Administration Of Aprotinin Research Articles

Influence of High-dose Aprotinin Treatment on Blood Loss and Coagulation Patterns in Patients Undergoing Myocardial Revascularization

Intraoperative administration of the proteinase inhibitor aprotinin causes reduction in blood loss and homologous blood requirement in patients undergoing cardiac surgery. To ascertain the blood-saving effect of aprotinin and to obtain further information about the mode of action, 40 patients undergoing primary myocardial revascularization were randomly assigned to receive either aprotinin or placebo treatment. Aprotinin was given as a bolus of 2 x 10(6) kallikrein inactivator units (KIU) before surgery followed by a continuous infusion of 5 x 10(5) KIU/h during surgery. Additionally, 2 x 10(6) KIU were added to the pump prime. Strict criteria were used to obtain a homogeneous patient selection. Total blood loss was reduced from 1,431 +/- 760 ml in the control group to 738 +/- 411 ml in the aprotinin group (P less than 0.05) and the homologous blood requirement from 838 +/- 963 ml to 163 +/- 308 ml (P less than 0.05). In the control group, 2.3 +/- 2.2 U of homologous blood or blood products were given, and in the aprotinin group, 0.63 +/- 0.96 U were given (P less than 0.05). Twenty-five percent of patients in the control group and 63% in the aprotinin group did not receive banked blood or homologous blood products. The activated clotting time as an indicator of inhibition of the contact phase of coagulation was significantly increased before heparinization in the aprotinin group (141 +/- 13 s vs. 122 +/- 25 s) and remained significantly increased until heparin was neutralized after cardiopulmonary bypass (CPB).(ABSTRACT TRUNCATED AT 250 WORDS)

The urinary excretion of epidermal growth factor in the rat is reduced by aprotinin, a proteinase inhibitor

The present study on the rat shows that i.v. administration of the proteinase inhibitor aprotinin reduces the urinary output of immunoreactive epidermal growth factor (EGF) while the amount of immunoreactive EGF in the kidneys is increased. This indicates that the EGF-precursor in the rat kidney in vivo is processed by an aprotinin inhibitable proteinase. EGF is produced in the kidneys as a precursor with a molecular weight of approximately 130 kDa. In rat urine, nanomolar amounts of 6 kDa EGF are excreted per 24 h together with small amounts of high molecular weight forms of EGF. During i.v. administration of aprotinin the median urinary output of immunoreactive EGF is reduced to 15% of the excretion of control rats (23 pmol/2 h versus 157 pmol/2 h, P < 0.001). Especially the excretion of 6 kDa EGF is reduced (median excretion 12 pmol/2 h versus 134 pmol/2 h, P < 0.001). The amount of immunoreactive EGF in the kidney tissue is increased after aprotinin administration (median amount 0.11 pmol EGF/mg protein versus < 0.04 pmol EGF/mg protein, P < 0.001). Neither the creatinine clearance, the total urinary protein output, nor the volume of urine produced was affected by aprotinin.

Akute eitrige Parotitis als Folge einer Alkylphosphat-(E 605)-Intoxikation

Acute suppurative parotitis is a possible consequence of poisoning by organophosphates (E 605). The endogenous accumulation of acetylcholine results--as in the acute pancreatitis caused by poisoning with organophosphates--in massive hyperemia and an increased secretory activity with leakage of saliva into the tissue, in an activation of the kallikrein-kinin system, the phospholipase A2, and, ultimately, in toxic tissue lesions caused by lysolecithin and the superoxide-radical anion. In spite of antibiotic therapy this is followed by bacterial inflammation. Treatment consists in the administration of aprotinin (Trasylol) and corticosteroids. In the case of abscess formation surgical drainage is necessary.

Aprotinin: An antidote for recombinant tissue-type plasminogen activator (rt-PA) active in vivo

The goal of the study was to assess if aprotinin, a protease inhibitor, could be used to antagonize in vivo the effects of recombinant tissue-type plasminogen activator (rt-PA). The time course of the lysis of a radioactive jugular vein thrombus was monitored continuously with an external gamma counter in anesthetized rabbits. Recombinant t-PA (0.25 mg) was given intravenously as a bolus injection (10% of the dose), followed by a 4 h infusion (90% of the dose). Rabbits received aprotinin 20 min after the start of the infusion as an intravenous bolus injection at a dose of 60,000 IU/kg (n = 4) or 20,000 IU/kg (n = 4).The rate of lysis in the different groups was compared 2, 60 and 180 min after aprotinin administration. Both doses of aprotinin immediately stopped thrombolysis. Thrombolysis was still blocked at 180 min with the highest dose but not with the lowest dose. Moreover, aprotinin could prevent the increase in bleeding time secondary to the injection of rt-PA. These results suggest that aprotinin might be used in vivo as an antidote for rt-PA.

Reduction of Blood Transfusion Requirement in Open Heart Surgery by Administration of High Doses of Aprotinin - Preliminary Results

Reduction of homologous blood requirement in cardiac surgery is of increasing interest and may be achieved by various technical and pharmacological means. High-dose aprotinin (about 840 mg, equivalent to 6 million Kallikrein inactivator units), a serine proteinase inhibitor, was administered during open heart surgery to 60 patients refusing homologous blood transfusions or suspected to have an increased risk of bleeding. As a significant decrease in donor blood requirement could be observed, a prospective, randomised double blind study in 80 male patients undergoing primary coronary surgery with high-dose aprotinin administration was performed. Mean blood loss was reduced by 45.9% (652 ml in the treated vs 1204 ml in the untreated group, p less than 0.01) and the mean amount transfused was decreased by 74.2% (242 ml vs 937 ml, p less than 0.01). No homologous blood was needed in 57.9% of the aprotinin-treated patients and in 31.6% of patients not treated with aprotinin.

Aprotinin reduces hypothermic mortality-an experimental model

In order to test the postulate that post-hypothermic damage may be caused by protease activation, the effect of the administration of aprotinin on hypothermic mortality was investigated in anaesthetized rabbits. A group of 6 animals received 40.000 KIU aprotinin intravenously prior to the induction of hypothermia by surface cooling and this was followed by a further 35.000 KIU each hour for 5 h. The animals were cooled to 29 degrees C and then rewarmed. A control group received equal volumes of physiological saline. The aprotinin treated animals survived, whereas all the control group died within 7 days, 5 of them within 24 h. The haemodynamic, biochemical and haematological changes in the two groups are reported.

Vasopressin: A model for the study of effects of additives on the oral and rectal administration of peptide drugs

We previously observed, using a relatively primitive assay, that small oral doses (on the order of 1 μg = 1 nmol = 1000 pmol per rat) of vasopressin can produce antidiuresis in hydrated rats, and that the oral activity was enhanced by simultaneous administration of an inhibitor of intestinal proteolysis. A more sensitive semi-automated computer-linked apparatus was used to conveniently and quickly compare the antidiuretic activities of the two natural and one synthetic vasopressin peptides by several routes of administration. (The approximate dose in pmol that resulted in a 50% decrease in urine flow is indicated in square brackets.) Intravenous lysine vasopressin was used as the benchmark dose [5]. Arginine and lysine vasopressin [3500], and the synthetic analogue, 1-deamino-8-D-arginine vasopressin (DDAVP) [20], were active by oral administration. The oral activities of arginine and lysine vasopressin were always enhanced by the simultaneous administration of aprotinin [1000], a natural inhibitor of trypsin; the effect of aprotinin on the oral activity of DDAVP was inconsistent. The vasopressins were more active when administered by the rectum: arginine vasopressin [20] and DDAVP [10]. The rectal activities of the peptides were increased by the absorption adjuvant, 5-methoxysalicylate (arginine vasopressin [10]; DDAVP [0.5]). The vasopressin peptides were also delivered by mouth in an impermeable coating of an azoaromatic cross-linked polymer, which is degraded by bacteria in the colon, to release the peptides in the upper colon for absorption (lysine vasopressin [525]). The use of the vasopressins as model peptide drugs has shown that although the efficacy of peptides is much less by the oral route and somewhat less by the rectal route than by parenteral administration, the effective doses are still very small, indicating that biologically potent peptide drugs can be administered by noninvasive routes.

Renal effects of aprotinin after 24 hours of unilateral ureteral obstruction

We have previously demonstrated that, after the release of 24-h unilateral ureteral obstruction (UUO), glomerular filtration rate (GFR), and renal blood flow (RBF) are reduced because of increased production of the potent vasoconstrictors thromboxane A2 (TxA2) and angiotensin II (ANG II). Captopril, which blocks ANG II production, increases GFR and RBF. Sequential administration of aprotinin, a kallikrein inhibitor, has an additive effect to further decrease renal vasoconstriction, even though kinins are generally thought to be vasodilators. Therefore, we assessed mechanisms by which aprotinin might improve renal function of previously obstructed anesthetized rats. When given alone to UUO rats, aprotinin improved renal hemodynamics. Since kinins stimulate TxA2 production by UUO kidneys perfused in vitro, our data suggest that aprotinin improved postobstructive function by decreasing kinin-stimulated TxA2 production, although this may not be its only effect. Aprotinin also improved postobstructive function, even if TxA2 formation was blocked with indomethacin. But when both ANG II and TxA2 formation were blocked by the simultaneous administration of captopril and indomethacin, aprotinin had no effect. This suggests that aprotinin may also affect ANG II formation. These pharmacological effects of aprotinin suggest that the kallikrein-kinin system may also contribute to postobstructive renal vasoconstriction by stimulating the production of both vasoconstrictor eicosanoids and ANG II.

High protection of animals lethally infected with influenza virus by aprotinin-rimantadine combination.

The successful therapeutic synergism of aprotinin and rimantadine, which are known to attack different viral targets, was demonstrated in influenza‐virus infected animals. Combined treatment with these drugs of mice infected with a highly lethal does of mouse‐adapted influenza virus prevented the development of separate administration of aprotinin and rimantadine induced 35% and 15% protection, respectively.

No Evidence on Significant Roles of the Prostaglandin-Thromboxane and Kallikrein-Kinin System in the Antihypertensive Effect of MK 421 in Rats Made Hypertensive by Norepinephrine or Vasopressin

Inhibition of angiotensin converting enzyme by MK 421 (6 mg/kg/day ip) induced a significant increase in urinary kinin excretion in norepinephrine-infused rats (1.8 mg/kg/day ip), whereas it had no effect on urinary prostaglandin E2 excretion. In contrast, MK 421 did not induced any significant changes in urinary kinin and prostaglandin E2 excretion in vasopressin-infused rats (7.2 U/kg/day ip). The simultaneous administration of indomethacin (10 mg/kg/day sc), OKY 046 (12 mg/kg/day sc) or aprotinin (100,000 units/kg/day sc) did not affect the antihypertensive effect of MK 421 in rats made hypertensive by chronic infusion of norepinephrine or vasopressin. The present results suggest that the hypotensive effect of MK 421 may depend on a reduced sensitivity of the vasculature to vasoconstrictor substances. In addition, it is also suggested that neither the prostaglandin-thromboxane or kallikrein-kinin systems are essential for the antihypertensive effect of MK 421 in these models of hypertension.

Dissociation of urinary kallikrein activity and salt and water excretion in the rat

Experiments were designed to examine the relationship, if any, between urinary kallikrein activity (amidolytic assay) and sodium and water excretion in 12-wk-old Munich-Wistar rats. Five groups of animals were studied: euvolemic, saline-expanded and water-loaded anesthetized rats, and euvolemic and saline-expanded conscious restrained rats. Following surgery, animals were allowed to stabilize (60-180 min) and reach a steady-state urine flow. By design, basal sodium and/or water excretion varied markedly among groups as a function of hydration state. Group means for sodium excretion and urine flow ranged from 0.8 to 12.4 mu eq/min and 6 to 112 microliter/min, respectively. In contrast, neither active nor total urinary kallikrein activity differed significantly among the five groups. In anesthetized euvolemic rats, intravenous administration of aprotinin produced a dose-dependent decrease in urinary kallikrein activity. The greatest inhibition of 93 +/- 3% (active) and 72 +/- 10% (total) was observed with a dose of 5,000 kallikrein inhibiting units (KIU)/kg and 1,000 KIU X kg-1 X min-1. This dose produced a significant decrease in active and total kallikrein activity in each group (P less than 0.001). However, sodium and water excretion were unchanged in aprotinin-treated rats and similar to values in vehicle-treated time-control groups. Linear regression analysis revealed no significant correlations between urinary kallikrein activity and sodium excretion or urine flow either among or within groups. These results indicate that urinary kallikrein activity is not related to acute sodium and water homeostasis in anesthetized or conscious rats.

Twenty-Four Hour Blood Glucose Profiles during Insulin and Insulin Plus Aprotinin Subcutaneous Administration in Type I Diabetes

Twenty-four hour glucose levels were measured in nineteen insulin treated type I diabetics both during insulin plus aprotinin treatments and insulin by itself. Aprotinin--a proteinase inhibitor agent--administered together with insulin (10.000 KIU for every 10 U.I. insulin) did not influence the effect of insulin on blood glucose levels. These findings do not support the hypothesis that the administration of aprotinin together with insulin can be clinically useful in conventional insulin treated diabetic patients.

The kallikrein-kinin system as mediator in vasogenic brain edema

Evidence has previously been provided that administration of kinins to the cerebrum causes edema and opening of the blood-brain barrier. It has further been shown that these highly active compounds are formed in the brain under pathophysiological conditions. Their formation was enhanced when cerebral blood flow became compromised by an increase in intracranial pressure. Final evidence, however, was not available as to whether specific inhibition of the kallikrein-kinin (KK) system has a therapeutic function in acute head injury. The authors have demonstrated in rabbits that inhibition of the activating enzyme kallikrein by aprotinin or by aprotinin plus soybean trypsin inhibitor (SBTI), which interfere with plasma and tissue kallikrein, is associated with a decrease in formation of posttraumatic swelling after a standardized cold lesion to the brain. Saline-treated control animals with cerebral cold-induced injury had an increase in hemispheric weight 24 hours later of 13.0% +/- 0.8% (standard error of the mean) in the damaged hemisphere compared to the contralateral nondamaged hemisphere. Administration of aprotinin or aprotinin plus SBTI led to a significant reduction of hemispheric swelling of 10.1% +/- 0.7% or 10.4% +/- 0.7%, respectively. In animals receiving SBTI only, hemispheric swelling evolving from cold injury was not significantly reduced. Therapeutic reduction of brain edema by aprotinin cannot be attributed to a nonspecific effect on the blood pressure, which in the experimental groups remained almost normal as compared to the control animals. Failure of SBTI to influence posttraumatic brain swelling may have resulted from disturbances in intravascular coagulation. Measurements of aprotinin in plasma and tissue demonstrate that the inhibitor doses employed are within an effective therapeutic range. Attenuation of brain edema by specific inhibition of the KK system provides evidence for a mediator role of kinins in vasogenic edema. Clinical trials with inhibitors of the KK system in acute forms of traumatic lesions associated with vasogenic edema appear worthwhile.

Aprotinin does not add protective effect to cold cardioplegia during coronary artery bypass surgery

The effect of aprotinin on intraoperative and postoperative CK-MB and left ventricular contractility in terms of dp/dt response to atrial pacing up to 150 beats/min was studied in 20 patients randomized before aortocoronary bypass surgery to either aprotinin or placebo administration. Cold cardioplegia and topical deep hypothermia were used in both groups. No difference could be demonstrated between the aprotinin and the placebo group, and the authors therefore concluded that aprotinin does not add substantially to the protective effect of cold cardioplegia and deep topical hypothermia during aortocoronary bypass surgery.

Mineralocorticoid escape during kallikrein inhibition

Kinins have been considered to be involved in the escape from the sodium retaining effects of mineralocorticoids. In a metabolic study in rats, the importance of the kallikrein-kinin system for sodium and potassium excretion was evaluated by aprotinin-induced kallikrein inhibition under basal conditions and during DOCA administration. Kallikrein inhibition was accompanied by a transient sodium retention. The escape from the sodium retaining effect of DOCA was not affected. However, the DOCA-induced potassium loss was enhanced. Kallikrein inhibition decreased urinary prostaglandin (PG) E2 and prevented the DOCA-induced rise in PGE2. Plasma renin activity was stimulated after 10 days of aprotinin administration. The kallikrein-kinin system is not an important mediator of the escape phenomenon but it may play a role in the regulation of sodium and potassium excretion.

Inhibition of the kallikrein-kinin system and vascular reactivity in Bartter's syndrome.

To study the significance of the increased activity of the kallikrein-kinin system described in patients with Bartter's syndrome, we investigated the pressor response to infused angiotensin II in four patients with the syndrome receiving no treatment and during the administration of aprotinin and of indomethacin. Five normal subjects served as controls. Aprotinin is a proteolytic enzyme that inhibits the formation of kinins by inhibiting plasma and glandular kallikrein. Indomethacin, a prostaglandin-synthesis inhibitor, can also inhibit the kallikrein-kinin system and normalizes vascular responsiveness to angiotensin II in Bartter's syndrome. All patients had increased urinary kallikrein and prostaglandin E2 concentrations. Aprotinin significantly decreased the dose of infused angiotensin II required to induce a 20 mm Hg increase in diastolic blood pressure, from 11 +/- 4 ng/kg/min to 7.0 +/- 2.0 ng/kg/min (mean +/- SD; p less than 0.05) in normal subjects and from 135 +/- 57 ng/kg/min to 70 +/- 26 ng/kg/min (p less than 0.05) in the patients with Bartter's syndrome, without significantly changing plasma renin activity, mean control blood pressure, or urinary prostaglandin E2 concentration. Indomethacin normalized the pressor response to angiotensin II in three patients who had been pretreated for 4 days (pressor dose, 10 ng/kg/min) but not in one patient who received a single oral dose of indomethacin 5 hours before the test. Our results suggest that inhibition of the kallikrein-kinin system alone accounts for approximately a 50% decrease in vascular resistance to the pressor effect of angiotensin II in Bartter's syndrome, while additional suppression of prostaglandins entirely normalizes the vascular response to angiotensin II.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of aprotinin on fibrinopurulent peritonitis in rats

The effect of aprotinin on the clinical and pathologic course of experimentally induced peritonitis in the rat was studied. Peritonitis was induced in 40 rats by creating a closed ileal loop 4 cm long 5 cm from the ileocecal valve. The rats were divided into two groups of 20 rats each. Group 1 served as a control group, whereas each animal in Group 2 received a bolus dose of aprotinin (10 ml) intraperitoneally immediately after closing the laparotomy. In the aprotinin-treated group, survival was drastically increased (p < 0.01) and formation of adhesions and abscesses was considerably reduced. The results of peritoneal cultures showed a decreased incidence of Escherichia coli and Clostridia in the aprotinin-treated group. We conclude that the administration of aprotinin significantly prolongs the survival time of animals with peritonitis and reduces the development of adhesions and abscesses in the peritoneal cavity. This beneficial effect can be attributed to decreased fibrinogen deposits within the peritoneal cavity and the stabilization of the organism after bacterial shock. Thus, bacteria were more susceptible to cellular and noncellular clearing mechanisms.

Captopril enhances aminoglycoside nephrotoxicity in potassium-depleted rats

We demonstrated that potassium depletion significantly increased gentamicin nephrotoxicity in Sprague-Dawley rats (100 mg X kg-1 X day-1). To determine whether this enhanced toxicity was mediated by renin secretion, we evaluated the effect of a converting enzyme inhibitor in this model. When we administered the combination of captopril (100 mg X kg-1 X day-1) and gentamicin in potassium-depleted rats, we observed a surprising and significant adverse effect of this combination on the clearances of inulin (CIn) and PAH (CPAH) and renal blood flow (RBF). Pretreatment with indomethacin significantly improved CIn and CPAH, and potassium repletion abolished this effect entirely. In potassium-depleted animals that received both gentamicin and captopril, the intra-arterial administration of imidazole, a thromboxane synthetase inhibitor, significantly reduced urinary TXB2 excretion and significantly improved RBF and CIn in vivo. In the same group of animals, administration of the kallikrein antagonist aprotinin also significantly increased both RBF and CIn. To measure total renal thromboxane B2 production (TXB2), we perfused kidneys ex vivo with cell-free perfusate. Three groups of animals were studied: potassium-repleted control animals, potassium-depleted control animals, and potassium-depleted animals treated with gentamicin alone, captopril alone, or the combination of gentamicin and captopril. We measured TXB2 in renal venous effluent by radioimmunoassay. Ex vivo perfused kidneys from potassium-depleted control animals produced significantly more TXB2 than potassium-repleted controls. Kidneys from potassium-depleted animals that received both gentamicin and captopril produced significantly greater amounts of TXB2 than did kidneys from potassium-depleted animals treated with captopril alone, gentamicin alone, or control potassium-depleted kidneys. The administration of imidazole ex vivo at a rate equivalent to in vivo administration (10 microM/min) reduced TXB2 production by potassium-depleted kidneys that received the combination of gentamicin and captopril to that of potassium-repleted control kidneys. These results suggest that the deleterious effect of captopril in potassium-depleted rats that received gentamicin is due at least in part to kinin-stimulated renal TXB2 production.

The antihypertensive function of the kidney. Its elucidation by captopril plus unclipping.

Unclipping the one-kidney, one-clip hypertensive rat during a free flow of urine caused the blood pressure to return to normal levels within about 3 hours. We found that administration of captopril plus unclipping caused the blood pressure to return to normal in minutes (17 +/- 4). Ureterocaval anastomosis plus captopril plus unclipping also caused the blood pressure to return to normal in minutes (8.8 +/- 2). Thus, the potentiation of the drop in blood pressure does not seem to be due to a volume effect. Administration of indomethacin and aprotinin did not prevent a rapid decline of the blood pressure after unclipping, but the decline was less rapid than that occurring after captopril and unclipping, which suggests that prostaglandin may have some effect on this mechanism. Saralasin administration did not potentiate the antihypertensive action of captopril plus unclipping. Chemical papillectomy prevented the drop in blood pressure after unclipping. The bolus dose of captopril to the hypertensive rat often caused a transient depressor effect resembling that due to the antihypertensive neutral renomedullary lipid, which suggests secretion of this lipid into the blood. The renomedullary interstitial cells accumulated large lipid granules after captopril administration. These cells also degranulated after unclipping. These findings are consistent with the hypothesis that the renal papilla secretes an antihypertensive hormone after unclipping. At present, antihypertensive neutral renomedullary lipid is the main putative hormone.

Clinical application of inhibitors of fibrinolysis.

The basic proteinase inhibitor from bovine organs, aprotinin, was first identified in 1930 and its effect on enzyme and other biological systems has since been extensively studied. Aprotinin can only be administered intravenously and has a half-life of about 2 hours. Its administration at the start of cardiopulmonary bypass surgery appears to reduce blood loss and to protect against global myocardial ischaemia. Similarly, a smaller infarct size seems to result from early administration of aprotinin within the first hour after myocardial infarction, though further studies are needed to confirm this effect. A combination of aprotinin with tranexamic acid may be effective in preventing or delaying rebleeding after rupture of an intracerebral aneurysm; the addition of aprotinin seems to decrease the incidence of delayed cerebral vasospasm and ischaemic complications which are sometimes noted when tranexamic acid alone is used. Aprotinin is also effective as adjuvant treatment in traumatic haemorrhagic shock. The recommended loading dose is 15,000 to 20,000 KIU/kg bodyweight administered as a short intravenous infusion, followed by 50,000 KIU/hour by continuous infusion. Side effects of aprotinin are very rare. Epsilon-Aminocaproic acid (EACA), p-aminomethylbenzoic acid (PAMBA) and tranexamic acid are synthetic antifibrinolytic amino acids. Saturation of the lysine binding sites of plasminogen with these inhibitors displaces plasminogen from the fibrin surface. On a molar basis tranexamic acid is at least 7 times more potent that epsilon-aminocaproic acid and twice as potent as p-aminomethylbenzoic acid. All 3 compounds are readily absorbed from the gastrointestinal tract and excreted in active form in the urine. The plasma half-life of tranexamic acid is about 80 minutes. The main indications for tranexamic acid are the prevention of excessive bleeding after tonsillectomy, prostatic surgery, and cervical conisation, and primary and IUD-induced menorrhagia. It is possible that gastric and intestinal bleeding can also be reduced as well as recurrent epistaxis. Tranexamic acid could also be useful after ocular trauma. The value of fibrinolysis inhibitors in the prevention of bleeding after tooth extraction in patients with haemophilia is well documented, as is the treatment of hereditary angioneurotic oedema. The usual dose of tranexamic acid is 0.5 to 1g (10 to 15 mg/kg bodyweight) given intravenously 2 to 3 times daily, or 1 to 1.5 g orally 3 to 4 times daily. This dose needs to be reduced in patients with renal insufficiency. The main side effects of tranexamic acid are nausea or diarrhoea.