CALCIUM CHANNEL BLOCKER OVERDOSE: TREATMENT WITHIN THE PAST 10 YEARS

Antidotes for cardiovascular drug poisoningNew York UniversityDepartment of Emergency Medicine/Medical ToxicologyDavid H. JangAssistant ProfessorMasters of Science Degree in Clinical Investigation (K30)Clinical and Translational Science Institute (CTSI)

*Funded by the American Academy of Clinical Toxicology Junior InvestigatorResearch Grant and also supported in part by grant 1UL1RR029893 from the National Center for Research Resources, National Institutes of Health.

We used the 50% for the dog protocol. We dec map to 50% at a high infusion then changed to a lower infusion to maintain toxicity. For the rats we have been using a constant infusion of either verapamil or nifedipine. For the amlodipine we will be using a constant infusion until our surrogate marker for death (10% of initial baseline map or in other words 90% decrease from initial map)

The 50% increase in survival time is because we are continuing the infusion until the rats all reach out surrogate for death or the end of our observation period (I think it's 3 hr after start of amlodipine) I don't think there will be many survivors is why we chose the 50% increase in survival time.Kaplan Meier curves will show both - survivors and how long.

1Case 44 year-old man presents with a overdose after an argument with his mother

Patient obtained these medications from his mother who he still lives with in her basement

CaseVitals on presentation:

Blood pressure: 140/90 mmHGHeart rate: 90 BPMRespiratory rate: 12Temperature: 98.6Oxygen saturation: 100% RA

Case6 hours later

CaseRepeat Vitals:

Blood pressure: 85/40 mmHGHeart rate: 40 BPMRespiratory rate: 20Temperature: 98.6Oxygen saturation: 100% RA

CaseIntubated

Hemodynamic supportOn norepinephrineOn dopamineOn epinephrine

Still hypotensive

Options?

Antidotes for cardiovascular drug poisoning

Cardiovascular drug classAntihypertensivesImidazolinesBeta-blockersCalcium channel blockersACE-Is and ARBs

Cardioactive steroidsDigoxin

AntidysrhythmicsFlecainide

Cardiovascular drug classAntihypertensivesImidazolinesBeta-blockersCalcium channel blockersACE-Is and ARBs

Cardioactive steroidsDigoxin

AntidysrhythmicsFlecainide

Not all things are created equal

Beta-blockersNon-selectiveCarvedilol

B1-selectiveAtenololEsmolol

Intrinsic sympathomimeticPindolol

Beta-blockersPotassium channel blockersSotalol

Membrane-stabilizingPropanolol

Calcium channel blockersPhenylalkylamineVerapamil

BenzothiazepineDiltiazem

DihydropyridinesNifedipineAmlodipineNicardipine

Epidemiology

Epidemiology

Epidemiology

Epidemiology

Beta and calcium channel blocker poisoningClinical FeaturesBradycardiaHypotension

ManagementIsotonic fluidsGlucagonInotropes/PressorsHigh-insulinLipid emulsion

Stress no universal effective antidote with severe toxicity.20Beta and calcium channel blocker poisoningClinical FeaturesBradycardiaHypotension

ManagementIsotonic fluidsGlucagonInotropes/PressorsHigh-insulinLipid emulsion

Stress no universal effective antidote with severe toxicity.21Beta and calcium channel blocker poisoningClinical FeaturesBradycardiaHypotension

ManagementIsotonic fluidsGlucagonInotropes/PressorsHigh-insulinLipid emulsion

Stress no universal effective antidote with severe toxicity.22High insulin-euglycemic therapy (HIE)

Historical useGlucose-insulin-potassium (GIK)

Acute myocardial infarction

Heart failure

Myocardium

BackgroundHallmark of BB and CCB poisoning

Bradycardia

Vasodilation

Decreased contractility

BackgroundAltered myocardial physiology

Hyperglycemia (pancreas/liver)

Altered myocardial substrate use

Inhibition of lactate oxidation

Mechanism of actionAlters ions homeostasis (potassium/calcium/sodium)

Metabolic support

Increase lactate uptakeEpi and glucagon promote FFA use (increase energy)

-adrenergic antagonism by propranolol, insulin increased myocardial glucose uptake with subsequent increased contractility.35 In a model of verapamil toxicity, insulin increased glucose uptake with resultant improved contractility.19 Insulin therapy also increased lactate uptake, most likely by restoring pyruvate dehydrogenase activity.21 In this way, lactate serves as an energy source following conversion to pyruvate and then acetyl-CoA that can then enter the Krebs cycle. Insulin-mediated improved contractility appears to be a critical factor to survival from hypodynamic shock. In models of BAA and CCB toxicity, survival is directly due to improved contractility, as insulin neither affected drug-induced hypotension nor bradycardia.19,23 In studies comparing insulin to more traditional therapies for drug-induced cardiogenic shock such as epinephrine and glucagon, insulin improved cardiac function and work efficiency.21 Epinephrine and glucagon did not perform as well because they promoted free fatty acid utilization. As such, epinephrine and glucagon afforded limited increases in contractility at the expense of less efficient work due to increased oxygen demand.

27Experimental evidence

therapy for drug-induced shock was first reported in 1999.39 This case series included four patients who overdosed on verapamil and one with combined amlodipine-atenolol overdose. All failed traditional antidote therapy, but responded to rescue insulin therapy. Since the initial case series, the authors institution has treated six additional patients with rescue insulin therapy following inadequate response to standard antidotes, five of the six with good outcome. Sixty-seven cases appear in the literature that were treated at other institutions.2,3,5,10-13,16, 25-29,31,33,34,36-38 Thus, there is an aggregate of 78 cases in which insulin was used. Of these cases, 72 primarily involved CCBs, five combined CCBs-BAAs, and one BAA. Various regimens of standard antidotes were used prior to insulin therapy and no case received insulin alone. Although no direct outcome comparisons can be made between insulin and standard therapies in these 78 cases, overall survival was 88% when insulin was included in resuscitation. Further review of these cases yields important clinical information that can be used to guide insulin therapy. Experimental models suggest that large doses of insulin (2.5 to 10 units of regular insulin/kg/h) may be necessary to provide inotropic support.1,18,21,23 However, humans appear to respond to less insulin. The most common doses given were 0.5 (n = 31) and 1.0 Units/kg/h (n = 19) of regular insulin in 62 patients where dose was reported. A few patients were treated with higher rates of infusion, up to 2.6 Units/kg/h in one case.36 Sixteen patients received an insulin bolus (10 to 100 Units) prior to continuous infusion. The theoretical advantage to giving an initial insulin bolus is to rapidly saturate insulin receptors to enhance the physiological response. Interestingly, one report noted that patients receiving an insulin bolus prior to the infusion showed a better blood pressure response than patients who received only a continuous infusion.10 Three patients received bolus insulin without continuous infusion, including a patient who inadvertently received 1000 units.34 In this case, hemodynamics improved and there was no adverse event related to the extreme insulin dose. The mean duration of insulin infusion in 24 patients was 33 hours with a range of 0.75 to 96 hours. The need for prolonged infusion likely reflects the prolonged effects and kinetics of cardiovascular drugs typically observed following overdose. The predominant clinical effect of insulin was increased contractility with subsequent blood pressure improvement. Contractility typically increased within 15 to 60 minutes after initiating insulin and often allowed a decrease in concurrent vasopressor requirements. The timing of increased contractility is consistent with the observed response times in animal models.18,23 Other salutary effects were observed during insulin therapy. In two cases, blood pressure increased directly because of increased vascular resistance rather than increased cardiac function.28,37 Two patients converted from third-degree heart block to normal sinus rhythm with increased pulse in temporal relationship to insulin.40 Except for these two patients, insulin therapy did not significantly affect heart rate in other reports. In four cases, authors reported a lack of response to insulin. Reasons for no response in three of these reports may include inadequate dose and excessive delay to insulin therapy.5

28Experimental evidenceGroups

1. Control: (0/6)

2. Epi: (4/6)(2/4)

3. HIE: (6/6)(6/6)

4. Glucagon: (3/6)(0/3)

therapy for drug-induced shock was first reported in 1999.39 This case series included four patients who overdosed on verapamil and one with combined amlodipine-atenolol overdose. All failed traditional antidote therapy, but responded to rescue insulin therapy. Since the initial case series, the authors institution has treated six additional patients with rescue insulin therapy following inadequate response to standard antidotes, five of the six with good outcome. Sixty-seven cases appear in the literature that were treated at other institutions.2,3,5,10-13,16, 25-29,31,33,34,36-38 Thus, there is an aggregate of 78 cases in which insulin was used. Of these cases, 72 primarily involved CCBs, five combined CCBs-BAAs, and one BAA. Various regimens of standard antidotes were used prior to insulin therapy and no case received insulin alone. Although no direct outcome comparisons can be made between insulin and standard therapies in these 78 cases, overall survival was 88% when insulin was included in resuscitation. Further review of these cases yields important clinical information that can be used to guide insulin therapy. Experimental models suggest that large doses of insulin (2.5 to 10 units of regular insulin/kg/h) may be necessary to provide inotropic support.1,18,21,23 However, humans appear to respond to less insulin. The most common doses given were 0.5 (n = 31) and 1.0 Units/kg/h (n = 19) of regular insulin in 62 patients where dose was reported. A few patients were treated with higher rates of infusion, up to 2.6 Units/kg/h in one case.36 Sixteen patients received an insulin bolus (10 to 100 Units) prior to continuous infusion. The theoretical advantage to giving an initial insulin bolus is to rapidly saturate insulin receptors to enhance the physiological response. Interestingly, one report noted that patients receiving an insulin bolus prior to the infusion showed a better blood pressure response than patients who received only a continuous infusion.10 Three patients received bolus insulin without continuous infusion, including a patient who inadvertently received 1000 units.34 In this case, hemodynamics improved and there was no adverse event related to the extreme insulin dose. The mean duration of insulin infusion in 24 patients was 33 hours with a range of 0.75 to 96 hours. The need for prolonged infusion likely reflects the prolonged effects and kinetics of cardiovascular drugs typically observed following overdose. The predominant clinical effect of insulin was increased contractility with subsequent blood pressure improvement. Contractility typically increased within 15 to 60 minutes after initiating insulin and often allowed a decrease in concurrent vasopressor requirements. The timing of increased contractility is consistent with the observed response times in animal models.18,23 Other salutary effects were observed during insulin therapy. In two cases, blood pressure increased directly because of increased vascular resistance rather than increased cardiac function.28,37 Two patients converted from third-degree heart block to normal sinus rhythm with increased pulse in temporal relationship to insulin.40 Except for these two patients, insulin therapy did not significantly affect heart rate in other reports. In four cases, authors reported a lack of response to insulin. Reasons for no response in three of these reports may include inadequate dose and excessive delay to insulin therapy.5

29Experimental evidenceGroups

1. Control: (0/6)

2. Epi: (4/6)(2/4)

3. HIE: (6/6)(6/6)

4. Glucagon: (3/6)(0/3)

therapy for drug-induced shock was first reported in 1999.39 This case series included four patients who overdosed on verapamil and one with combined amlodipine-atenolol overdose. All failed traditional antidote therapy, but responded to rescue insulin therapy. Since the initial case series, the authors institution has treated six additional patients with rescue insulin therapy following inadequate response to standard antidotes, five of the six with good outcome. Sixty-seven cases appear in the literature that were treated at other institutions.2,3,5,10-13,16, 25-29,31,33,34,36-38 Thus, there is an aggregate of 78 cases in which insulin was used. Of these cases, 72 primarily involved CCBs, five combined CCBs-BAAs, and one BAA. Various regimens of standard antidotes were used prior to insulin therapy and no case received insulin alone. Although no direct outcome comparisons can be made between insulin and standard therapies in these 78 cases, overall survival was 88% when insulin was included in resuscitation. Further review of these cases yields important clinical information that can be used to guide insulin therapy. Experimental models suggest that large doses of insulin (2.5 to 10 units of regular insulin/kg/h) may be necessary to provide inotropic support.1,18,21,23 However, humans appear to respond to less insulin. The most common doses given were 0.5 (n = 31) and 1.0 Units/kg/h (n = 19) of regular insulin in 62 patients where dose was reported. A few patients were treated with higher rates of infusion, up to 2.6 Units/kg/h in one case.36 Sixteen patients received an insulin bolus (10 to 100 Units) prior to continuous infusion. The theoretical advantage to giving an initial insulin bolus is to rapidly saturate insulin receptors to enhance the physiological response. Interestingly, one report noted that patients receiving an insulin bolus prior to the infusion showed a better blood pressure response than patients who received only a continuous infusion.10 Three patients received bolus insulin without continuous infusion, including a patient who inadvertently received 1000 units.34 In this case, hemodynamics improved and there was no adverse event related to the extreme insulin dose. The mean duration of insulin infusion in 24 patients was 33 hours with a range of 0.75 to 96 hours. The need for prolonged infusion likely reflects the prolonged effects and kinetics of cardiovascular drugs typically observed following overdose. The predominant clinical effect of insulin was increased contractility with subsequent blood pressure improvement. Contractility typically increased within 15 to 60 minutes after initiating insulin and often allowed a decrease in concurrent vasopressor requirements. The timing of increased contractility is consistent with the observed response times in animal models.18,23 Other salutary effects were observed during insulin therapy. In two cases, blood pressure increased directly because of increased vascular resistance rather than increased cardiac function.28,37 Two patients converted from third-degree heart block to normal sinus rhythm with increased pulse in temporal relationship to insulin.40 Except for these two patients, insulin therapy did not significantly affect heart rate in other reports. In four cases, authors reported a lack of response to insulin. Reasons for no response in three of these reports may include inadequate dose and excessive delay to insulin therapy.5

30Clinical experience

therapy for drug-induced shock was first reported in 1999.39 This case series included four patients who overdosed on verapamil and one with combined amlodipine-atenolol overdose. All failed traditional antidote therapy, but responded to rescue insulin therapy. Since the initial case series, the authors institution has treated six additional patients with rescue insulin therapy following inadequate response to standard antidotes, five of the six with good outcome. Sixty-seven cases appear in the literature that were treated at other institutions.2,3,5,10-13,16, 25-29,31,33,34,36-38 Thus, there is an aggregate of 78 cases in which insulin was used. Of these cases, 72 primarily involved CCBs, five combined CCBs-BAAs, and one BAA. Various regimens of standard antidotes were used prior to insulin therapy and no case received insulin alone. Although no direct outcome comparisons can be made between insulin and standard therapies in these 78 cases, overall survival was 88% when insulin was included in resuscitation. Further review of these cases yields important clinical information that can be used to guide insulin therapy. Experimental models suggest that large doses of insulin (2.5 to 10 units of regular insulin/kg/h) may be necessary to provide inotropic support.1,18,21,23 However, humans appear to respond to less insulin. The most common doses given were 0.5 (n = 31) and 1.0 Units/kg/h (n = 19) of regular insulin in 62 patients where dose was reported. A few patients were treated with higher rates of infusion, up to 2.6 Units/kg/h in one case.36 Sixteen patients received an insulin bolus (10 to 100 Units) prior to continuous infusion. The theoretical advantage to giving an initial insulin bolus is to rapidly saturate insulin receptors to enhance the physiological response. Interestingly, one report noted that patients receiving an insulin bolus prior to the infusion showed a better blood pressure response than patients who received only a continuous infusion.10 Three patients received bolus insulin without continuous infusion, including a patient who inadvertently received 1000 units.34 In this case, hemodynamics improved and there was no adverse event related to the extreme insulin dose. The mean duration of insulin infusion in 24 patients was 33 hours with a range of 0.75 to 96 hours. The need for prolonged infusion likely reflects the prolonged effects and kinetics of cardiovascular drugs typically observed following overdose. The predominant clinical effect of insulin was increased contractility with subsequent blood pressure improvement. Contractility typically increased within 15 to 60 minutes after initiating insulin and often allowed a decrease in concurrent vasopressor requirements. The timing of increased contractility is consistent with the observed response times in animal models.18,23 Other salutary effects were observed during insulin therapy. In two cases, blood pressure increased directly because of increased vascular resistance rather than increased cardiac function.28,37 Two patients converted from third-degree heart block to normal sinus rhythm with increased pulse in temporal relationship to insulin.40 Except for these two patients, insulin therapy did not significantly affect heart rate in other reports. In four cases, authors reported a lack of response to insulin. Reasons for no response in three of these reports may include inadequate dose and excessive delay to insulin therapy.5

31Clinical experience

therapy for drug-induced shock was first reported in 1999.39 This case series included four patients who overdosed on verapamil and one with combined amlodipine-atenolol overdose. All failed traditional antidote therapy, but responded to rescue insulin therapy. Since the initial case series, the authors institution has treated six additional patients with rescue insulin therapy following inadequate response to standard antidotes, five of the six with good outcome. Sixty-seven cases appear in the literature that were treated at other institutions.2,3,5,10-13,16, 25-29,31,33,34,36-38 Thus, there is an aggregate of 78 cases in which insulin was used. Of these cases, 72 primarily involved CCBs, five combined CCBs-BAAs, and one BAA. Various regimens of standard antidotes were used prior to insulin therapy and no case received insulin alone. Although no direct outcome comparisons can be made between insulin and standard therapies in these 78 cases, overall survival was 88% when insulin was included in resuscitation. Further review of these cases yields important clinical information that can be used to guide insulin therapy. Experimental models suggest that large doses of insulin (2.5 to 10 units of regular insulin/kg/h) may be necessary to provide inotropic support.1,18,21,23 However, humans appear to respond to less insulin. The most common doses given were 0.5 (n = 31) and 1.0 Units/kg/h (n = 19) of regular insulin in 62 patients where dose was reported. A few patients were treated with higher rates of infusion, up to 2.6 Units/kg/h in one case.36 Sixteen patients received an insulin bolus (10 to 100 Units) prior to continuous infusion. The theoretical advantage to giving an initial insulin bolus is to rapidly saturate insulin receptors to enhance the physiological response. Interestingly, one report noted that patients receiving an insulin bolus prior to the infusion showed a better blood pressure response than patients who received only a continuous infusion.10 Three patients received bolus insulin without continuous infusion, including a patient who inadvertently received 1000 units.34 In this case, hemodynamics improved and there was no adverse event related to the extreme insulin dose. The mean duration of insulin infusion in 24 patients was 33 hours with a range of 0.75 to 96 hours. The need for prolonged infusion likely reflects the prolonged effects and kinetics of cardiovascular drugs typically observed following overdose. The predominant clinical effect of insulin was increased contractility with subsequent blood pressure improvement. Contractility typically increased within 15 to 60 minutes after initiating insulin and often allowed a decrease in concurrent vasopressor requirements. The timing of increased contractility is consistent with the observed response times in animal models.18,23 Other salutary effects were observed during insulin therapy. In two cases, blood pressure increased directly because of increased vascular resistance rather than increased cardiac function.28,37 Two patients converted from third-degree heart block to normal sinus rhythm with increased pulse in temporal relationship to insulin.40 Except for these two patients, insulin therapy did not significantly affect heart rate in other reports. In four cases, authors reported a lack of response to insulin. Reasons for no response in three of these reports may include inadequate dose and excessive delay to insulin therapy.5

32Adverse eventsHypoglycemia

Hypokalemia

Treatment guidelines

Intralipid

BackgroundTriglycerides and phospholipidsPrimary triglycerides composed of linoleic, linolenic, and stearic acidpH 8, isotonic, various concentrations availiable (20% is primarily used)

fat emulsion (IFE) has been used as a source of parenteral nutrition for over 40 years. More recently, IFE has also been used as a diluent for intravenous drug delivery of highly lipophilic xenobiotics such as propofol and liposomal amphotericin. The use of IFE as an antidote is most extensively studied for the treatment of local anesthetic toxicity, specifically from bupivacaine, but new applications that are being investigated and reported on include the treatment of overdose from lipophilic drugs such as calcium channel blockers, cyclic antidepressants, clomipramine, and beta adrenergic antagonists, to name a few.

Nelson, Lewis S.; Lewin, Neal A.; Howland, Mary Ann; Hoffman, Robert S.; Goldfrank, Lewis R.; Flomenbaum, Neal E. (2010-07-16). Goldfrank's Toxicologic Emergencies, Ninth Edition (Goldfrank's Toxicologic Emergenciess)) (Kindle Locations 52055-52059). McGraw-Hill Professional. Kindle Edition. 36Mechanism of action1. Modulation of intracellular metabolism

2. Lipid sink

3. Activation of ion channels

MECHANISM OF ACTION The mechanisms of action of IFE in toxicology are not clearly understood. There are currently three proposed mechanisms of action of IFE in toxicology: modulation of intracellular metabolism, a lipid sink or sponge mechanism, and activation of ion channels. In experimental models of poisoning from xenobiotics that alter intracellular energy metabolism, toxicity was successfully treated with IFE, suggesting that repairing or circumventing this dysfunction may be involved. Bupivacaine blocks carnitine-dependent mitochondrial lipid transport and inhibits adenosine triphosphatase (ATPase) synthetase in the electron transport chain.6,51 Verapamil also inhibits intracellular processing of fatty acids,20,21 but it inhibits insulin release and produces insulin resistance as well.21 The cyclic antidepressant amitriptyline depresses human myocardial contraction independent of an effect on conduction16 and inhibits medium- and short-chain fatty acid metabolism.48 Propranolol changes intracellular energy from primarily fatty acid to carbohydrate-dependent metabolism.28

37Experimental evidence

Experimental evidence

Clinical experience

therapy for drug-induced shock was first reported in 1999.39 This case series included four patients who overdosed on verapamil and one with combined amlodipine-atenolol overdose. All failed traditional antidote therapy, but responded to rescue insulin therapy. Since the initial case series, the authors institution has treated six additional patients with rescue insulin therapy following inadequate response to standard antidotes, five of the six with good outcome. Sixty-seven cases appear in the literature that were treated at other institutions.2,3,5,10-13,16, 25-29,31,33,34,36-38 Thus, there is an aggregate of 78 cases in which insulin was used. Of these cases, 72 primarily involved CCBs, five combined CCBs-BAAs, and one BAA. Various regimens of standard antidotes were used prior to insulin therapy and no case received insulin alone. Although no direct outcome comparisons can be made between insulin and standard therapies in these 78 cases, overall survival was 88% when insulin was included in resuscitation. Further review of these cases yields important clinical information that can be used to guide insulin therapy. Experimental models suggest that large doses of insulin (2.5 to 10 units of regular insulin/kg/h) may be necessary to provide inotropic support.1,18,21,23 However, humans appear to respond to less insulin. The most common doses given were 0.5 (n = 31) and 1.0 Units/kg/h (n = 19) of regular insulin in 62 patients where dose was reported. A few patients were treated with higher rates of infusion, up to 2.6 Units/kg/h in one case.36 Sixteen patients received an insulin bolus (10 to 100 Units) prior to continuous infusion. The theoretical advantage to giving an initial insulin bolus is to rapidly saturate insulin receptors to enhance the physiological response. Interestingly, one report noted that patients receiving an insulin bolus prior to the infusion showed a better blood pressure response than patients who received only a continuous infusion.10 Three patients received bolus insulin without continuous infusion, including a patient who inadvertently received 1000 units.34 In this case, hemodynamics improved and there was no adverse event related to the extreme insulin dose. The mean duration of insulin infusion in 24 patients was 33 hours with a range of 0.75 to 96 hours. The need for prolonged infusion likely reflects the prolonged effects and kinetics of cardiovascular drugs typically observed following overdose. The predominant clinical effect of insulin was increased contractility with subsequent blood pressure improvement. Contractility typically increased within 15 to 60 minutes after initiating insulin and often allowed a decrease in concurrent vasopressor requirements. The timing of increased contractility is consistent with the observed response times in animal models.18,23 Other salutary effects were observed during insulin therapy. In two cases, blood pressure increased directly because of increased vascular resistance rather than increased cardiac function.28,37 Two patients converted from third-degree heart block to normal sinus rhythm with increased pulse in temporal relationship to insulin.40 Except for these two patients, insulin therapy did not significantly affect heart rate in other reports. In four cases, authors reported a lack of response to insulin. Reasons for no response in three of these reports may include inadequate dose and excessive delay to insulin therapy.5

40Adverse events

Adverse events

Treatment guidelines

www.lipidrescue.org

43Treatment guidelines

SummaryConsider HIE early for suspected CCB poisoning

Consider lipid emulsion when a patient is perimortem with suspected lipid-soluble medication

Methylene blue (MB)

Methylene blue Sentinel node detection

Acquired methemoglobinemia

Vasodilatory shockAnaphylaxisSepsis

Now we know a little more about NO, what does methylene blue have to do with NO?47

Nitric oxide synthase

Physiology of vascular tone

What is nitric oxide (NO)?NO-cGMP pathwayRole of nitric oxide in vasodilatory shock SepsisAnaphylaxisTreatment NOS analogues Ng monomethyl-L-arginine (L-NMMA)

49The evidence for MB

Mechanism of action

Vasodilatory shock from overdose?

52Why calcium channel blockers?

Why calcium channel blockers?

WHY DO WE EVEN CARE ABOUT NITRIC OXIDE?54

Mechanism of action

So to test this

56MethodsDesign:Controlled, blinded animal designSubjects:Adult Sprague-Dawley rats (300-600 grams)Preparation (Instrumentation/sedation)Protocol:Phase 1: Dose-findingPhase 2: Methylene blue

Our study design will incorporate two phases. The first phase will be an amlodipine toxicity dose determination. We will start with a dose of 4 mg/kg of amlodipine as a bolus. This dose was chosen based on an experiment which studied the effects of intravenous amlodipine on blood pressure in a dose-dependent fashion in a rat model. 16 We plan to incrementally increase the dose by 50% (6 and 8 mg/kg) and to decrease the dose by 50% (2 and 1 mg/kg). We expect 5 rats at each dose will allow us to determine the desired amlodipine toxicity dose. In order to determine the minimal toxic dose of amlodipine (without methylene blue therapy) that produces a decrease in mean arterial blood pressure to 10% of baseline (our surrogate marker for death) by 60 minutes after administration. We are requesting 25 rats (5 rats per group for each amlodopine dose 1, 2, 4, 6, 8 mg/kg). The second phase will incorporate the treatment phase. We will be performing a controlled, blinded laboratory investigation using 11 adult Sprague-Dawley rats (300-600 grams) in each treatment arm. Amlodipine will be given as explained above and in the dose determined above. Five minutes after the amlodipine bolus, the rats will receive intravenous methylene blue (2 mg/kg bolus) or an equivalent amount normal saline. There will be 2 groups (n= 11 per group): Amlodipine/methylene blue or amlodipine/normal saline. The animals will be observed for a total of 3 hours after the start of the amlodipine/methylene blue. The primary endpoint will be an improvement of 50% of the survival time. One goal of the proposed study is to test the null hypothesis that the population means are equal. The criterion for significance (alpha) has been set at 0.05. The test is 2-tailed, which means that an effect in either direction will be interpreted. The goal of the study is to determine the effectiveness of methylene in the treatment of amlodipipne toxicity. We will use mean arterial blood pressure (MAP) as a measure of hemodynamic parameters. A sample size calculation indicates that we will need 11 rats per group to detect an increase of 50% of the survival time with statistical certainty. We plan to request a total of 55 animals for the protocol 25 to determine the dosing, 11 for each arm (total of 2 arms) and 8 extra for any unforeseen complications such as potential errors and unexpected deaths.

57Protocol summary and timelinePhase 1: Amlodipine dose determination4 mg/kg: Incrementally increase dose 50% and decrease 50%(5 rats per group 1, 2, 4, 6, 8 mg/kg)End-point: Decrease of mean arterial pressure to10% of baseline

16 We plan to incrementally increase the dose by 50% (6 and 8 mg/kg) and to decrease the dose by 50% (2 and 1 mg/kg). We expect 5 rats at each dose will allow us to determine the desired amlodipine toxicity dose. In order to determine the minimal toxic dose of amlodipine (without methylene blue therapy) that produces a decrease in mean arterial blood pressure to 10% of baseline (our surrogate marker for death) by 60 minutes after administration. We are requesting 25 rats (5 rats per group for each amlodipine dose 1, 2, 4, 6, 8 mg/kg). 58Amlodipine dose

16 We plan to incrementally increase the dose by 50% (6 and 8 mg/kg) and to decrease the dose by 50% (2 and 1 mg/kg). We expect 5 rats at each dose will allow us to determine the desired amlodipine toxicity dose. In order to determine the minimal toxic dose of amlodipine (without methylene blue therapy) that produces a decrease in mean arterial blood pressure to 10% of baseline (our surrogate marker for death) by 60 minutes after administration. We are requesting 25 rats (5 rats per group for each amlodipine dose 1, 2, 4, 6, 8 mg/kg). 59Protocol summary and timelineGroup 1: AmlodipineNormal saline (Control group)Group 2: AmlodipineMethylene Blue (Treatment group)

16 We plan to incrementally increase the dose by 50% (6 and 8 mg/kg) and to decrease the dose by 50% (2 and 1 mg/kg). We expect 5 rats at each dose will allow us to determine the desired amlodipine toxicity dose. In order to determine the minimal toxic dose of amlodipine (without methylene blue therapy) that produces a decrease in mean arterial blood pressure to 10% of baseline (our surrogate marker for death) by 60 minutes after administration. We are requesting 25 rats (5 rats per group for each amlodipine dose 1, 2, 4, 6, 8 mg/kg). 60Protocol summary and timelineBaselineAmlodipineMB (2 mg/kg)or saline0 mins180 minsPhase 2: Methylene blue treatment15 min5 min3-hours or until deathGroup 1: AmlodipineNormal saline (Control group)Group 2: AmlodipineMethylene Blue (Treatment group)

16 We plan to incrementally increase the dose by 50% (6 and 8 mg/kg) and to decrease the dose by 50% (2 and 1 mg/kg). We expect 5 rats at each dose will allow us to determine the desired amlodipine toxicity dose. In order to determine the minimal toxic dose of amlodipine (without methylene blue therapy) that produces a decrease in mean arterial blood pressure to 10% of baseline (our surrogate marker for death) by 60 minutes after administration. We are requesting 25 rats (5 rats per group for each amlodipine dose 1, 2, 4, 6, 8 mg/kg). 61Results

Methylene blue-Pending

Normal Saline-Pending

Questions?