Risk factors and predictors of treatment responses and complications in immune thrombocytopenia.

Management of adult patients with immune thrombocytopenia (ITP) is often unsatisfactory, due to variable efficacy of treatment, risk of life-threatening bleeding if disease control is poor, and side effects associated with treatment. Lack of data on the platelet count threshold associated with bleeding and infection risk associated with ITP treatment limits risk/benefit clinical decision making. We reviewed medical records of all ITP patients who were admitted to our hospital between 2012 and 2017 to evaluate the platelet count threshold for bleeding, infection burden associated with treatment, and real-world efficacy of second-line treatment. We demonstrated fair discrimination between platelet count and occurrence of bleeding, with 15 × 109/L being the optimal cut-off for predicting any bleeding while 20 × 109/L had the highest negative predictive value for severe bleeding. In multivariable analyses, patients who were treated with corticosteroids for at least 2 months were 5.3 times as likely to have an infection. In addition, rituximab response was strongly associated with response to frontline corticosteroids and infection was associated with older age ≥ 65 years and corticosteroid dependence. If corticosteroids are initiated, physicians should aim for the shortest duration of treatment before switching to effective second-line agents for hemostatic platelet counts.

Pharmacological modulation of gut mucosal and large vessel blood flow.

BACKGROUND: Constipation, diminished gut blood flow, ischaemic colitis and drug therapy may be associated. AIM: To study the effect of constipating medication on, and the regulation of, gut blood flow. METHODS: 24 healthy females (mean age 30) received, in a double-blind, three-way crossover study: (i) placebo, (ii) ipratropium 40 microg by inhalation (positive control known to reduce rectal mucosal blood flow) and (iii) oral loperamide 4 mg. Mucosal blood flow was measured at the splenic flexure and rectum using laser Doppler flowmetry. Blood flow in the superior and inferior mesenteric arteries was measured by trans-abdominal Doppler ultrasound. RESULTS: Ipratropium decreased rectal mucosal blood flow by 16% (P=0.009) and splenic flexure mucosal blood flow by 8% (P=0.075). Loperamide caused no change in rectal (P=0.40) or splenic flexure mucosal blood flow (P=0.73). Neither treatment changed superior or inferior mesenteric artery blood flow. Splenic flexure mucosal blood flow showed a positive correlation with rectal mucosal blood flow (r=0.69; P<0.0001). CONCLUSIONS: Vasoactive agents may reduce gut mucosal blood flow in the absence of reduced large vessel flow. Constipating drugs do not necessarily reduce gut blood flow. Rectal mucosal blood flow correlates with splenic flexure mucosal flow, and potentially may be used as a more convenient surrogate for studying splenic flexure blood flow.

Efficacy and safety of bisacodyl in the acute treatment of constipation: a double-blind, randomized, placebo-controlled study.

BACKGROUND: Although laxatives are a first-line treatment for constipation, there are few randomized placebo-controlled trials assessing their efficacy. AIM: To determine the effect and safety of oral bisacodyl on stool frequency and consistency in patients with idiopathic constipation. METHODS: 55 patients (age 19-89 years) with idiopathic constipation were recruited from eight primary care practices and randomized to receive bisacodyl, 10 mg once daily, or placebo, on three successive days following a 3-day run-in period. Patients recorded stool frequency and consistency and adverse events. RESULTS; In each treatment group, 27 patients were evaluable for efficacy. The mean number of stools per day was significantly greater in the bisacodyl-treated group (1.8/day) compared with placebo (0.95/day) over the treatment phase (P=0.0061). Mean stool consistency score improved from 'hard' (run-in) to between 'soft' and 'well-formed' during bisacodyl treatment, remaining between 'moderately hard' and 'hard' for placebo treatment (P<0.0001). The investigator's global efficacy score was superior for the bisacodyl group compared with placebo. Both treatments were well tolerated. Serum electrolyte levels and incidence of adverse events were comparable between treatment groups. CONCLUSIONS: Bisacodyl is effective and safe in improving stool frequency and consistency in acute treatment of idiopathic constipation.

The action of the NK1 tachykinin receptor antagonist, CP 99,994, in antagonizing the acute and delayed emesis induced by cisplatin in the ferret.

1. The anti-emetic effects of the NK1 tachykinin receptor antagonist, CP 99,994 (10 mg kg-1) were investigated in the ferret using a cisplatin-induced acute (day 1) and delayed (day 2 and 3) retching and vomiting model. 2. With a single cisplatin (10 mg kg-1) emetogenic challenge, the i.p. administration of CP 99,994 given as a single injection immediately following the first emetic episode, promptly abolished the retching and vomiting for a 4 h period. CP 99,994 was as efficacious as ondansetron (1.0 mg kg-1). The general toxicity of cisplatin 10 mg kg-1 precluded its use in studies of delayed emesis. 3. With a single cisplatin (5 mg kg-1) emetogenic challenge, the single administration of either CP 99,994 (10 mg kg-1) or ondansetron (1.0 mg kg-1) immediately following the first emetic episode markedly reduced or abolished the retching and vomiting for 4 h. Such single treatments failed to modify significantly the intensity of delayed emesis appearing on the second and third day. 4. With a cisplatin (5 mg kg-1) emetogenic challenge, administration of CP 99,994 (10 mg kg-1) at 8 hourly intervals, the first injection being administered 30 s post cisplatin, was associated with 4 or more abolitions of emesis during both the acute and delayed phase. A 4 hourly administration of CP 99,994 for 20 h during delayed emesis completely abolished the retching and vomiting. 5. It is concluded that cisplatin 5 mg kg-1 provides an emetogenic challenge causing an acute and delayed phase of retching and vomiting and that CP 99,994 can abolish both phases. The results may be relevant to the understanding and treatment of chemotherapy-induced emesis in man.

Towards understanding the aetiology and pathophysiology of the emetic reflex: novel approaches to antiemetic drugs.

The introduction of 5-HT3 antagonists, such as ondansetron, as antiemetic agents has transformed the management of patients receiving chemotherapy or radiation therapy. Studies in animal models with NK1 antagonists suggest that these represent a new class of antiemetic agents having a broader spectrum of activity than 5-HT3 antagonists. Compounds of this class may prove to be more effective in man against delayed emesis induced by cisplatin, post-operative nausea and vomiting and motion sickness. Thus, they have the potential to complement 5-HT3 antagonists and so provide a further advance in the management of nausea and vomiting.

The broad-spectrum anti-emetic activity of the novel non-peptide tachykinin NK1 receptor antagonist GR203040.

1. Following our earlier observations that the tachykinin NK1 receptor antagonist CP-99,994 is an effective anti-emetic in ferrets, we have examined the anti-emetic effects of a more potent and novel NK1 receptor antagonist, GR203040, against various emetic stimuli in the ferret, dog and house musk shrew (Suncus murinus). 2. In ferrets, GR203040 (0.1 mg kg-1 s.c. or i.v.) is effective against emesis induced by radiation, cisplatin, cyclophosphamide, copper sulphate, ipecacuanha or morphine. 3. In animals in which emesis had been established with cisplatin, GR203040 (1 mg kg-1 s.c.) was fully effective as an interventional treatment. No further emesis was seen in animals treated with GR203040 whilst saline-treated animals continued to vomit. 4. GR203040 (0.1 mg kg-1 s.c.) retains anti-emetic efficacy in the ferret, even when given as a 6 h pretreatment, indicating that this compound has a long duration of action. The compound is also effective orally at the same dose, when given as a 90 min pretreatment. 5. GR203040 (0.1 mg kg-1 i.v.) is fully effective against ipecacuanha-induced emesis in the dog. 6. GR203040 is effective against motion- and cisplatin-induced emesis in Suncus murinus. These effects were seen at doses an order of magnitude greater than those shown to be effective against cisplatin in the ferret. 7. In conclusion, GR203040 is a novel anti-emetic agent, and the broad spectrum of anti-emetic activity, together with activity observed in three species, suggests that this compound is worthy of clinical investigation.

Role of pepsin in the development of indomethacin-induced antral ulceration in the rat.

AIMS: To examine the effects of a pepsin inhibitor, pepstatin-A, a long acting H2-receptor blocker, loxtidine, exogenous pepsin and exogenous acid against indomethacin-induced antral ulceration in the rat. RESULTS: Indomethacin (60 mg/kg s.c.) caused antral ulceration in fasted/re-fed rats over a period of 4 h. Ulceration was prevented in a dose-dependent manner by treatment with pepstatin-A (0.1-1 mg.kg hourly) or loxtidine (3 mg/kg) given orally. Acidified methylcellulose (1 mL hourly per os) enhanced damage and also prevented protection by loxtidine (3 mg/kg per os). The protection by pepstatin-A was not altered by treatment with acidified methylcellulose but was reversed by treatment with a 10-fold excess of pepsin. CONCLUSION: These studies suggest that mucosal degradation by pepsin, rather than direct damage by luminal acid, was the major factor in the development of indomethacin-induced antral ulceration in the rat.

Profiles of emetic action of cisplatin in the ferret: a potential model of acute and delayed emesis.

The emetic profile of action of cisplatin 5 and 10 mg/kg i.p. was investigated in the ferret over a 72 and 40 h period respectively. Cisplatin 10 mg/kg induced retching and vomiting which rapidly declined after the first 8 h. Cisplatin 5 mg/kg induced a less intense emetic response which declined after 16 h but reappeared at approximately 32 h to reveal a 'delayed' retching and vomiting response. The use of cisplatin 5 mg/kg may offer a regimen to model cytotoxic acute and delayed emesis.

Synthesis of a potent antagonist of substance P by replacing the CH2SCH3 and the alpha-carboxamide groups of the methionine at [Orn6]-SP6-11 by benzyl ester groups.

Analogues of [Orn6]-SP6-11 have been synthesized in which the CH2SCH3 group of Met11 is replaced by a COOCH3 or a COOBzl group. These analogues, which were tested for agonist and antagonist activity in three in vitro preparations representative of NK-1, NK-2 and NK-3 receptor types, were full agonists at NK-1 receptors, showed very weak agonist activity at NK-2, receptors and were weak antagonists at NK-3 receptors. The above analogues were modified by substituting the alpha-carboxamide of residue 11 by a COOCH3 and a COOBzl group, respectively. The resulting analogues were found to be devoid of agonist activity in each of the functional assays. However, they showed weak antagonist activity at each receptor subtype, with the exception of the dibenzyl analogue, which was a potent and selective NK-1 receptor antagonist. It is concluded that appropriate modification of the side chain of Met11 and its alpha-carboxamide leads to a potent and selective at NK-1 receptor antagonist.

Synthesis of potent antagonists of substance P by modifying the methionyl and glutaminyl residues of its C-terminal hexapeptide and without using D-amino acids.

Analogues of [Orn6]-SP6-11 have been synthesized in which the Met11-NH2 residue is replaced by the alpha, gamma-dimethyl, alpha, gamma-dibenzyl and alpha, gamma-di-tert-butyl esters of glutamic acid. These analogues were tested in three in vitro preparations representative of NK-1, NK-2 and NK-3 receptor types for agonist and antagonist activity. The dimethyl analogue is a selective full agonist in the NK-1 receptor type and a weak antagonist in the other two receptor types, while the dibenzyl and the di-tert-butyl analogues are potent antagonists in the NK-1 receptor type and weak antagonists in the other two receptor types. It is concluded that appropriate modification at the alpha-carboxamide and the side chain of the methionine residue of substance P may induce antagonism without using D-amino acids.

Early histological features of small intestinal injury induced by indomethacin.

The early histological features of indomethacin-induced jejunal injury in the rat are described in tissues preserved by perfusion-fixation with 10% formol-saline. After an oral dose of indomethacin (15 mg/kg, known to cause severe multifocal ulceration of the rat jejunum), groups of rats were anaesthetized with subsequent perfusion-fixation of the gastrointestinal tract at 1, 2, 3, 6 and 48 h after dosing. Using routine light microscopic techniques, we have observed a sequence of four distinct stages, in time, of small intestinal injury. The earliest histological features were shortening of the villi, epithelial stratification, basal lamina degeneration, eosinophil degranulation and infiltration of the epithelium prior to infiltration of the mucosa by neutrophils. We consider that these earliest changes, seen at 1, 2 and 3 h, represent a distinct histological entity termed Type 1 change or villous 'tufting'. Type 2 change includes all of the features of Type 1 change plus the subsequent infiltration of the mucosa by neutrophils at 2, 3 and 6 h. Type 3 change includes necrosis of the upper-third of the villi and was mainly seen at 3 and 6 h. Type 4 change describes extreme injury to more than one-third of the mucosa with severe, acute inflammation and perforation of the bowel wall by 48 h. Although a small number of neutrophils had appeared to infiltrate the mucosa as early as 2 h after dosing, they were only significantly increased at 3, 6 and 48 h. Possible pathogenic mechanisms involved in shortening of villi as a result of smooth muscle contraction and the role of mucosal eosinophils in NSAID-induced jejunal injury in the rat are discussed.

Conformationally constrained tachykinin analogues: potent and highly selective neurokinin NK-2 receptor agonists.

The design and synthesis of potent and selective neurokinin NK-2 receptor agonists 12 (GR64349) and 31 are described, together with structure-activity relationships for related analogues. Compound 12 (EC50 = 3.7 nM at NK-2 receptors in the rat colon; selectivity > 1000- and > 300-fold with respect to NK-1 and NK-3 receptors, respectively) was derived by incorporation of a Gly-Leu gamma-lactam conformational constraint into the C-terminal region of the neurokinin A octapeptide analogue [Lys3]-NKA(3-10). Compound 31 (EC50 = 15 nM in rat colon) contains a novel fused-bicyclic constraint at the corresponding site in the substance P hexapeptide analogue [Ava6]-SP(6-11).

Highly potent and selective heptapeptide antagonists of the neurokinin NK-2 receptor.

Incorporation of D-Pro9 into substance P related peptides is known to enhance neurokinin NK-2 receptor agonist potency and selectivity with respect to other neurokinin receptors. We now report that replacement of D-Trp9 by D-Pro9 in the nonselective neurokinin antagonist [Arg5,D-Trp7,9, Nle11]-SP(5-11) gave a partial agonist with NK-2 receptor selectivity. Further incorporation of Pro10 provided the weak but selective NK-2 antagonist Arg-Ala-D-Trp-Phe-D-Pro-Pro-Nle-NH2 (compound 4; NK-2 pKB = 5.9; NK-1 pKB = 4.7; NK-3 pKB less than 4.6). Addition of a suitable lipophilic N-terminal substituent (e.g. Boc, PhCO, cyclohexylcarbonyl) to this compound greatly enhanced NK-2 antagonist activity (compound 10, GR 83074; NK-2 pKB = 8.2), and combined with further optimization of the N-terminal amino acids, provided the extremely potent and selective NK-2 antagonist PhCO-Ala-Ala-D-Trp-Phe-D-Pro-Pro-Nle-NH2 (compound 34, GR 94800; NK-2 pKB = 9.6; NK-1 pKB = 6.4; NK-3 pKB = 6.0). Compounds of this class produced a potent inhibition of NK-2 agonist-induced bronchoconstriction in the anaesthetized guinea-pig.

Characterization of tachykinin-induced ventral root depolarization in the neonatal rat isolated spinal cord.

Depolarization responses to tachykinin receptor agonists were recorded extracellularly from lumbar ventral roots of spinal cord isolated from neonatal rats (one to eight days post partum). All spinal cords were hemisected in the sagittal plane. In addition, in some hemisected cords, the dorsal horns were removed by means of a further cut, perpendicular to the first. In both hemisected and quadrisected spinal cords, reproducible depolarization responses were induced by low concentrations of the neurokinin-1-selective agonist substance P methylester (10 nM-1 microM) or of the neurokinin-3-selective agonist senktide (3-300 nM). On both types of preparation, responses to substance P methylester (1 microM) or senktide (300 nM) were of comparable size. The amplitude of the response to senktide (300 nM) was reduced by at least 88% in spinal cord preparations exposed to tetrodotoxin (0.5 microM) or to physiological medium containing magnesium chloride (20 mM). In contrast, under either of these conditions, concentration-response curves to substance P methylester were shifted rightward by 2.8-8.5-fold, with little effect on the maximum response. Responses to senktide were blocked selectively by the N-methyl-D-aspartate antagonist 3-[(+-)-2-carboxypiperazine-4-yl]propyl-1-phosphonic acid (100 microM); the antagonist had little effect on substance P methylester-induced depolarization (mean concentration ratio 2.0). These results suggest that in the neonatal rat spinal cord, application of exogenous tachykinin agonists can induce ventral root depolarization by activation of neurokinin-1 and/or neurokinin-3 receptors. The response to stimulation of neurokinin-1 receptors has a major component likely to be due to a direct action at motoneurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis of a potent agonist of substance P by modifying the methionyl and glutaminyl residues of the C-terminal hexapeptide of substance P. Structure-activity relationships.

Analogues of [Orn6]-SP6-11 have been synthesized in which the Met11 residue is replaced by glutamate gamma-alkylesters. These analogues were tested in three in vitro preparations representative of NK-1, NK-2, and NK-3 receptor types. Substitution of the SCH3 group of the Met11 side chain by a COOR (R = methyl, ethyl, n-propyl, n-butyl, cyclohexyl) group results in analogues which are full agonists in NK-1 and NK-2 preparations but show little agonist activity in the NK-3 preparation. When the SCH3 group is replaced by a t-butyl ester group and the resulting analogue is a full agonist in all the above preparations and more active than the parent hexapeptide and SP-OCH3 at NK-1 receptors. It is concluded that for activity at NK-1 receptors methionine can be replaced by gamma-t-butyl glutamate without loss of activity, whilst at NK-2 and NK-3 receptors the above substitution increases the activity of [Orn6]-SP6-11. Other gamma-alkyl esters of the glutamic acid reduce its biological activity.

Receptors mediating tachykinin-induced contractile responses in guinea-pig trachea.

1. The classification of tachykinin receptors in the guinea-pig trachea has been investigated. This was of interest because, from previous studies, it was not clear whether the guinea-pig trachea contains either a mixture of NK1 and NK2 receptors or, alternatively, a single type of novel tachykinin receptor. 2. In the present study, the guinea-pig trachea was contracted by tachykinin agonists selective for NK1 receptors (substance P methylester (SPOMe) and GR73632) or NK2 receptors (GR64349) but not NK3 receptors (senktide). 3. Against SPOMe and GR73632, the NK1 antagonist, GR71251, behaved as a reversible competitive antagonist having apparent affinity (pKB 7.05 vs SPOMe) consistent with action at NK1 receptors. GR71251 (3 microM) did not antagonize responses to GR64349. 4. The NK2 antagonists L-659,877 and Ac-Leu-Asp-Gln-Trp-Phe-Gly-NH2 (R396) antagonized GR64349 although only R396 appeared to behave competitively (pKB 5.73). Neither L-659,877 (30 microM) nor R396 (30 microM) blocked responses to SPOMe. 5. For L-659,877 and R396, comparison was made between activity in guinea-pig trachea and in preparations known to contain tachykinin receptors predominantly of the NK2 type. In the rabbit trachea, both L-659,877 and R396 had effects similar to those in guinea-pig trachea. In contrast, in the rat colon muscularis mucosae, both L-659,877 and R396 appeared to behave competitively with pKB values against GR64349 of 7.83 and 6.90 respectively. 6. It is concluded that in guinea-pig trachea, contractile responses can be induced by activation of both NK1 and NK2 receptors. The present data are discussed with reference to the proposed existence of subtypes of the NK2 receptor.

Receptor-selective, peptidase-resistant agonists at neurokinin NK-1 and NK-2 receptors: new tools for investigating neurokinin function.

The pharmacological profiles of two novel neurokinin agonists have been investigated. delta Ava[L-Pro9,N-MeLeu10]SP(7-11) (GR73632) and [Lys3,Gly8-R-gamma-lactam-Leu9] NKA(3-10) (GR64349) are potent and selective agonists at NK-1 and NK-2 receptors respectively. In the guinea-pig isolated trachea preparation, contractions induced by these agonists were largely unaffected by inclusion of peptidase inhibitors in the bathing medium, indicating that these agonists are resistant to metabolism by peptidases. In the anaesthetised guinea-pig, both agonists were more potent bronchoconstrictor agents than either NKA or the SP analogue, SP methylester. In the anaesthetised rat, the NK-1 agonist, GR73632 was more potent than SP, NKA or NKB at causing the histamine-independent extravasation of plasma proteins into the skin after intradermal administration. The NK-2 agonist, GR64349 and the NK-3 agonist, senktide were without significant effect in this model. These agonists are useful tools for characterizing neurokinin receptor-mediated actions both in vitro and in vivo.

Evidence that the unilateral activation of 5-HT1D receptors in the substantia nigra of the guinea-pig elicits contralateral rotation.

1. The effects of various 5-hydroxytryptamine (5-HT) receptor agonists were examined following unilateral infusion into the substantia nigra (SN) of the guinea-pig. 2. The 5-HT1 receptor agonists, 5-carboxamidotryptamine (5-CT) (2-25 micrograms), sumatriptan (10-25 micrograms) and RU24969 (25 micrograms) all induced a marked contralateral rotation. In contrast, the selective 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH DPAT, 10-25 micrograms) produced only a very small response, whilst the selective 5-HT1C/5-HT2 receptor agonist (+-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride ((+/-)-DOI) (25 micrograms) and the 5-HT3 receptor agonist, 2-methyl 5-HT (2-Me5-HT, 25 micrograms) were without effect. 3. The contralateral rotation induced by 5-CT (10 micrograms) was attenuated following pretreatment with the non-selective 5-HT1/5-HT2 receptor antagonists methiothepin (1 mg kg-1, s.c.) and metergoline (5-10 mg kg-1, s.c.) but not the 5-HT1C/5-HT2 antagonist ritanserin (1 mg kg-1, s.c.) or the 5-HT3 antagonist, ondansetron (0.5 mg kg-1, s.c.). An involvement of dopaminergic systems in the rotational response to 5-CT was implied by the antagonism of 5-CT-induced rotation by haloperidol (0.3 mg kg-1, s.c.). 4. At doses lower than those required to produce contralateral rotation, 5-CT (0.08-0.4 micrograms) and sumatriptan (2 micrograms) induced a small, but nonetheless consistent, ipsilateral rotation. 5. The data with agonists and antagonists taken together suggest that 5-CT-induced contralateral rotation may be mediated by 5-HTID receptor activation but definitive classification of the receptor will not be possible until selective 5-HTID-antagonists become available. This may therefore represent the first model to study this receptor subtype in vivo.