Tylenol Toxicity Kelly Kasteel 1 OBJECTIVES Tylenol toxicity

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Tylenol Toxicity Kelly Kasteel 1

Tylenol Toxicity Kelly Kasteel 1

OBJECTIVES • Tylenol toxicity : a) Epidemiology b) Dosing c) Metabolism d) Diagnosis e)

OBJECTIVES • Tylenol toxicity : a) Epidemiology b) Dosing c) Metabolism d) Diagnosis e) Treatment f) Prognosis 2

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Epidemiology ¡ Tylenol- A name by many others ¡ Most popular OTC analgesic in

Epidemiology ¡ Tylenol- A name by many others ¡ Most popular OTC analgesic in North America ¡ Lay people commonly underestimate its toxicity Acephen™ [OTC]; Apra Children's [OTC]; Aspirin Free Anacin® Maximum Strength [OTC]; Cetafen Extra® [OTC]; Cetafen® [OTC]; Comtrex® Sore Throat Maximum Strength [OTC]; Fever. ALL® [OTC]; Genapap™ Children [OTC]; Genapap™ Extra Strength [OTC]; Genapap™ Infant [OTC]; Genapap™ [OTC]; Genebs Extra Strength [OTC]; Genebs [OTC]; Infantaire [OTC]; Mapap Children's [OTC]; Mapap Extra Strength [OTC]; Mapap Infants [OTC]; Mapap [OTC]; Nortemp Children's [OTC]; Pain Eze [OTC]; Silapap® Children's [OTC]; Silapap® Infants [OTC]; Tycolene Maximum Strength [OTC]; Tycolene [OTC]; Tylenol® 8 Hour [OTC]; Tylenol® Arthritis Pain [OTC]; Tylenol® Children's with Flavor Creator [OTC]; Tylenol® Children's [OTC]; Tylenol® Extra Strength [OTC]; Tylenol® Infants [OTC]; Tylenol® Junior [OTC]; Tylenol® [OTC]; Valorin Extra [OTC]; Valorin [OTC]. 4

Epidemiology ¡ ¡ ¡ intentional (suicidal)=unintentional (chronic) poisonings Tylenol is often thought to be

Epidemiology ¡ ¡ ¡ intentional (suicidal)=unintentional (chronic) poisonings Tylenol is often thought to be benign, or is a “hidden ingredient” in other remedies. Accounts for more overdoses and overdose deaths each year in North America than any other pharmaceutical agent l In 2000, it accounted for 5% of overdoses and 23% of reported fatalities. 5 5

Dosing ¡ ¡ ¡ “Plain Tylenol”: 1. Regular-strength: 325 mg 2. Extra-strength: 500 mg

Dosing ¡ ¡ ¡ “Plain Tylenol”: 1. Regular-strength: 325 mg 2. Extra-strength: 500 mg Pediatric syrup l 1. 160 mg/5 m. L –Childrens l 2. 80 mg/0. 8 m. L -Infants Other Tylenol formats include: a) tablets b) chew-tabs c) dissolvable d) capsules e) suppositories 6

Dosing ¡ Tylenol is also available as a co-ingredient in several combination medications: 1.

Dosing ¡ Tylenol is also available as a co-ingredient in several combination medications: 1. Tylenol #3 (Tylenol 300 and Codeine 30 mg) 2. Percocet (Tylenol 300 mg and Oxycodone 2. 5/5/7. 5 mg) 7

Dosing ¡ Recommended Tylenol dosing is as follows: l l l Adult: 325 -650

Dosing ¡ Recommended Tylenol dosing is as follows: l l l Adult: 325 -650 mg every 4 -6 hours or 1000 mg 3 -4 times/day; do not exceed 4 g/day. 2. 5 mg in liver failure ( defined as Peds: 10 -15 mg/kg/dose every 4 -6 hours as needed; do not exceed 5 doses (80 mg/kg) in 24 hours 8

Acute Toxic Dosing ¡ The minimum toxic dose for an acute ingestion of Tylenol

Acute Toxic Dosing ¡ The minimum toxic dose for an acute ingestion of Tylenol (ie. occurring within a time frame of four hours) is: a) Adults: 7. 5 g b) Peds: 150 mg/kg It may be prudent to also use these levels as the minimum acute toxic dose per 24 hours. ¡ Ingestions occurring over a period of more than four hours are arbitrarily termed chronic ingestions. ¡ 9

Chronic Toxic Dosing The minimum toxic dose for chronic ingestions of Tylenol is less

Chronic Toxic Dosing The minimum toxic dose for chronic ingestions of Tylenol is less well defined. ¡ Rosen’s suggests: 4 ¡ a) Adults: > 4 g/d if risk factors ** > 7. 5 g/d if no risk factors b) Peds: > 75 mg/kg/d if risk factors > 150 mg/kg/d if no risk factors ¡ ** - Risk factors will be discussed later 10

Metabolism ¡ ¡ Immediate-release Tylenol is rapidly absorbed in the gut, with peak serum

Metabolism ¡ ¡ Immediate-release Tylenol is rapidly absorbed in the gut, with peak serum levels typically achieved in 30 m – 2 hr Peak serum levels can be delayed… 1. 2. 3. With sustained-release formulations. With combination formulations. In overdoses. a) b) peak levels not being achieved for up to 4 hrs following overdoses of immediate-release Tylenol. peaks even >4 hrs following OD’s of extended-release Tylenol. 2 11

Metabolism Okay… time to make learning fun. ¡ Who hasn’t memorized and forgotten the

Metabolism Okay… time to make learning fun. ¡ Who hasn’t memorized and forgotten the pathways of Tylenol metabolism at least five times? ¡ l ¡ Well… here’s number six. Under normal circumstances, Tylenol is metabolized in the following manner: 12

5% Tylenol 20 -45% Sulfation Glucuronidation Oxidation Remaining 5 -15% 40 -65% NAPQI Cyt

5% Tylenol 20 -45% Sulfation Glucuronidation Oxidation Remaining 5 -15% 40 -65% NAPQI Cyt P 450 Tylenol – mercaptate compound Glutathione NORMAL TYLENOL METABOLISM 13

5% Tylenol 20 -45% Sulfation Glucuronidation Oxidation Remaining 5 -15% 40 -65% NAPQI Cyt

5% Tylenol 20 -45% Sulfation Glucuronidation Oxidation Remaining 5 -15% 40 -65% NAPQI Cyt P 450 Tylenol – mercaptate compound Glutathione NORMAL TYLENOL METABOLISM 14

Tylenol SATURATED 5% SATURATED 20 -45% Sulfation SATURATED 40 -65% Glucuronidation Oxidation Remaining >>>

Tylenol SATURATED 5% SATURATED 20 -45% Sulfation SATURATED 40 -65% Glucuronidation Oxidation Remaining >>> 55 --15% NAPQI Cyt P 450 Tylenol mercaptate compound Glutathione TYLENOL METABOLISM IN OVERDOSE 15

Risk Factors for Tylenol Toxicity ¡ An obvious corollary of the previous slide is

Risk Factors for Tylenol Toxicity ¡ An obvious corollary of the previous slide is that anything which potentiates the action of Cyt P 450 will accelerate the production of NAPQI. ¡ (And vice-versa. ) 16

Risk Factors Cyt P 450 Potentiators ( 1. 2. Chronic alcohol consumption Anticonvulsants: l

Risk Factors Cyt P 450 Potentiators ( 1. 2. Chronic alcohol consumption Anticonvulsants: l l l 3. l 5. Tegretol Dilantin Phenobarb Anti-tuberculosis medications: l 4. NAPQI): Rifampin INH Dexamethasone St. John’s Wort 17

(Not) Risk Factors Cyt P 450 Inhibitors ( Acute alcohol consumption Macrolides 1. 2.

(Not) Risk Factors Cyt P 450 Inhibitors ( Acute alcohol consumption Macrolides 1. 2. • 3. 4. 5. 6. 7. NAPQI): Erythromycin, Biaxin, Zithromax Antifungals Amiodarone HIV protease-inhibitors Cyclosporine Grapefruit juice 18

Quick note on the sauce… ¡ ¡ As you can see, if you are

Quick note on the sauce… ¡ ¡ As you can see, if you are going to overdose on Tylenol, at least have the good sense to wash it down with some Scotch. Chronic Et. OH use, on the other hand, will (at least, theoretically) increase the risk of sequelae in Tylenol OD: 1. 2. Cyt P 450 is potentiated. Alcoholics tend to have low of glutathione. pre-existing levels 19

Quick note on the sauce… In practice, alcoholics tend not to be at increased

Quick note on the sauce… In practice, alcoholics tend not to be at increased risk for hepatotoxicity following an acute overdose of Tylenol. Practice matches theory more closely, however, in alcoholics with chronic Tylenol overdoses. ¡ ¡ l Even so, these pts are still unlikely to develop toxicity if they restrict their Tylenol use to <4 g/d. 20 *

More Risk Factors ¡ Anything that slows down or interferes with sulfation and/or glucouronidation

More Risk Factors ¡ Anything that slows down or interferes with sulfation and/or glucouronidation will leave more Tylenol available for Cyt P 450 processing (and NAPQI production). 1. 2. 3. Septra and AZT are metabolized via glucouronidation (and may slow this pathway down for Tylenol). Patients with Gilbert’s disease may have decreased glucouronidation. Elderly patients may have decreased rates of sulfation and/or glucouronidation. 21

More Risk Factors ¡ Anything that decreases the amount of glutathione in the body

More Risk Factors ¡ Anything that decreases the amount of glutathione in the body leaves less of it available to bind to NAPQI. 1. Chronically malnourished or acutely fasting patients may have decreased glutathione stores. l 2. Febrile pediatric patients are especially susceptible to falling into the latter group. Elderly patients can have chronically decreased glutathione stores. 22

Summary of Risk Factors 1. 2. 3. 4. 5. 6. 7. Induced Cyt-P 450

Summary of Risk Factors 1. 2. 3. 4. 5. 6. 7. Induced Cyt-P 450 Chronic alcoholism Acute fasting (may include febrile peds) Chronic malnutrition Septra or AZT use Gilbert’s disease Elderly patients 23

Pictorial Summary of Risk Factors 1. Elderly patient. 2. Fallen off wagon. 3. On

Pictorial Summary of Risk Factors 1. Elderly patient. 2. Fallen off wagon. 3. On INH for TB. 4. On Septra for bladder infection. 5. Septra is making her vomit… so she’s not eating. 6. Gilbert’s disease. 24

Treatment ¡ (For reasons that I hope will later become obvious), I will now

Treatment ¡ (For reasons that I hope will later become obvious), I will now break with tradition and discuss treatment before diagnosis. 25

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity:

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity: 1. Stage One (0 -24 hrs) • minimal clinical findings. • may be completely asymptomatic. • may have minor non-specific findings such as N/V, pallor, malaise. • liver panel unremarkable. 26

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity:

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity: 2. Stage Two (Day 2 -3) • clinical signs of hepatotoxicity. Most • RUQ pain, hepatomegaly, sensitive AST/ALT/bili/PT/lipase elevation. • patients may also develop early signs of renal failure or pancreatitis during this stage. 27

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity:

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity: 2. Stage Two continued… • From Stage 2, patients progress either to Stage 4 (with subsequent full recovery) or to Stage 3 (with subsequent probable death). 28

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity:

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity: 3. Stage Three (Day 3 -4) • Fulminant hepatic failure +/- death • Associated lactic acidosis, coagulopathy, encephalopathy; possible pancreatitis, hypoglycemia, ARF. • Marked elevation of liver enzymes (with AST typically >3, 000), • Elevation of NH 3, coags, lactate. 29

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity:

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity: 3. Stage Three continued… • Stage 3 will progress to: (a)death. (b)if lucky, a liver transplant. (c) if even luckier, Stage 4 and a full recovery. 30

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity:

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity: 4. Stage Four (Day 4 - 10) • If you do not die in Stage 3, you arrive at Stage 4 with rapid and complete hepatic recovery. • Clinical recovery usually begins by Day 4 and is complete by Day 7 -10. • Histological recovery may take up to 3 months. 31

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity:

Clinical Stages • In untreated patients, there are four clinical stages of Tylenol toxicity: • Summary of stages: Days: 1. Minimal symptoms 1 2. Moderate symptoms 2 -3 3. Severe symptoms +/- death 3 -4 4. Complete recovery 4 -10 32

Treatment ¡ ¡ The treatment for Tylenol toxicity is Nacetylcysteine, or NAC. Early on

Treatment ¡ ¡ The treatment for Tylenol toxicity is Nacetylcysteine, or NAC. Early on in Tylenol toxicity, NAC: 1. 2. 3. Acts as a glutathione precursor, increasing glutathione stores. Binds NAPQI directly. Enhances the sulfation pathway. 33

Treatment ¡ Later on in Tylenol toxicity… (when Tylenol levels are absent, but hepatotoxicity

Treatment ¡ Later on in Tylenol toxicity… (when Tylenol levels are absent, but hepatotoxicity has begun) …NAC continues to offer benefit: 1. 2. 3. 4. 5. It has strong antiinflammatory effects. It has strong antioxidant effects. It scavenges free radicals. It modifies cytokine production. It increases inotropy and vasodilation, thereby improving microcirculation. 34

Treatment ¡ ¡ ¡ So how well does NAC work? Pretty bloody well. If

Treatment ¡ ¡ ¡ So how well does NAC work? Pretty bloody well. If NAC is initiated within 8 hours of (even a massive) acute Tylenol overdose, the patient: 1. 2. ¡ Is very unlikely to suffer (even transient) serious hepatotoxicity. Essentially never dies from the overdose Beyond the 8 -hour point, NAC’s protective abilities steadily diminish. 35

Treatment But NAC continues to provide significant benefit even if initiated quite late in

Treatment But NAC continues to provide significant benefit even if initiated quite late in Tylenol toxicity: ¡ l l In a 1991 trial in the BMJ, 50 patients presenting with Tylenol-induced fulminant liver failure were randomized to either: (a) NAC (b) Supportive care NAC patients had significantly less: 1. 2. 3. mortality (20% vs. 48%) cerebral edema (40% vs. 68%) need for inotropes (48% vs. 80%) 36

Diagnosis 37

Diagnosis 37

Diagnosis • The diagnosis of a disease (as any medical student will tell you)

Diagnosis • The diagnosis of a disease (as any medical student will tell you) begins with history. • Sadly, with Tylenol toxicity, history can sometimes be a bit of a problem. 38

Diagnosis ¡ Patients coming to the ED with a Tylenol overdose are not, strictly

Diagnosis ¡ Patients coming to the ED with a Tylenol overdose are not, strictly speaking, the most reliable of historians. • So you really have to rely on something else. 39

Diagnosis ¡ As such, the diagnosis of Tylenol toxicity rests on: 1. 2. 3.

Diagnosis ¡ As such, the diagnosis of Tylenol toxicity rests on: 1. 2. 3. ¡ Tylenol levels AST/ALT (and other bloodwork) levels The Rumack-Matthew nomogram. The “other bloodwork” to consider drawing in Tylenol toxicity includes: 1. 2. PT, BUN/Cr, glucose, lipase, CK Medication levels (eg. ASA, Et. OH, etc. ) 40

Cost of Diagnosis ¡ ¡ In a 1989 study in the Annals of Emergency

Cost of Diagnosis ¡ ¡ In a 1989 study in the Annals of Emergency Medicine, 1 in 500 patients who presented to the ED with an overdose—but denied Tylenol ingestion—was found to have a potentially toxic level. 5 Tintinalli estimates that the cost of drawing 500 negative Tylenol levels is less than the cost of missing one case of Tylenol-induced hepatic failure. 5 41

Rumack. Matthew Nomogram • This is the Cdn units (umol/L) version of the Rumack-Matthew

Rumack. Matthew Nomogram • This is the Cdn units (umol/L) version of the Rumack-Matthew nomogram. • Therapeutic Tylenol levels are 70 -130 umol/L. • Note that the y-axis is logarithmic. 42

 • “Tylenol levels” on the y-axis range from 0 – 2000. • “Time

• “Tylenol levels” on the y-axis range from 0 – 2000. • “Time since ingestion” on the x-axis ranges from 0 – 24 hours. • Toxicity cannot be predicted before 4 hrs or after 24 hrs using this nomogram. 43

 • The nomogram is based on a study of a large number of

• The nomogram is based on a study of a large number of patients who following an acute OD of immediaterelease Tylenol were not treated with antidote. 2 • Note that there are two diagonal lines indicating potential toxicity. 44

 • The original nomogram used just one line – the upper line. •

• The original nomogram used just one line – the upper line. • Following an acute ingestion of immediaterelease Tylenol, no patients with a Tylenol level below the upper line… • developed severe hepatotoxicity or died. 45

 • The U. S. FDA later developed a second line—the lower line—to offer

• The U. S. FDA later developed a second line—the lower line—to offer an increased safety margin. • Presumably to cover those patients with risk factors for Tylenol toxicity. 46

 • Americans use the lower line as their indicator to treat. • Canadians

• Americans use the lower line as their indicator to treat. • Canadians (choosing to base their treatment protocols on actual research) use the upper line. 47

 • To use the nomogram… • Wait until at least four hours after

• To use the nomogram… • Wait until at least four hours after ingestion of an acute OD of immediaterelease Tylenol • (This 4 hr waiting period ensures that serum levels have peaked. ) • Then simply draw and plot the Tylenol level. 48

 • N. B. It is safe to wait for 4 hrs before drawing

• N. B. It is safe to wait for 4 hrs before drawing the first Tylenol level. • This is because the risk of Tylenol toxicity (following an acute OD) is essentially zero as long as NAC is initiated within 8 hrs of ingestion. 49

 • Plot points below the upper-line represent: • negligible risk of significant hepatotoxicity

• Plot points below the upper-line represent: • negligible risk of significant hepatotoxicity • essentially no risk of longterm morbidity or mortality. • And, thus, no need for treatment. 50

 • Plot points above the upper-line represent… 1. 60% chance of AST >

• Plot points above the upper-line represent… 1. 60% chance of AST > 1000 2. 1% chance of renal failure 3. 5% chance of mortality • And, thus, the need for treatment. 51

 • So… draw your level, plot your point, start your NAC. • Piece

• So… draw your level, plot your point, start your NAC. • Piece of cake right? • Well… mayhab, mayhab no. 52

Diagnosis There are some potential problems with the Rumack-Matthew nomogram. 1. 2. 3. What

Diagnosis There are some potential problems with the Rumack-Matthew nomogram. 1. 2. 3. What about chronic or multiple ingestions? What if the time of acute ingestion is not firmly established? What if the pt is lying to you? 4. What if the acute ingestion was <4 or >24 hours ago? 5. What about sustained-release Tylenol? 53

Diagnosis What about chronic or multiple ingestions? 1. l It is generally accepted that

Diagnosis What about chronic or multiple ingestions? 1. l It is generally accepted that the nomogram is not reliable in this situation. ¡ Tylenol levels could potentially be therapeutic (or, for that matter, undetectable) even in the face of significant hepatotoxicity. 54

Diagnosis 2. What if the time of acute ingestion is not firmly established? l

Diagnosis 2. What if the time of acute ingestion is not firmly established? l l l In this instance (since the actual time of ingestion may well be >8 hrs ago), one would be wise to draw a Tylenol level at once and initiate NAC immediately. This is especially true for patients who have RUQ pain, are jaundiced, or look ill. When the Tylenol (and other bloodwork) levels come back, one can decide whether or not to continue therapy. 55

Diagnosis 3. What if the pt is lying to you? l If you have

Diagnosis 3. What if the pt is lying to you? l If you have these, then feel free to trust all your patients and follow the nomogram. – If you are not quite as trusting, then draw a Tylenol level at once and initiate NAC immediately. – At least one conscientious, young (and handsome) physician I know recommends trusting no one. 56

Diagnosis 4. What if the ingestion was < 4 or >24 hours ago? l

Diagnosis 4. What if the ingestion was < 4 or >24 hours ago? l As already mentioned, the nomogram is unreliable outside of these timeframes. a) b) If <4 hrs from time of ingestion, Tylenol levels may still be increasing. If >24 hrs from time of ingestion, Tylenol levels may be undetectable, even in the face of significant hepatotoxicity. 57

Diagnosis 5. What about sustained-release Tylenol? l l l There is not currently sufficient

Diagnosis 5. What about sustained-release Tylenol? l l l There is not currently sufficient evidence to validate (or invalidate) the nomogram for use with sustained-release Tylenol. 2 Which is not to say we don’t do use it. In something of an “off-label” use of the nomogram, manufacturers of sustained-release Tylenol recommend… ¡ “draw both a 4 - and 8 -hour Tylenol level, and initiate NAC if either level is potentially toxic. ” 58

And now… a return to Treatment 59

And now… a return to Treatment 59

Treatment ¡ ¡ In the ED, the most difficult question to answer is not

Treatment ¡ ¡ In the ED, the most difficult question to answer is not which therapy to use (psst… use NAC), but whether or not therapy is actually required. And this question will have to be answered at least twice: Once before the bloodwork is back. (b) Once after the bloodwork is back. (a) 60

Treatment ¡ And—both times—one will need to consider whethere is grounds for clinical suspicion

Treatment ¡ And—both times—one will need to consider whethere is grounds for clinical suspicion of Tylenol toxicity: 1. Hx of ingestion suggestive of toxicity. a) acute overdose (eg. >7. 5 g or >150 mg/kg). b) chronic supratherapeutic use (>4 g/d or >75 mg/kg). c) chronic therapeutic use in a patient with risk factors. d) chronic use or overuse of sustained-release or combined-ingredient Tylenol. 61

Treatment ¡ And—both times—one will need to consider whethere is grounds for clinical suspicion

Treatment ¡ And—both times—one will need to consider whethere is grounds for clinical suspicion of Tylenol toxicity: 2. Hx of ingestion that is not suggestive of toxicity, but sounds like it is: a) inconsistent. b) incomplete. c) a big fat lie. 62

Treatment ¡ And—both times—one will need to consider whethere is grounds for clinical suspicion

Treatment ¡ And—both times—one will need to consider whethere is grounds for clinical suspicion of Tylenol toxicity: 3. Clinical findings suspicious of Tylenol toxicity: a) RUQ pain b) jaundice c) N/V d) lethargy and malaise e) dehydration 63

Treatment ¡ In summary, be clinically suspicious of Tylenol toxicity if: 1. 2. 3.

Treatment ¡ In summary, be clinically suspicious of Tylenol toxicity if: 1. 2. 3. History sounds bad. History sounds like bullshit. Clinical findings. 64

Treatment ¡ So back to the original question: l When is therapy warranted? 65

Treatment ¡ So back to the original question: l When is therapy warranted? 65

Treatment before bloodwork ¡ Before bloodwork is back, initiate NAC if: 1. Clinical suspicion

Treatment before bloodwork ¡ Before bloodwork is back, initiate NAC if: 1. Clinical suspicion of Tylenol toxicity. ¡ ¡ ¡ Some will argue that if the bloodwork will be back within 8 hours of the time of ingestion, that you do not need to initiate empiric therapy. And, strictly speaking, this is true. So, by all means… 66

Treatment before bloodwork ¡ …if your patient took an acute dose of immediate-release Tylenol

Treatment before bloodwork ¡ …if your patient took an acute dose of immediate-release Tylenol at an exact and known time, has no risk factors, and is not potentially lying to you, then go ahead and wait for the bloodwork to come back. 67 #

Treatment after bloodwork ¡ After bloodwork is back, initiate and/or continue NAC if: 1.

Treatment after bloodwork ¡ After bloodwork is back, initiate and/or continue NAC if: 1. 2. Nomogram indicates probable toxicity. In the setting of a unreliable nomogram* you have: a) b) clinical suspicion of toxicity and Tylenol levels are even detectable. clinical suspicion of toxicity with undetectable Tylenol levels, but AST or other bloodwork is abnormal. 68

Treatment after bloodwork ¡ What if you still have clinical suspicion of toxicity when

Treatment after bloodwork ¡ What if you still have clinical suspicion of toxicity when all your bloodwork is back and it is all completely normal? l l l Chances are, you worry too much. Theoretically (although I never saw this documented anywhere), I suppose there could be a window right around the 24 -hr mark where Tylenol levels were undetect-able but the AST had not yet begun to rise. I would have to have some overwhelming clinical suspicion of Tylenol toxicity before I investigated this scenario further. 69

Treatment Protocols ¡ For uncomplicated Tylenol overdose, there are two types of NAC protocols:

Treatment Protocols ¡ For uncomplicated Tylenol overdose, there are two types of NAC protocols: 1. Oral NAC ¡ ¡ ¡ 2. A 72 -hour course of therapy. 18 total doses (q 4 h dosing). Total dose = 1330 mg/kg of NAC. IV NAC 1. 2. 3. A 20 -hour course of therapy. Continuous IV infusion. Total dose = 300 mg/kg of NAC. 70 #

Treatment Protocols ¡ ¡ For Tylenol overdose complicated by liverfailure, IV NAC is used

Treatment Protocols ¡ ¡ For Tylenol overdose complicated by liverfailure, IV NAC is used but the infusion is not stopped at 20 hours. Instead, the NAC is continued until the patient: 1. 2. 3. Fully recovers. Dies. Receives a liver transplant. 71

– – This is the U. of A. nursing protocol for IV NAC in

– – This is the U. of A. nursing protocol for IV NAC in uncomplicated Tylenol toxicity. (N. B. NAC concentration = 200 mg/m. L) 72

Comparing Treatment Protocols 1. Oral NAC – 2. method of choice in the U.

Comparing Treatment Protocols 1. Oral NAC – 2. method of choice in the U. S. IV NAC – – – method of choice in Canada. typically better tolerated. major limitation is rate-related IV reactions (discussed next slide), which are typically nonserious and easily controlled. 73

Comparing Treatment Protocols • Adverse reactions with IV NAC: 1. 2. Reported frequency is

Comparing Treatment Protocols • Adverse reactions with IV NAC: 1. 2. Reported frequency is 0. 2 – 21% Reported rxns (in order of increasing severity and decreasing frequency): ¡ ¡ ¡ nausea/flushing/chills/fever urticarial rash/hypotension bronchospasm/angioedema hemolysis cardiovascular collapse 74

Comparing Treatment Protocols • Adverse reactions with IV NAC: 3. These IV-related reactions: ¡

Comparing Treatment Protocols • Adverse reactions with IV NAC: 3. These IV-related reactions: ¡ ¡ ¡ are dose- and rate-dependent usually occur in the first hour of Rx are usually easily controlled with: a) b) c) temporarily stopping the IV. treating with antihistamines. re-starting the IV at a (temporarily) lower-rate. 75

Comparing Treatment Protocols • Adverse reactions with IV NAC: 4. Continuation of IV therapy

Comparing Treatment Protocols • Adverse reactions with IV NAC: 4. Continuation of IV therapy is the rule in all but life-threatening scenarios. 76

Comparing Treatment Protocols ¡ Effectiveness of IV vs. oral NAC. 1. 2. In an

Comparing Treatment Protocols ¡ Effectiveness of IV vs. oral NAC. 1. 2. In an uncomplicated Tylenol overdose at <8 hrs, IV NAC is as effective as oral. In an uncomplicated Tylenol overdose at >8 hrs, oral NAC may be superior to IV. l 3. Possibly secondary to the increased amount and duration of oral NAC. * In Tylenol-induced fulminant liver failure, only IV protocols have ever been formally used and studied. 77

Comparing Treatment Protocols 4. Tylenol toxicity in pregnancy has not been rigorously studied, but

Comparing Treatment Protocols 4. Tylenol toxicity in pregnancy has not been rigorously studied, but IV NAC is typically recommended: a) b) c) d) Fetal Tylenol toxicity is rare, but has been reported at all stages of pregnancy. IV NAC is safe and effective in mom. Higher serum levels obtained with IV NAC (by avoiding hepatic first-pass metabolism in mom) may translate into higher serum levels in the fetus. Exact treatment guidelines are controversial, and require toxicological and/or obstetrical consultation. 78

Prognosis 79

Prognosis 79

Prognosis ¡ ¡ ¡ Although AST is the most sensitive marker for Tylenol-induced liver

Prognosis ¡ ¡ ¡ Although AST is the most sensitive marker for Tylenol-induced liver damage, it is a poor prognosticator. Two large studies (>500 patients each)1 established markers for prognosis in hepatic failure. Patients with poor prognostic markers can be evaluated to see if they are eligible for liver transplantation. 80

Prognosis ¡ Following Tylenol-induced fulminant liver failure, patients are eligible for liver transplantation if:

Prognosis ¡ Following Tylenol-induced fulminant liver failure, patients are eligible for liver transplantation if: ** 1. Arterial p. H < 7. 30 (following fluid resuscitation) OR 2. They have all three of the following: a) > Grade 3 encephalopathy * b) INR > 6 c) Cr > 300 -310 ** Cdn adaptation of the King’s College Hospital criteria. 81

Prognosis ¡ Patients who meet these criteria and: a) Get a liver transplant… l

Prognosis ¡ Patients who meet these criteria and: a) Get a liver transplant… l b) have a 66% one-year survival rate. Do not get a liver transplant… l have a 80 -90% mortality rate. 82

In summary… 83

In summary… 83

Idiot’s Guide to Tylenol Toxicity 1. 2. Patient presents with possible Tylenol toxicity. Unless

Idiot’s Guide to Tylenol Toxicity 1. 2. Patient presents with possible Tylenol toxicity. Unless all of the following apply * (in which case you can wait until 4 hrs post-ingestion) immediately draw and send: a) b) c) d) Tylenol levels AST, PT lytes, BUN/Cr, glucose urine for pregnancy testing (women only) 84

Idiot’s Guide to Tylenol Toxicity 3. 4. 5. While the bloodwork is pending, if

Idiot’s Guide to Tylenol Toxicity 3. 4. 5. While the bloodwork is pending, if you are clinically suspicious of potential toxicity, start NAC. When bloodwork is back, if the nomogram can be used, plot the Tylenol level and treat as indicated. When bloodwork is back, if the nomogram cannot be used, rely on combination of bloodwork and clinical suspicion to determine need for NAC. 85

Idiot’s Guide to Tylenol Toxicity 6. If there is yet no indication to treat,

Idiot’s Guide to Tylenol Toxicity 6. If there is yet no indication to treat, consider the possibility that Tylenol levels may still be rising: a) b) ¡ additional Tylenol may have been ingested just before arrival at ED. sustained-release and/or comb-ination Tylenol may have delayed absorption kinetics in overdose. If these apply, draw another set of Tylenol levels and bloodwork in 4 hrs time, and use these to guide your therapy decisions. 86

Idiot’s Guide to Tylenol Toxicity 7. Patients requiring treatment with NAC will also require:

Idiot’s Guide to Tylenol Toxicity 7. Patients requiring treatment with NAC will also require: l l monitoring for hepatic or renal failure. Internal Medicine/Hepatology/ICU consultation if hepatic failure develops Obstetrics/Toxicology consultation if patient is pregnant. Psychiatric consultation if overdose represented a suicide attempt. 87

Final Points to Discuss 1. 2. NAC within the first 24 hrs… no one

Final Points to Discuss 1. 2. NAC within the first 24 hrs… no one dies? True? Charcoal? What do you think? 88

That’s all folks… 89

That’s all folks… 89

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1. 2. 3. 4. 5. References Burns, Ismail, et al. Up. To. Date Online

1. 2. 3. 4. 5. References Burns, Ismail, et al. Up. To. Date Online 12. 2. “Management of acetaminophen (paracetamol) intoxication. ” April 2004. Burns, Ismail, et al. Up. To. Date Online 12. 2. “Pathophysiology and diagnosis of acetaminophen (paracetamol) intoxication. ” April 2004. Canadian Pharmacist’s Association. CPS. 2002. p 175153 Marx, Hockberger, et al. Rosen’s Emergency Medicine. 5 th Edition. p 2069 -74. Tintinalli, Kelen, et al. Emergency Medicine. 6 th Edition. p 1088 -93. 91

THE END 92

THE END 92

Grades of Hepatic Encephalopathy * Clinical Stage Intellectual functioning Neuromuscular function Subclinical Normal exam

Grades of Hepatic Encephalopathy * Clinical Stage Intellectual functioning Neuromuscular function Subclinical Normal exam Subtle changes only Grade I Decreased attention, personality changes Tremor, apraxia, incoordination, Grade II Drowsiness, behavioural Asterixis. slowed speech, changes ataxia Grade III Confusion, disorientation, amnesia Decreased reflexes, nystagmus, clonus, muscular rigidity Grade IV Stupor, coma Dilated pupils, decerebrate posturing 93

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