Adaptation of the illness trajectory framework to describe the work of transitional cancer survivorship

PURPOSE/OBJECTIVES

To examine and refine the Illness Trajectory Framework, and to address transitional cancer survivorship.

DATA SOURCES

CINAHL®, PubMed, and relevant Institute of Medicine reports were searched for survivors' experiences during the year following treatment.

DATA SYNTHESIS

Using an abstraction tool, 68 articles were selected from the initial search (N > 700). Abstracted data were placed into a priori categories refined according to recommended procedures for theory derivation, followed by expert review.

CONCLUSIONS

Derivation resulted in a framework describing the work of transitional cancer survivorship, defined as survivor tasks, performed alone or with others, to carry out a plan of action for managing one or more aspects of life following primary cancer treatment. Theoretically, survivors engage in three reciprocally interactive lines of work: (a) illness-related, (b) biographical, and (c) everyday life work. Adaptation resulted in refinement of these domains and the addition of survivorship care planning under "illness-related work."

IMPLICATIONS FOR NURSING

Understanding this process of work may allow survivors and those who support them to better prepare for the post-treatment period. This adaptation provides a framework for future testing and development. Validity and utility of this framework within specific survivor populations also should be explored.

Cancer support and resource needs among African American older adults

Older African Americans face substantial barriers to state-of-the-art cancer care. Implementing culturally appropriate support throughout cancer therapy is critical to improving cancer outcomes and quality of life for this vulnerable population. The purpose of this study was to obtain experiential data regarding cancer diagnosis and treatment, and analyze survivors' recommendations regarding treatment-related needs, psychosocial support, and strategies and resources. Four main issues emerged from the study: (a) the need for more health-related and cancer-specific education, (b) the importance of faith and spirituality, (c) the availability of support, and (d) participants' difficulty identifying and articulating financial needs. Few participants reported requesting or receiving assistance (financial or otherwise) outside of the family during their cancer experience. However, treatment-related medication costs posed a significant hardship for many.

Nursing children after a disaster: a qualitative study of nurse volunteers and children after the Haiti earthquake

PURPOSE

The purpose of this study was to explore the experiences of nurse volunteers caring for children after the Haiti earthquake in January 2010.

DESIGN AND METHODS

This descriptive qualitative study using in-depth interviews focuses on the experiences of 10 nurse volunteers.

RESULTS

Four themes emerged: hope amid devastation, professional compromises, universality of children, and emotional impact on nurses.

PRACTICE IMPLICATIONS

Nurses who volunteer after natural disasters have rich personal and professional experiences, including extremes of sadness and joy. Nurse volunteers will likely need to care for children. Nurses and humanitarian agencies should prepare for the unique challenges of pediatric care.

Exploring the role of community health workers in providing cancer navigation: perceptions of African American older adults

PURPOSE/OBJECTIVES

To obtain experiential data regarding African American older adult survivors' perceptions of and recommendations on the role of community health workers (CHWs) in providing a cancer navigation intervention.

RESEARCH APPROACH

Focus groups.

SETTING

Rural Virginia and urban Maryland.

PARTICIPANTS

48 African American solid-tumor cancer survivors, aged 65 years or older, with Medicare insurance.

METHODOLOGIC APPROACH

Analysis was accomplished through a reflexive process of transcript review, categorization, and interpretation.

FINDINGS

Themes and accompanying categories identified were uneasiness surrounding the CHW role (disconnect between identified support needs and CHW role, essential CHW characteristics, and potential application of CHWs), recommendations to adequately address cancer needs (coordinating cancer treatment and unmet needs during cancer), and the importance of individualized interventions. Participants provided specific recommendations regarding the role of the CHW and how to develop supportive interventions.

CONCLUSIONS

Study participants had surprisingly limited prior exposure to the CHW role. However, they stated that, in certain circumstances, CHWs could effectively assist older adult African Americans undergoing cancer diagnosis or treatment.

INTERPRETATION

Study findings can be helpful to researchers and to healthcare providers engaged in assisting older African Americans during cancer diagnosis and treatment. The results lay a foundation for developing culturally appropriate interventions to assist this at-risk population.

Working through grief and loss: oncology nurses' perspectives on professional bereavement

PURPOSE/OBJECTIVES

To determine facilitators and barriers to managing patient loss from the combined perspectives of oncology nurses and to extract essential components of a supportive intervention.

RESEARCH APPROACH

Qualitative, descriptive.

SETTING

The comprehensive National Cancer Institute-designated cancer center of a mid-Atlantic university teaching hospital.

PARTICIPANTS

34 nurses from inpatient and outpatient adult and pediatric oncology units.

METHODOLOGIC APPROACH

Focus groups were held with oncology staff nurses to identify challenges regarding work-related bereavement, current support for managing grief and loss, and how to support interpersonal functioning and resiliency.

MAIN RESEARCH VARIABLES

Work-related bereavement, bereavement support, and interventions and management strategies for bereavement and loss.

FINDINGS

Two primary themes emerged: dimensions of work-related loss and working through bereavement. Participants also provided many concrete suggestions for the creation of a supportive self-care environment.

CONCLUSIONS

Support issues were numerous, multilevel, and varied. However, addressing those concerns can improve job satisfaction and decrease compassion fatigue. The findings lay the foundation for appropriate interventions to assist nurses in managing those situations.

INTERPRETATION

Administrators, managers, and individuals interested in furthering the multifaceted goals of oncology care, including nurses themselves, are challenged to create and maintain mutually supportive environments for providing optimal care to patients and families.

Insurance-related and financial challenges reported by managed care enrollees with breast cancer

Cancer survivors in the United States often encounter significant challenges in obtaining and paying for medical care. Multiple research studies have examined these issues in Medicare and Medicaid populations and the underinsured, but very little is known about insurance-related challenges encountered by cancer survivors enrolled in private insurance programs such as managed care. This secondary analysis of data explored the insurance-related and financial challenges reported by women enrolled in a managed care organization during cancer treatment and early follow-up. The researchers reviewed semistructured interviews with 14 women with breast cancer near the time of diagnosis, midway through treatment, and after treatment completion. Most women reported considerable stress related to performance of insurance-related tasks during or immediately after treatment, which resulted in negative emotional and psychological experiences. This article presents recommendations for how oncology nurses can intervene to assess and address these challenges and their effects. Future research should examine best practices related to nursing management of insurance-related and financial challenges during cancer.

The phosphoryl oxime-destroying activity of human plasma

The potential of obidoxime and other pyridinium-4-aldoximes to reactivate dimethyl- and diethylphosphorylated cholinesterases is markedly restricted by the inevitable formation of rather stable phosphoryl oximes (POXs) with high anticholinesterase activity. This effect is hardly seen with very dilute enzyme preparations, but becomes significant at physiological enzyme concentrations. Human plasma with the butyrylcholinesterase irreversibly blocked by soman was able to stimulate obidoxime-induced reactivation of concentrated erythrocyte acetylcholinesterase (Ery-AChE) to the same extent as was observed with a dilute preparation, suggesting phosphoryl oxime-destroying capacity. The inactivating factor, which was tentatively termed POX-hydrolase, had (1) a molecular weight of >100 kDa; (2) required Ca2+ , which could not be substituted by Zn2+ or Mg2+; and (3) lost its catalytic activity reversibly in the presence of ethylenediamine-tetraacetic acid (EDTA). The enzyme activity varied widely (20-fold) among different subjects and did not follow the activity pattern of human serum paraoxonase (PON1). Rabbit plasma with its particularly high paraoxonase content showed only weak POX-hydrolase activity. These data suggest POX-hydrolase to be a different entity. POX-hydrolase was most active with the putative phosphoryl-obidoxime from paraoxon-ethyl, less with the product from paraoxon-methyl and least with that from diisopropylfluorophosphate. The analogue TMB-4 reacted similarly to obidoxime. The putative phosphonyl oximes arising by the reaction of obidoxime with nerve agents were apparently not cleaved. The variation in POX-hydrolase activity may additionally contribute to the variable response to oxime therapy in patients with organophosphate insecticide poisoning.

Cholinesterase status, pharmacokinetics and laboratory findings during obidoxime therapy in organophosphate poisoned patients

1 The effectiveness of oxime therapy in organophosphate poisoning is still a matter of debate. It appears, however, that the often cited ineffectiveness of oximes may be due to inappropriate dosing. By virtue of in vitro findings and theoretical considerations we concluded in the preceding paper that oximes should preferably be administered by continuous infusion following an initial bolus dose for as long as reactivation of inhibited acetylcholinesterase (AChE) can be expected. This conclusion has called for a clinical trial to evaluate such oxime therapy on the basis of objective parameters. 2 Before transfer to the intensive care unit (ICU), 5 patients received primary care by an emergency physician. In the ICU, atropine sulphate was administered i.v. upon demand according to the endpoints: no bronchorrhoea, dry mucous membranes, no axillary sweating, heart rate of about 100/min. Obidoxime (Toxogonin) was given as an i.v. bolus (250 mg) followed by continuous infusion of 750 mg/24 h. 3 Intoxication and therapy were monitored by determining erythrocyte AChE (eryAChE) activity, reactivatability of the patient's eryAChE ex vivo, plasma cholinesterase activity, the presence of AChE inhibiting compounds, as well as the concentrations of obidoxime and atropine in plasma. 4 Obidoxime was effective in life-threatening parathion poisoning, in particular when the dose absorbed was comparably low. In mega-dose poisoning, net reactivation was not achieved until several days after ingestion, when the concentration of active poison in plasma had declined. Reactivatability in vivo lasted for a longer period than expected from in vitro experiments. 5 Obidoxime was quite ineffective in oxydemetonmethyl poisoning, when the time elapsed between ingestion and oxime therapy was longer than 1 day. When obidoxime was administered shortly after ingestion (1 h) reactivation was nearly complete. 6 Obidoxime levels of 10-20 microM were achieved by our regimen, and atropine could rapidly be reduced to approx. 20 microM, as attained by continuous infusion of 1 mg atropine sulphate/h. Maintenance of the desired plasma levels was not critical even when renal function deteriorated. 7 Signs of transiently impaired liver function were observed in patients who showed transient multiorgan failure. In the present stage of knowledge, we feel it advisable to keep the plasma concentration of obidoxime at 10-20 microM, although the full reactivating potential of obidoxime will not then be exploited. Still, the reactivation rate, with an apparent half-time of some 3 min, is twice that estimated for a tenfold higher pralidoxime concentration.

Reappraisal of indications and limitations of oxime therapy in organophosphate poisoning

1 In vitro studies with human erythrocyte acetylcholinesterase (AChE) and the mouse diaphragm model were performed to unravel the various microscopic reaction parameters that contribute to the dynamic equilibrium of AChE inhibition, ageing and reactivation. These data may help to define more precisely the indications and limitations of oxime therapy in organophosphate (OP) poisoning. 2 Diethylphosphoryl-AChE resulting from intoxications with parathion, chlorpyrifos, chlorfenvinphos, diazinon and other OPs is characterized by slow spontaneous reactivation and low propensity for ageing. This kind of phosphorylated enzyme is particularly susceptible to reactivation by oximes. 3 None of the oximes tested (pralidoxime, obidoxime, HI 6 and HLö 7) can be regarded as a universally suitable reactivator. Obidoxime turned out to be the most potent and most efficacious oxime in reactivating AChE inhibited by various classes of OP insecticides and tabun. Obidoxime, however, was inferior to HI 6 against soman, sarin, cyclosarin and VX. Pralidoxime was generally less potent. 4 The kinetic data of reactivation established for diethylphosphoryl-AChE of human red cells indicate that the usually recommended dosage to attain a plasma concentration of 4 micrograms/ml does not permit exploitation of the full therapeutic potential of the oximes, in particular of pralidoxime. However, in suicidal mega-dose poisoning, oximes, even at optimal plasma concentrations, may be unable to cope with the fast re-inhibition of reactivated AChE in the first days following intoxication. 5 It is suggested that oximes be administered by continuous infusion following an initial bolus dose as long as reactivation can be expected and until permanent clinical improvement is achieved.

Pharmacokinetics of atropine in dogs after i.m. injection with newly developed dry/wet combination autoinjectors containing HI 6 or HLö 7

To cope with the rapid onset of the life-threatening cholinergic crisis after poisoning with organophosphorus compounds, atropine-oxime preparations should be available in autoinjectors allowing i.m. administration also in the absence of a physician. Such a scenario is conceivable in the battlefield, when nerve agents are disseminated, and can no longer be excluded in civilian areas, as demonstrated most recently in Tokyo. In addition, autoinjectors may be of value in agriculture when medical care is remote. The use of second generation oximes with broad antidotal spectrum, e.g., HI 6 (1-(((4-(aminocarbonyl)pyridinio)methoxy)methyl)-2-((hydr oxyimino)methyl) pyridinium dichloride monohydrate; CAS 34433-31-3) and HLö 7 (1-(((4-(aminocarbonyl)pyridinio)methoxy)methyl) 2,4-bis((hydroxyimino)methyl) pyridinium dimethanesulfonate; CAS 145613-73-6) is only possible in dry/wet autoinjectors because their stability is limited in concentrated solution. To detect a possible delay in atropine absorption by the two oximes, the pharmacokinetics of atropine after "autoinjection" in beagle dogs were determined. Commercially available autoinjectors from two manufacturers [STI International Ltd (BJ) and Astra Tech (AT)] were filled with atropine sulfate, either alone (2 mg) or in combination with HI 6 (500 mg) and HLö 7 (200 mg), respectively, and injected according to a complete cross-over design. Atropine concentration was determined as l-hyoscyamine equivalents in a radioreceptor assay (RRA). In the range of 0.1-6.9 ng/ml, atropine sulfate displaced [N-methyl-3H]-scopolamine methyl chloride ([3H]NMS) competitively from rat cerebral cortex membranes. At 200 pmol/l [3H]NMS, IC50 was 1.4 +/- 0.1 x 10(-9) M atropine (CV = 8.1%). The intra-assay deviation was about 6%; day-to-day deviation in determination of 1 nM (0.695 ng/ml) atropine was 2.6% (CV = 5.2%). AT autoinjectors containing HI 6 delivered only 1.81 mg atropine sulfate while 2.14 mg was released by the other injectors. According to the manufacturer, the reduced delivery was caused by a defective Teflon-coated O-ring as detected later on in the batch used. To allow comparison of the bioavailability of atropine from various autoinjectors, the AUCs were normalized to a constant dose. The atropine absorption half-time (7 min) was not affected either by the autoinjector type or by the combination with oximes. The other pharmacokinetic data likewise did not reveal any differences between the groups. Maximal plasma concentration was 33 ng ml-1, elimination half-life 52 min, Vapp 3.2 l kg-1 and Clpl 44 ml min-1 kg-1. The relatively high clearance of l-hyoscyamine is discussed.

Effects of atropine and soman on the pharmacokinetics of the oxime HLö 7 dimethanesulfonate in anesthetized guinea-pigs

The respiratory and circulatory effects and the pharmacokinetics of the bispyridinium dioxime HLö 7 (30 mumol/kg) were investigated in guinea-pigs in combination with atropine (28.8 mumol/kg) or with atropine plus soman (0.44 mumol/kg = 5 x LD50). The pharmacokinetics and pharmacodynamics were studied in separate groups of animals. HLö 7 had only minor effects on circulation and respiration. HLö 7 plus atropine caused a transient, pronounced fall of blood pressure, tachycardia, and respiratory stimulation. The soman-induced bradycardia was completely restored by the antidotes, while respiration improved within a few minutes with the respiratory rate becoming stabilized at 50% of baseline. Plasma half-time (60-70 min), plasma clearance (6-7 ml.kg-1.min-1) and apparent volume of distribution (0.5-0.6 l/kg) of HLö 7 did not differ between the groups, i.e. atropine and soman did not affect the kinetics of the oxime.

Pharmacokinetics of the oximes HI 6 and HLö 7 in dogs after i.m. injection with newly developed dry/wet autoinjectors

The rapid onset of cholinergic crisis after intoxication with highly toxic organophosphorus compounds calls for pre-clinical administration of effective antidotes as early as possible. For this purpose, i.m. administration of the antidotes by autoinjectors is desired to allow early treatment also in the absence of a physician. Besides atropine, oximes with broad antidotal spectrum are considered valuable adjuncts that should be included in antidotal mixtures. To circumvent the problem of limited stability of the new-generation oximes, dry/wet autoinjectors were developed in which the unstable solid is dissolved by a diluent in an adjacent chamber upon activation of the device. In this study the tolerance, bioavailability and pharmacokinetics of 500 mg HI 6 [1-(((4-(aminocarbonyl) pyridinio)methoxy) methyl)-2-((hydroxyimino)methyl) pyridinium dichloride monohydrate] or 200 mg HLö 7 [1-(((4-(aminocarbonyl) pyridinio)methoxy)methyl)-2,4- bis((hydroxyimino)methyl)pyridinium dimethanesulfonate] in combination with 2 mg atropine sulfate versus atropine alone, delivered by two dry/wet autoinjector types, were investigated in eight male beagle dogs (16 kg) in a complete cross-over design. The dogs tolerated the six injections with 3-week intervals without any symptoms of discomfort. Nonetheless, CPK activity increased, peaking at 6 h after injection. In contrast to atropine which merely led to a marginal increase, HI 6 plus atropine increased the baseline CPK activity about 10-fold, and HLö 7 plus atropine about 20-fold, regardless of the injector type. The HI 6 autoinjectors from Astra Tech were from an irregular production batch which did not deliver the declared HI 6 dose. The HLö 7 autoinjectors from Astra Tech and both Binaject autoinjectors from STI functioned well: the bioavailability was complete with tmax values of about 25 min as observed after conventional i.m. injection. The absorption half-time was about 8 min, elimination t1/2 about 50 min, and Vapp 0.26 l/kg. The urinary recovery of unchanged oximes was 70-80%, the renal clearance being the same as for inulin. Unexpectedly, hematocrit and hemoglobin content of blood decreased by about 15% within 2 h and reached pre-treatment values after 6-24 h. This decrease was observed with all three drug treatments and could not be accounted for by blood loss (< 4%), thus pointing to an atropine effect. In conclusion, the newly developed dry/wet autoinjectors appear suitable for the administration of atropine and an oxime stored in solid form.

Acute effects of the heavy metal antidotes DMPS and DMSA on circulation, respiration, and blood homoeostasis in dogs

The heavy metal antidotes sodium-2,3-dimercaptopropane-1-sulfonate (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) were investigated in anaesthetized dogs for their effects on a variety of physiological variables and parameters. In addition, the influence of both dithiols on oxygen consumption and ferrihaemoglobin production was studied in blood and red blood cells in vitro. DMPS (15 and 75 mg/kg i.v.) did not affect respiration, central venous pressure, left ventricular pressure or cardiac output and showed only marginal, statistically non-significant effects on aortic and effective perfusion pressure. In contrast to the slight, non-significant changes due to DMPS (15 mg/kg i.v.), an equimolar dose of DMSA (12 mg/kg i.v.) led to a slight transient decrease in femoral blood pressure with strong reflex tachycardia and increase in blood flow. The higher DMPS dose (75 mg/kg i.v.), however, caused marked decreases in femoral blood pressure and blood flow, strong changes in blood gases and pH, and lactacidosis. Most of the physiological variables and parameters did not return to the initial level by 60 min. The R-spike of the electrocardiogram decreased, and the T-wave increased. Experiments on the denervated hind leg indicate that DMPS may be a direct vasodilator. The fall of blood pressure due to DMPS was markedly reduced when 30% ferrihaemoglobin had been formed by 4-dimethylaminophenol.HCl (DMAP). The highest DMPS dose (150 mg/kg i.v.) provoked circulatory failure and respiratory arrest. Artificial ventilation with room air restored spontaneous respiration, but one of three animals did not survive this dose for more than 90 min. DMPS and DMSA reacted with oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

HLö 7 dimethanesulfonate, a potent bispyridinium-dioxime against anticholinesterases

HLö 7 dimethanesulfonate (1-[[[4-(aminocarbonyl)pyridinio]methoxy]methyl]-2,4-bis [(hydroxyimino)methyl]pyridinium dimethanesulfonate) is a broad-spectrum reactivator against highly toxic organophosphorus compounds. The compound was synthesized by a new route with the carcinogenic bis(chloromethyl)ether being substituted by the non-mutagenic bis(methylsulfonoxymethyl)ether. The very soluble dimethanesulfonate of obidoxime was also prepared by this way. HLö 7 dimethanesulfonate is the first water-soluble salt of HLö 7 that should be suitable for the wet/dry autoinjector technology, because aqueous solutions of HLö 7 are not very stable (calculated shelf-life 0.2 years when stored at 8 degrees C, 1 M solution, pH 2.5). The crystalline preparation contains 96% of the syn/syn-isomer, less than 2% of the syn/anti-isomer and some minor identified by-products. HLö 7 was very efficient in reactivating acetylcholinesterase (AChE) blocked by organophosphates as long as ageing did not prevent dephosphylation. HLö 7 was superior to HI 6 (1-[[[4-(aminocarbonyl)pyridinio]methoxy]methyl]-2- [(hydroxyimino)methyl]pyridinium dichloride) in reactivating soman and sarin-inhibited AChE from erythrocytes, and literature data indicate that HLö 7 exceeds HI 6 by far in reactivating tabun-inhibited AChE. In atropine-protected, soman-poisoned mice HLö 7 was three times more potent than HI 6 (protective ratio 5 versus 2.5), and in sarin-poisoned mice HLö 7 was 10 times more potent than HI 6 (protective ratio 8 for both oximes). In atropine-protected guinea-pigs HLö 7 was less effective than HI 6 (protective ratio: 2.3 versus 5.2 for soman; 5.2 versus 6.8 for sarin; 4.3 versus 3.8 for tabun). The mean survival time of anaesthetized guinea-pigs exposed to 5 LD50 soman (6.3 min) was increased by atropine (27 min) and atropine + HLö (57 min). HLö 7 alone did not prolong the survival. The most impressive effect of HLö 7 was on respiration: 3 min after i.v. injection of HLö 7 and atropine, the depressed respiration increased rapidly to 60% of control and remained at that level during the observation period (60 min). With atropine alone, respiration recovered only slowly. Behavioural and physiologic parameters were determined in atropine-protected mice exposed to a sublethal soman dose. The running performance was significantly improved by HLö 7. Even central symptoms, e.g. hypothermia and convulsions, were decreased markedly by HLö 7 (evaluation 60 min after poisoning). The pharmacokinetic data for HLö 7 in male beagle dogs are similar to those of HI 6.(ABSTRACT TRUNCATED AT 400 WORDS)

Bioequivalence and pharmacodynamics of a modified glibenclamide formulation in healthy volunteers

A glibenclamide preparation (Glycolande N) with a modified galenic formulation was compared with a marketed standard preparation for bioequivalence and hypoglycaemic action after single oral administration of 3.5 mg. Twelve healthy male volunteers participated in this open two-way cross-over study. The confidence intervals around the mean values of the standard preparation were all in the range of +/- 20%. No significant differences were found between both formulations for Cmax, Tmax, AUC1 and AUC3. The glucose profiles were virtually equal. Both preparations are regarded as bioequivalent and therapeutically equivalent.

Effects of amyl nitrite on circulation, respiration and blood homoeostasis in cyanide poisoning

The effects of intravenously (i.v.) administered or inhaled amyl nitrite (AN) were followed under chloralose anaesthesia in intact and cyanide-poisoned, spontaneously breathing beagles. The i.v. doses of AN were 0.03 and 0.15 mmol/kg and the i.v. dose of KCN was 0.06 mmol/kg. AN was inhaled in a closed system at 0.15 mmol/kg without previous poisoning and, in addition, at 0.074 mmol/kg (two ampoules at 0.3 ml AN) during artificial ventilation after poisoning with 0.045 mmol KCN/kg i.v.. Mean arterial pressure decreased by 15 and 40 mmHg, respectively, after i.v. injection of AN, associated with bradycardia and lowered peripheral blood flow. Respiratory minute volume rose by 65% with the higher dose. Arterial pO2 decreased by 20 mmHg while pCO2 rose by 6 mmHg. Within 30 min of injection, these changes were only partially reversible. Similar results were obtained following inhalation of AN in a closed system. Lactic acidosis and lowering of pH were produced by the i.v. route, but not by inhalation. Total haemoglobin increased. The lethality of KCN was abolished with AN doses that produced 10-30% ferrihaemoglobin. Artificial ventilation and simultaneous inhalation of AN after poisoning with lethal doses of KCN turned out to be ineffective therapeutic measures. The findings are compared with those of other papers dealing with cyanide poisoning and AN. It is pointed out that, for the present, there is no experimental proof for another antidotal mechanism of action of AN than ferrihaemoglobin formation.

Ferrihaemoglobin formation by amyl nitrite and sodium nitrite in different species in vivo and in vitro

The ferrihaemoglobin (HbFe3+) formation by amyl nitrite (AN) or sodium nitrite (NaNO2) was studied in different species including man, in vivo and in vitro. In in vivo studies AN was administered intravenously (i.v.), intramuscularly (i.m.), by inhalation, or orally. NaNO2 was injected i.v.. AN i.v. produced HbFe3+ much more rapidly than NaNO2 in dogs, cats, rabbits, and rats. In dogs, i.m. injection of AN was followed by a very slow linear increase in the HbFe3+ content. Inhalation of AN did not lead to HbFe3+ formation in dogs unless it was rebreathed in a closed (bag) or not completely open (gas mask) system. HbFe3+ was produced by oral AN in dogs, the effect being enhanced by addition of DMSO. Inhalation of AN by human volunteers in a gas mask and from ampoules crushed close to the nose did not induce haemoglobin oxidation to a practically significant extent, but it was associated with headache, tiredness, dizziness, and a fall in blood pressure. In in vitro studies, in contrast to NaNO2, AN produced HbFe3+ instantaneously in erythrocytes of various species and in purified human haemoglobin. AN 1 mol yielded 2 mol Fe3+. Only 20% of the oxygen released during the oxidation of haemoglobin by AN or NaNO2 was recovered. In 0.2 M phosphate buffer, pH 7.4, 0.01 mol O2/mol AN was consumed. CO2 was released in the presence of AN, but not of NaNO2, from blood, plasma, and 0.02 M NaHCO3 solution. The ratio (lactate)/(pyruvate) decreased when HbFe3+ was formed by AN or NaNO2.

Pharmacokinetics and pharmacodynamics of the oxime HI6 in dogs

The pharmacokinetics and pharmacodynamics of the oxime HI6 were investigated in conscious and anesthetized beagle dogs following intramuscular injection. The absorption of HI6 (100 mumol/kg) was slower in conscious dogs as compared to the anesthetized dogs, and the maximum concentrations in plasma were lower (200 instead of 300 mumol/l). In comparison, the elimination of HI6 (100 mumol/kg) was twice as rapid in the conscious dogs (ke = 0.013 instead of 0.006 min-1) as in the anesthetized animals and was equal to the elimination after injection of 50 mumol/kg (likewise in anesthesia). The more rapid elimination was accompanied by a greater renal excretion of unchanged HI6 (60% instead of 40% in 3 h). HI6 penetrated the blood-brain barrier. The concentration of the oxime in CSF increased rapidly during the absorption phase (by 30 min after injection). The maximum concentrations (1-3 mumol/l) were reached between 60 and 120 min. The peak concentrations in plasma and CSF did not correlate with each other. In the anesthetized dogs the higher dose of HI6 (100 mumol/kg) caused a steady decrease in mean blood pressure (20 mm Hg) and blood flow (50%) in the femoral artery and a fall in left ventricular pressure (20 mm Hg), lasting for at least 60 min; the lower dose (50 mumol/kg) did not cause circulatory effects. EKG, respiration, hematocrit, arterial blood gases, and pH were not influenced.

Pharmacokinetics and toxicity of the oxime HGG 12 in dogs

The pharmacokinetics, pharmacodynamics, and toxicity of the oxime HGG 12 were studied in conscious and anesthetized dogs. IV administration. The mean value of the half-time for terminal elimination of HGG 12 was 47 min; plasma clearance amounted to 4.6 ml kg-1 min-1 and Vapp to 0.315 1 kg-1. At doses above 1 mumol/kg heart rate, left ventricular pressure and mean arterial pressure decreased, while central venous pressure and femoral blood flow increased. The dose-response curves were very flat. Repetitive administration of various doses of HGG 12 in 30 min intervals did not enhance the negative chronotropic effect when the preceding total dose amounted to about 1 mumol/kg. IM administration. The half-times for the absorption of HGG 12 dichloride and HGG 12 dinitrate were about 3.5 min; the corresponding value for HGG 12 dibromide was 9.4 min. In the elimination phase the half-time was comparable with that of the IV experiments. About 60% of the oxime was excreted unchanged in the urine within 24 h. The circulatory changes showed the same tendency as after IV injection. Conscious dogs tolerated well daily doses of 10 mumol/kg for 6 weeks. At 30 mumol/kg all dogs survived, displaying symptoms reminiscent of a cholinergic syndrome. Five out of eight dogs survived at 90 mumol/kg. Macroscopic and microscopic examinations and blood chemistry data showed no abnormality.

Effects and biotransformation of 4-dimethylaminophenol in man and dog

The cyanide antidote 4-dimethylaminophenol . HCl (DMAP) was administered orally, i.v., or i.m. to man and dog. Ferrihemoglobin formation and changes of several parameters in human blood were investigated to obtain information on damage to liver, kidney, muscle, and red blood cells; in addition, the metabolism of DMAP was studied. In dogs, the initial rate of ferrihemoglobin production (DMAP, 3.25 mg/kg i.v. or i.m., 15 mg/kg orally) amounted to 28%, 3.5%, and 2% of the total hemoglobin per min; the corresponding values for man were 9%, 2%, and 2% per min. The dogs behaved normally while CPK increased after i.m. injection. In man, only i.m. injection of DMAP (3.25 mg/kg) was followed by increases in LDH, GOT, and CPK of 110, 260, and 490%, resp.; while total bilirubin, conjugated bilirubin, and iron concentration rose by 270, 120, and 50%, respectively. Bilirubin and iron concentration increased also after DMAP i.v. (3.25 mg/kg) or when it was taken orally (600 or 900 mg). The lactate concentration was not influenced while the pyruvate concentration increased by 50%. DMAP produced hemolysis in vitro. Generally, the values determined in vivo approached the starting level within 1 week. Intramuscular injection of DMAP induced reversible subjective and objective symptoms, e.g., local pain, swollen buttock, fever reaction. The urine showed no pathological changes. About 54% of DMAP taken orally was excreted as metabolites in the urine, 41% as glucuronide, 7% as sulfate, and 6% as thioethers. After i.v. administration the total of metabolites was somewhat higher, and the thioether proportion was 15%. The results indicate that DMAP is readily absorbed after oral administration but undergoes significant first pass effect in the liver. Therefore, the 4-fold i.v. dose must be administered orally to achieve the same ferrihemoglobin formation.

Effects of 4-dimethylaminophenol, Co2EDTA, or NaNO2 on cerebral blood flow and sinus blood homeostasis of dogs in connection with acute cyanide poisoning

The effects of the cyanide antidotes DMAP, Co2EDTA, and NaNO2 on cerebral blood flow (CBF) and cerebral blood gases were investigated in connection with acute poisoning of dogs by cyanide. The substances were injected intravenously. Local CBF as measured with thermocouples in the cingulum increased by 100-200% after a non-lethal dose of KCN (1 mg/kg) and by 50% after injection of NaNO2 (15 mg/kg), that oxidized some 20% of the total hemoglobin to ferrihemoglobin. Co2EDTA (10 mg/kg) induced a decrease in local CBF of 30% and in brain temperature of 0.5 degree C. The temperature diminished also after poisoning by KCN, but it rose by 0.15 degree C after the administration of NaNO2. Local CBF and sinus sagittalis blood flow increased by 60-160% for about 15 min, and the brain temperature decreased by 0.4-0.5 degree C when DMAP (3.25 mg/kg) or Co2EDTA (15 mg/kg) was injected 1 min after poisoning by cyanide (4 mg/kg), a dose that always caused respiratory arrest. Immediately after injection of DMAP the brain temperature rose transiently by 0.1-0.2 degree C. Co2EDTA did not exert such an effect. In the sinus sagittalis blood of artificially ventilated animals pCO2 decreased rapidly by 10-20 mmHg after poisoning and approached the initial level after treatment with DMAP or Co2EDTA. The highest value of pO2 was about 80 mmHg and 50 mmHg after injection of DMAP and Co2EDTA, respectively; thereafter pO2 declined to 20 mmHg or 40 mmHg at 20 min. The lactate concentration increased by 60-70% without tendency to return to normal.

Cerebral blood flow, circulation, and blood homeostasis of dogs during slow cyanide poisoning and after treatment with 4-dimethylaminophenol

The effects of 4-dimethylaminophenol . HCl (DMAP) and 100% oxygen on cerebral blood flow (CBF) and peripheral circulation, arterial and venous blood gases, and other parameters have been investigated in dogs in the course of slow cyanide infusion. The i.v. infusion of KCN increased the respiratory minute volume, accompanied by a rise in arterial pO2 and pH and a decrease in arterial pCO2 while the venous lactate concentration increased by about 500% and the hemoglobin content and hematocrit by about 30%. Heart rate and carotid artery blood flow decreased. Local CBF in the cingulum as measured with thermocouples rose steadily, and the brain and oesophagus temperature were lowered. The breathing of 100% oxygen raised the local CBF, the temperature, and the arterial pCO2. During the infusion of KCN into the femoral artery of artificially ventilated dogs the femoral venous pO2 increased continuously by some 40 mm Hg, attended with a decrease in pCO2 of 15 mm Hg. The femoral blood flow, however, rose sharply within 3 min. 100% oxygen induced a rise in pCO2 and a diminution of pH in the femoral vein and in the sinus sagittalis, and the femoral flow rose rapidly. After DMAP i.v. the values of most of the parameters returned to normal or finally stabilized below or above the initial level. The rise in the hemoglobin content, hematocrit, and lactate concentration was stopped, but the arterial and venous pH remained or were lowered. DMAP elicited a rapid, strong decrease in the pO2 of the femoral vein and the sinus sagittalis with a concomitant marked increase in pCO2.

Effects of 4-dimethylaminophenol on blood flow and blood gases in the brain

The effects of i.v. injected 4-dimethylaminophenol HCl, a ferri-hemoglobin-forming substance, on cerebral blood flow, brain temperature, blood gases, and lactate concentration in the sinus sagittalis blood were measured on male beagle dogs anesthetized with chloralose. An increase in cerebral blood flow became measurable when 5% or more of the hemoglobin was oxidized to ferrihemoglobin. The local cerebral blood flow of the cingulum region and the flow in the sinus sagittalis increased, while the sinus pO2 decreased. An increase in the ferrihemoglobin content of some 20% of the total hemoglobin at a constant arterial pO2 and pCO2 was attended with a decrease in the sinus pO2 of about 10 mm Hg when less than 40% of the heme iron was oxidized. The sinus pO2 approached a threshold value of some 8 mm Hg when the ferrihemoglobin content was increased above 40%. The lactate concentration began to rise very rapidly when 40-50% of the hemoglobin was oxidized. At the same time pCO2 increased and pH decreased in the sinus blood. The brain temperature remained unchanged. The behavior of conscious dogs with a ferrihemoglobin content of 40% of the total hemoglobin showed no abnormalities.

Circulation, respiration, and blood homeostasis in cyanide-poisoned dogs after treatment with 4-dimethylaminophenol or cobalt compounds

The effects of intravenously injected 4-dimethylaminophenol-HCl (DMAP), Co2EDTA, and Co(histidine)2 on the survival rate and several physiological parameters were studied on dogs after acute intravenous poisoning with the double lethal dose of potassium cyanide. All dogs survived when the antidotes were administered 1 min after poisoning. When the therapy began 4 min after poisoning more dogs were rescued in the DMAP group than in the cobalt groups. DMAP, Co2EDTA, and Co(histidine)2 restored circulation and respiration of the surviving animals in a similar manner. The increase in the plasma concentrations of glucose and lactate was much higher in the Co2EDTA group than in the DMAP group. The injection of Co2EDTA produced a sharp rise in the lactate-to-pyruvate ratio. The lactate-to-pyruvate ratio stayed unchanged for some 15 min after injection of DMAP before also rising. The total dose of KCN (4 mg/kg) was bound to the ferrihemoglobin formed by DMAP. The arterial pO2 increase, caused by liberation of oxygen from oxyhemoglobin during the formation of ferrihemoglobin, was less when the cyanide could act on the tissues for a longer period of time before the therapy with DMAP began. DMAP is more appropriate for the therapy of cyanide poisoning than Co2EDTA, since the latter adds its inhibitory effects on the metabolism to those of cyanide.

Effects of 4-dimethylaminophenol and Co2EDTA on circulation, respiration, and blood homeostasis in dogs

The effects of intravenously injected 4-dimethylaminophenol and Co2EDTA on peripheral circulation, respiration, acid-base balance, and several other physiological and biochemical parameters were studied on dogs. DMAP increased the respiratory minute volume and mean arterial pressure, diminished the lactate-to-pyruvate ratio, and induced an increase in arterial oxygen pressure caused by liberation of oxygen from oxyhemoglobin during the formation of ferrihemoglobin. A study in vitro of the fate of the oxygen during the reaction between DMAP and oxyhemoglobin showed that only 30--40% of the oxygen released by the formation of ferrihemoglobin appeared in the gas phase. Co2EDTA caused circulatory depression, hyperventilation, and metabolic acidosis resulting in a decrease in base-excess and pH. The concentrations of lactate, pyruvate, potassium, and urea nitrogen and the hemoglobin content were increased by Co2EDTA. The side effects of Co2EDTA in therapeutic doses were more serious than those of DMAP. Thus the latter is superior in the therapy of cyanide poisoning, all the more since it detoxifies more cyanide.