by Roger Lewis, Revised January 4, 1998

DISCLAIMER: Please note that the research for this essay was done as an independent project and has not been directed by or overseen by any other researcher or investigator. This research is based on high quality references which are listed at the end. All rights reserved.


A comprehensive review of 99 forensic, criminological, and other scientific references was undertaken with regards to analyzing the postmortem blood morphine level of Kurt Cobain. The following essay reports on this review, which includes 19 studies of 1526 deaths specifically involving blood morphine levels of intravenous heroin related overdoses, as shown in Appendix A. Other studies which were reviewed include thousands of heroin-related deaths in general, over 3226 heroin related overdoses, over 3586 suicides, 760 violent suicides, several significant staged deaths, autopsy procedures & discrepancies, postmortem pharmacokinetics of drugs, and, with respect to the traces of a "diazepam-like" substance found in Cobain's blood, several references were reviewed regarding benzodiazepines. Table 1, below, shows a seven point summary of the material reviewed, which provides a clear picture of Cobain's true cause of death, homicide. Thus, in contrast with the "official" verdict of suicide by shotgun, the scientific facts point to a series of events which probably included a massive, lethal "hot shot" dose of heroin and a benzodiazepine administered to Cobain, which would have either immediately rendered him incapacitated in a comatose state or killed him instantly. No suicide or overdose case exists, in any of the many references reviewed, which parallels the Cobain case, most likely because the chain of events which occurred cannot be duplicated. This chain of events specifically resembles homicide patterns, not suicide, and should be re-opened to allow an independent re-investigation of the serious discrepancies in the verdict, which should be changed.

Table 1

7 Point Summary

1.) TRIPLE MAXIMUM LETHAL DOSE EVEN FOR SEVERE ADDICTS: At least three days after his death, Kurt Cobain's blood contained 1.52 milligrams of morphine per litre (mg/L) plus traces of a "diazepam-like" substance. This level is widely known to represent three times the lethal dose of heroin, but it is not commonly understood that this level is three times the lethal dose even for severe heroin addicts. Generally, a blood morphine level of 0.5mg/L is caused by 75 mg - 80 mg of heroin, the established maximum lethal dose, even for severe addicts. A blood level of 1.52 mg/L generally indicates an original dose of approximately 225 mg - 240 mg of heroin.

2.) INCAPACITATED OR DEAD BEFORE GUNSHOT:Large overdoses of heroin by heroin addicts are a phenomenon which is well understood. Research clearly shows that an overdose in the range of that received by Cobain would lead to immediate and complete incapacitation and/or immediate death.

3.) OTHER FACTORS ENSURED OVERDOSE LETHALITY: The 1.52 mg/L blood morphine level does not compensate for the presence of diazepam, or Cobain's low body weight, both of which are well proven to substantially increase the lethality of the heroin.

4.) CASE UNPARALLELED IN SUICIDE & OVERDOSE REPORTS: A review of 3586 suicides, including 760 violent suicides, shows no case involving both a gun and narcotic overdose of any kind, supporting theories regarding the absence or extreme rarity of violent suicide among addicts.

5.) CASE CONSISTENT WITH HOMICIDE PATTERNS: A review of cases involving homicides shows many similarities with patterns in the Cobain case.

6.) OTHER EVIDENCE INDICATES HOMICIDE: Officially acknowledged evidence exists which indicates the possibility of homicide, including a misleading missing persons report, postmortem credit card usage, handwriting discrepancies on the "suicide" note, and the lack of legible fingerprints on the weapon. It appears the police were prejudicially in favour of a suicide ruling, and that the coroner was involved in a conflict of interest predisposing him towards this major discrepancy in the evaluation of his findings.

7.) CONCLUSION: HOMICIDE: The evidence indicates that a massive intravenous dose of heroin, and possibly a benzodiazepine, was administered to Cobain. The final of the two known injections incapacitated and/or killed Cobain, and the gunshot is evidence of a homicide staged to look like a suicide. The case should be re-opened by an independent investigatory body.


Kurt Cobain's untimely death is admittedly a morbid subject. This essay is intended solely to contribute to the efforts of thousands of Cobain admirers and others who seek to put an end to the copy-cat suicides, and to discover the truth behind this horrible tragedy. Estimates from 1995 listed over 150 acknowledged copy cat suicides, some of which are described in Appendix B. Concerns regarding potential lawsuits from bereaved parents against the Seattle Police Department has been suggested to be a factor in their determination to keep the case officially closed unless "new evidence" comes forward. One such piece of new evidence is the following re-interpretation of the officially released evidence. The official time of death is unknown, but is estimated as occurring no later than towards the evening of Tuesday, April 5th, and the body was found Friday, April 8, at 8:40 a.m. This will be the starting point for the following research and observations which attempt to present the facts supporting the claim that Cobain was incapacitated or dead at the time he supposedly shot himself, a situation which would obviously completely eliminate the possibility of suicide. The essay is somewhat technical, so efforts have been made to simplify and explain these matters for those who are not familiar with the scientific nature of this research. Additionally, some are details of the Cobain case are presented for those who are unfamiliar with the case in general.


Cobain's death in April, 1994 led to wide media coverage, and it was soon revealed that his blood morphine level was 1.52 mg per litre (mg/L). One biographer mistakenly claimed that Cobain "injected" 1.52 mg of heroin. The figure 1.52 mg actually refers to the level of drugs found in Cobain's blood, not the amount he originally injected. This can be seen in other reports, both biographical and mass media, where the 1.52 mg level is sometimes further described as "per litre of blood" or "triple the lethal dose," usually with subsequent notes that an addict has higher tolerance. Cobain would have needed to inject much more than 1.52 mg of heroin to help even the most mild headache. Additionally, the Seattle Police Department reported that a cigar box of drug paraphernalia was beside the victim, including pieces of what appeared to be black tar heroin, generally regarded as Mexican in origin. Also, according to the Seattle Police Reports, two puncture marks were found on Cobain's body, one in each arm, in the inside crooks of the elbow region.

The fact that there is "higher tolerance among addicts" is commonly misunderstood. This concept is evoked apparently as an attempt to describe how it could be remotely possible that Cobain was alive and functioning well enough to fire a shotgun, despite the otherwise triple maximum lethal dose. The "1.52 mg" figure refers specifically to the morphine per litre of blood. No doubt exists that a blood level of 1.52 mg of morphine per litre represents just a little bit over three times the maximum lethal dose, but the implications of this fact are not well understood.

Table 2, below, shows that the lethal dose range of intravenous heroin is generally regarded as 10 mg to 12 mg. Sometimes even a tiny dose can kill, so the lethal dose of intravenous heroin can go as low as 3 mg, possibly even lower. Some people get confused and think that high variability in the minimum lethal dose means that a similar variability exists for the maximum lethal dose. The most serious heroin addicts will die with virtual certainty with much less than a dose of 75 mg to 80 mg of heroin. After studying many hundreds of such cases, it is clearly established that 75 mg to 80 mg is the maximum lethal dose for even the most severe heroin addicts. Note that in a low tolerance person, in an average hospital setting, a small effective therapeutic dose of intravenous heroin is only 3 mg to 4 mg. The important thing to note here is that the problems associated with establishing a "lethal dose" for intravenous heroin primarily relates to the problem of establishing a "minimal lethal dose," i.e. the smallest amount of heroin which will kill. The "maximum lethal dose," i.e. the highest dose of intravenous heroin a severe heroin addict can withstand without immediately collapsing into a coma and/or immediately dying, is very well documented. The blood morphine level of 1.52 mg per litre found in Cobain's body represents a heroin dose which is substantially higher than this well established maximum lethal dose.

Table 2

Therapeutic, Toxic, & Lethal Dose Ranges of Intravenous Heroin in
Relation to Low & High Tolerance Levels

Degree of Toxicity or Lethality Dose Range

Therapeutic (low tolerance) 3 mg - 4 mg
Toxic (low tolerance) 3 mg - 10 mg
Lethal (low tolerance) 10 mg - 12 mg
Therapeutic (high tolerance) 10 mg - 60 mg
Toxic (high tolerance) 10 mg - 70 mg
Lethal (high tolerance) 75 mg - 80 mg

The "1.52mg per litre" level in Cobain is one several standard measurements referring to the blood level of morphine. For example, 1.52 mg per litre could also be expressed as "152 mcg per 100 ml," because mathematically they are the same amounts. Those unfamiliar with metric conversions should note that basically, a litre is 1000 ml, so 1 mg per 1000 ml is equivalent to 0.1 mg per 100 ml. Those of you more familiar with metric will note that 100 ml is one-tenth of a litre, thus the abbreviation "dL" stands for "decilitre,"which is of course the very same 100 ml. Throughout this report, whenever a source is quoted using a blood drug amount in a format other than mg per litre, I have supplied a non-italicized, bracketed conversion following the quoted figure, eg. "93.0 mcg/dL...(0.93 mg/L, ed.)."

Approximately 25 years ago, it became increasingly clear that accurate postmortem detection of morphine in blood was a problem which had finally been resolved scientifically. Garriott & Sturner, in 1973, note that "With the recent advent of improved methodology for the determination of morphine in the has now become possible to quantitate small amounts of this narcotic drug metabolite some time after the last previous heroin injection (28)." Nakamura explained in 1979 that "Until recently, the toxicologic determination of heroin death was extremely difficult because of the lack of a sensitive method for the detection and quantitation of small amounts of morphine in postmortem blood and other tissues. " (63). Data is not available regarding the testing method used to determine the level of morphine in Cobain's blood, although the scientific literature suggests strongly that GC (Gas Chromatography) is the current standard method. Other major testing methods exist, such as GLC (Gas-Liquid Chromatography), GC-MS (Gas Chromatography-Mass Spectroscopy), HPLC (High Pressure Liquid Chromatography), RIA (Radio-immuno Assay), and all of these methods have been determined to be very reliable indicators for establishing the levels of morphine in postmortem blood.

There will be no discussion blood "heroin" levels, because heroin is almost instantly transformed into morphine when it enters the blood. Heroin itself can indeed be measured in the blood and other tissues, especially the urine, but it should be noted that heroin levels are largely irrelevant to this case. Special laboratory conditions are often elaborately constructed to measure these actual "heroin levels," because in everyday life they almost never exist. Again, simply put, when heroin is injected into the blood it rapidly transforms into morphine. There is virtually no heroin left in the blood as "heroin" after about nine minutes, with the heroin going through a deacetylation process, sometimes called de-esterfication. This is known as a "pharmakokinetic" process, and is known to continue after death. Consequently, it is virtually always that morphine, instead of heroin, is measured in the blood of both the living and dead to give forensic scientists an indication of the amount of heroin originally injected, the likely time of injection, and very importantly, an indication as to the events following the injection.Morphine toxicity, whether found in the blood, bile, urine, liver, or other tissues, is the standard measurement for opioid toxicity in general, and heroin in particular, because heroin immediately turns into morphine in the body.

One study involved a small group of severe addicts who used high doses ranging from 150 mg to 200 mg of morphine four times daily (75). This is equivalent to an intake of approximately 45 mg to 60 mg of heroin, four times daily. These addicts showed some signs of serious effects, but continued for several years without fatality and showing average blood levels of 0.3 mg per liter. Another study points to the potential lethality of even low doses, with 5 fatalities showing an average of a mere 0.021 mg per liter of blood, representing an approximate intake of 3 mg, i.e the average functioning dose. The average person without pain or addiction will overdose with 60 mg of morphine (18 mg heroin), yet a patient in serious pain will likely require the same dose, 60 mg of morphine (18 mg heroin) to relieve such serious pain symptoms. Platt also mentions a particular study where severe heroin addicts were monitored, and the maximum dose seen was a daily total of 260 mg heroin, taken in four divided doses, i.e. 65 mg heroin each dose (75). Again, the maximum lethal dose of heroin is shown to be 75 mg - 80 mg for a 150 lb. severe addict. Such a lethal dose, of about 75 mg - 80 mg heroin, will give the soon-to-be-dead individual a blood morphine level of approximately 0.5 mg of morphine per litre of blood. Astonishingly, this is less than one-third of the level that was found in Cobain's tiny body at least three days after his death.

Table 3

Dose Equivalents of Heroin & Morphine

Drug Equivalent Dose

Heroin 3 mg

Morphine 10 mg

Table 3 shows that heroin is approximately 3 to 4 times stronger than morphine, so 3 mg of heroin is equal to about 10 mg of morphine. It should be noted that generally the data is very supportive of this equivalence between certain doses of morphine and heroin, an equivalence which is three-fold, including pharmacological effect, blood morphine levels, and most importantly, toxicological effect. To the extent that differences have been established, there is no doubt that a large intravenous heroin overdose is even deadlier and faster acting than an "equivalent" large intravenous morphine overdose.

Table 4, below, shows the generally accepted dose and blood level equivalents of intravenous heroin. More than 100mg of morphine (30 mg heroin) almost always presents major complications. Doses over 250mg morphine (75 mg - 80 mg heroin) are usually associated with certain death, i.e. 75 mg - 80 mg of heroin, leads to a blood level of approximately 0.5mg per liter, the high end of toxic doses. Thus it is clear that Cobain ingested at least triple the lethal dose for even the most severe addict. This is basically a linear conversion, which is not true for all drugs, but is shown to be true for intravenous morphine and heroin overdoses in addicts, as shown in the several of the studies referenced. If he were not a severe addict, then 1.52 mg per liter potentially represents up to 75 times the lethal dose. Details regarding common heroin doses are explained by Tong & Pond who state that "the basic unit of sale is the 'tenth,' which is 1/10 of a gram or 100 mg of pure drug. This unit...provides approximately 4 'hits' or doses. A quarter of a tenth (25 mg powder) contains 20 mg to 24 mg of heroin, which is more than the usual street addict is used to per dose." (94). Severe addicts may require 3 such hits in 1 dose, 4 times daily, while Cobain's blood morphine level represents a dose of approximately 8 to 10 such "hits." More importantly, it must be remembered that the actual size of the dose does not matter very much, rather it is the blood morphine level in particular, a what it tells us, which is the true forensic evidence, the incontrovertible fact. Although it is definitely possible to make a reasonable estimate at the obviously massive dose Cobain received based on data from other intravenous heroin overdoses in addicts, an exact dose figure cannot be determined without a full forensic report regarding the morphine levels in various other organs and tissues. Regardless of the specific dose of heroin, the 1.52mg/L blood morphine level in Cobain allows for the conclusion to be made that he was immediately incapacitated or dead based on the simple fact that no other instance exists on record indicating otherwise, even remotely.

Table 4

Dose & Blood Level Equivalents of Intravenous Heroin

Dose Equivalent Blood Morphine Level

75 mg - 80 mg 0.5 mg/L

150 mg - 160 mg 1.0 mg/L

225 mg - 240 mg 1.5 mg/L

The overall importance and relevance of such toxicological data is emphasized eloquently by Prouty, et. al., as "One of the most fundamental questions of postmortem forensic toxicology is...'How much drug did the decedent take?' Historically, to answer this question, toxicologists have relied upon published case reports of fatal intoxication, in which the amount of ingested drug was known or reasonably approximated, and upon reports in the clinical literature that contain information concerning drug concentrations after single or chronic dosing. In recent years, pharmakokinetic equations have been increasingly used in an effort to estimate more precisely the total amount of a drug in the body and, subsequently, estimate the dose of the drug required to produce a measured blood concentration." (76). The use of blood morphine levels to establish criminal intent dates back over 100 years. Nakamura points out that "As early as 1893...Thorwald describes a celebrated court proceeding involving a physician who allegedly poisoned his wife with morphine." (63).

Analyzing the morphine level of a dead person can help determine the time and the manner of death. Such tests are useful in cases where there is no eyewitness, or, for example, in the Cobain case, where there are officially no witness, but where forensic evidence suggests the presence of a witness, i.e. Cobain was either dead or so severely incapacitated by the massive dose heroin, that someone else had to have pulled the trigger. Nakamura remarks similarly that "Many...witnesses are unavailable because they either flee from the scene upon the death of their companion or they discard the body in a location less discriminating than their own domicile." (63) Thus the very idea of investigating a suspicious death using forensic testing of the morphine levels is a well established phenomenon, due at least partly to the tendency of those associated with the event to flee, discard the body elsewhere, and provide otherwise unreliable information in an attempt to avoid implication of their involvement. With respect to Nakamura's comment regarding "...they discard a body in a location less discriminating than their own domicile," it is noteworthy that Cobain's body was suspiciously enough found in his own domicile, even though he was supposedly a "missing person."


The following quotes from Krivanek describe the rapid action of this deadly narcotic, especially when taken intravenously, "Heroin has a far more positive slope than either morphine or methadone- that is, its effects begin, and reach a peak more rapidly...3 mg of heroin...given by subcutaneous injection will provide adequate analgesia in about 70 per cent of patients with moderate to severe pain. At that dose sedative effects and respiratory depression should both be minimal. As dose increases, they become more pronounced, and the respiratory depression will become life-threatening with about 30 mg morphine (9 - 10 mg heroin, ed.) ...Intravenous doses, on the other hand, can be considerably smaller, - about one-fifth of the subcutaneous dose." (53). Additionally, Platt remarks on the amazing rapid action of intravenous heroin by explaining that "...the high uptake of heroin...indicates that an abrupt entrance of heroin into brain tissue probably occurs 10 to 20 seconds after the usual intravenous injection by addicts...15 seconds, 68% uptake into brain with heroin compared to 42% for methadone, 24% for codeine, and morphine too small to measure. " (75). It would be a mistake to think that even a severe addict could intravenously inject triple the maximum lethal dose of heroin and survive 10 to 20 seconds. First, it must be understood that the injection process itself takes a considerable amount of time such that the lethal effects of the drug often take effect with the needle still in the arm. This specific case supposedly involved the injection, the removal of the needle & tourniquet, the placement of paraphernalia in a box, sitting on the floor, and positioning and firing the shotgun. Secondly, it is important to note that an intravenous heroin overdose is very different from the previously described "usual injection" because an overdose produces much more serious effects much faster than the "usual injection".

The Lange manual for Poisoning & Drug Overdose states that for opiates, "with higher doses, coma is accompanied by respiratory depression and apnea often results in sudden death." (68). Basically, a high lethal dose of heroin will either cause immediate death, or, in an unlikely scenario, immediate incapacitation by rendering the recipient comatose. This is described by Staub, et. al. as follows: "...we have shown that in 85% of the cases, the death should be attributed to a so-called 'golden shot'. In the remaining cases, the death is not so rapid and a survival period in a comatose state has to be taken into consideration." (90). Similarly, Garriot & Sturner, describe how "...morphine in the blood was found to correlate with the time of survival and ranged from 10 to 93 mcg per 100ml (.1 to .93 mg per litre, ed.) in the short-term interval group." (28). Notably, as of 1973, Garriott & Sturner did not find any blood morphine level over 0.93 mg per litre, i.e. Cobain's blood level was over 50% higher than the highest level they had ever encountered. Regarding the common sequelae of heroin overdoses, Nakamura explains " there are vivid accounts of victims lapsing into a deep coma immediately following a 'fix' with a syringe still afixed in the arm or on the floor underneath the body, and/or with an improvised tourniquet still in place around the arm." (63). Gossell & Bricker report that "for a large overdose, the victim rapidly lapses into coma and is not arousable by verbal or painful stimuli." (32).

Garriott & Sturner describe the relation between dose and speed of death as follows: "The cases in the intermediate-survival range - namely, from three to 24 hours - showed values for morphine in the blood of 3 to 10 mcg per 100 ml (.03 to .1 mg per litre, ed.). ...It is of interest that the three cases in the short-survival group demonstrating the highest concentrations of morphine in the blood (50, 50, and 93 mcg per 100 ml) (0.5, 0.5, and 0.93 mg per litre, ed.) showed neither froth in the air passages nor extensive pulmonary edema, supporting the concept that a very sudden death may be due to other mechanisms after injection. Rapid central-nervous-systems and respiratory depression as a direct effect of the narcotic drug would account for this phenomenon. ...(ed. note: as of 1973) The highest observed blood morphine value in an acute heroin "overdose" is 100 mcg per 100 ml (1 mg per litre, ed.). ...relatively high concentrations of free morphine tend to indicate the importance of the final injection in producing the lethal reaction." (28). Nakamura explains "In more cases, it can be now shown that narcotic was taken and rapidly distributed by the body to the various organs, and it may now be unnecessary to explain narcotic deaths by blaming excipients or hypersensitivity responses." (63). Thus, although some rare overdoses can be attributed partially to hypersensitivity, allergic, and other reactions to adulterants in street heroin, it is now widely accepted that heroin overdoses are primarily dose related.

Some confusion exists in the literature regarding estimates of "speed" of death following intravenous heroin overdose, primarily due to two reasons. The first reason for confusion concerns the minimum lethal dose, i.e. a small blood morphine level does not rule out instant collapse or death. The second reason for confusion concerns the true nature of death, which technically involves the death of different organs over a period of time. Burgess describes this as "Death does not occur all at once. One organ or system of organs may die some time before another." (8). Thus, even in those rare cases when an addict takes a large overdose and does not immediately die, immediate incapacitation occurs via a coma, and a comatose person may continue to technically "live" for hours or even days. The variability in survival periods specifically concerns the lower doses, not the higher doses, and when it comes to "massive" doses, eg. the Cobain case, the data is remarkably clear in stating that such a dose would immediately incapacitate even a heroin addict with the highest of tolerance levels.

One specific case which bears special significance with regard to the Cobain case is the case of Cindy James. The James case, as described by Dinn (20), involves the tragic death of a nurse who was reported as missing for two weeks before she was found dead. The case was changed from a suicide verdict to a verdict of "undecided," and the basic point of comparison concerns the methodologies used to reach the change in verdict. Before continuing with the similarities between the James case & the Cobain case, it is important to note several differences. The James Case did not involve a gun, there was no drug paraphernalia found near the body, and there was evidence that she was mentally unstable and possibly staged her own death to appear as murder. Also, James received morphine, not heroin (heroin is significantly faster and stronger than morphine). The cases are similar in that both James and Cobain died of a massive drug overdose which appeared to police, initially at least, to be suicides, and which later, to varying degrees, were suggested to be homicides based significantly upon the massiveness of the overdoses in relation to degree of incapacitation and speed of death.

It was conclusively determined that if the scenario of intravenous injection was indeed true, then "Following an injection, morphine at this concentration would have induced a rapid state of unconsciousness and death...Given the level of consciousness and the time required to create the scene...then the death would appear to have been a homicide." (20). Thus it is important to note that the only reason the case was not then determined to be a homicide is because there was no way to verify whether the morphine was taken orally or otherwise. The mere possibility of murder was enough to change the James verdict to "undecided," even though the case involved significant evidence of suicide. The James case establishes an important precedent of methodology, which is that the blood levels of morphine can be used to determine time of death and/or incapacitation with regards to recreating the events surrounding the death in question for the purposes of determining whether the death was due to murder or suicide. The same methodology, when applied to the Cobain case, indicates that due to death or incapacitation following the intravenous injection of a massive lethal dose of heroin (much stronger than morphine), Cobain's death would be even more certainly a homicide.

Nakamura conducted a study in which he "..selected for toxicologic analyses seven cases of heroin fatalities in Los Angeles County, all of whom had a common history of what appeared to be sudden death. ...The blood level of morphine ranged from 0.2 to 1.0 mcg/ml." (0.2 to 1 mg per litre, ed.). "Blood morphine levels in most acute heroin-involved deaths range from 0.1 to 1.0 mcg/ml (0.1 to 1.0 mg per litre, ed.)...Blood levels of morphine also appear to be regulated by dosage." (63). Only one case in the 7 case study by Nakamura had a blood morphine level in Cobain's range, at 1.8 mg per litre, and the next closest was 0.9 mg per litre. The rest were 0.5 mg per litre and lower, with levels as low as 0.1 mg per litre causing immediate death. Nakamara also refers to his related 1974 doctoral thesis from the School of Criminology at the University of California, Berkely, where he "...examined blood specimens from 64 fatalities...whose survival time could be estimated." The highest blood morphine level was 0.8 mg per litre, and there was a clear indication that the higher the dose, the faster the death.


A blood morphine level of 1.52 mg/L indicates a heroin intake of approximately 225 mg - 240 mg. Thus, despite suggestions that Cobain may have simply been incapacitated by a normal, large dose fit for an addict, it must be noted that his body weight was at highest 130 lbs., and he was listed as being 115 lbs. in late 1993. This would generally increase his susceptibility to overdose by as much as 20%, since toxicity data is based on a 150 lb. adult.

Heroin purity has been shown to vary widely, with samples containing as little as 1% heroin. Mexican black tar is usually no higher than 40% pure, but is not uncommonly up to 80% pure, while highest recorded purity level for Mexican black tar heroin is 93% pure (89). If the heroin used in this case was indeed Mexican black tar heroin, and it was in the range of the highest potency recorded, i.e. 93% purity, then the dose required to reach a blood morphine level of 1.52 mg per litre would be approximately 245 mg to 260 mg. Whatever the physical source of heroin was, it does not really matter; the only thing that makes one type of heroin stronger than another is concentration of dose, so it was approximately 225 mg to 240 mg of some type of heroin. If the purity was 40%, a more common figure, then the lethal dose, including adulterants, would have been around 600 mg. Thus there is a definite chance of up to 350 mg of procaine or acetyl procaine as an adulterant. Note that procaine is commonly found in samples of Mexican black tar heroin. Regarding the potential toxicity of procaine, it should be noted that procaine levels would likely be undetectable in Cobain's blood due to the fact that the body was found at least three days after death. Still, the importance of procaine's potential toxicity is emphasized by Nakamura, who says "Nearly all the contraband heroin in the western areas is obtained from Mexico and contains an appreciable amount of procaine, or acetyl-procaine, as a filler material. ...The potential danger of a large concentration of this dilutent in street heroin needs to be better understood. (63).

Diazepam is generally synonymous with the more well-known drug Valium, and sometimes the term diazepam refers to the generic category of drugs known as benzodiazepines. This class of drugs is regarded as sedative-hypnotic, and is not cross-tolerant to opioids. That means addicts can use diazepam and similar drugs in the same way that non-addicts use them. Conversely, even a heroin addict will experience toxicity to benzodiazepines in the same manner as a non-addict. A junkie is not immune to the toxic effects of a benzodiazepine overdose simply because he or she can handle a big dose of heroin. Cassidy, et. al. report "as both drugs cause respiratory depression...the likelihood of death resulting as a greater than if either drug were taken alone." (10). Oldendorf reports on the effect of relaxation as increasing heroin absorption in the brain (67), a factor which addicts often attempt to manipulate, eg. by using heroin with a relaxant such as a benzodiazepine.

Diazepam poisoning in particular, and benzodiazepine poisoning in general, is rare in isolation, but not at all uncommon in combination with other similar drugs, notably heroin. Several current studies from sources as disparate as the USA, Australia, Denmark, and the U.K., show that benzodiazepine abuse frequently occurs with heroin abuse, and that resultant death is a serious, growing concern. The two drugs have a definite added effect, increasing the likelihood of respiratory failure associated with heroin overdose by a very significant amount, which has now been relatively well quantified. The lethality of the combined use of heroin and diazepam are discussed by Nakamura, who mentions them in reference to occasional problems with finding a postmortem blood morphine level. The lethality of the heroin is so greatly increased that very small doses kill, meaning that "...the interaction of drugs in eliciting acute responses and causing deaths even when sublethal amounts of two or more drugs are present in postmortem specimens from the same cadaver may be a factor." (63).

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