study of a potential anti-asthmatic agent: SCH 15280

A forced oscillations technique for measuring total respiratory system resistance was used to quantitate the bronchomotor activity of Sch 15280: (5[4-(N-methyl)-piperidylidine]5H-[1]-benzopyrano[2,3,b]-pyridine maleate) and to compare its potency to that of standard bronchodilator agents. By the intravenous route, Sch 15280 was 48 times more potent than aminophylline and 1/78 as potent as atropine in inhibiting methacholine-induced bronchoconstriction in rabbits. In cats Sch 15280 was 1/12 as potent as ephedrine in inhibiting histamine-induced bronchoconstriction and had a greater protective activity against histamine-induced bronchoconstriction and had a longer duration of action than 0.5% solution of isoproterenol. Statistical tests of parallelism revealed a significant difference between the log dose-response curves of Sch 15280 and ephedrine but not between those of Sch 15280, atropine and aminophylline. The results suggest that Sch 15280 can act via, a nonadrenergic mechanism to block both histaminergically and cholinergically mediated responses in the tracheobronchial tree. This pharmacologie profile may have important therapeutic application in the type I immediate hypersensitivity reactions of man.