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Laboratory study of the effects of citric and ascorbic acids on injections prepared with brown heroin
This paper is reproduced
by the first author from a paper published in the International Journal
of Drug Policy 11(6): 417-422.
Jenny Scott*1 BSc, MRPharmS, Arthur Winfield2 BPharm,
PhD, MRPharmS, Emily Kennedy3 BSc, PhD, MRPharmS, and Christine
Bond4 BPharm, MEd, PhD, MRPharmS.
*Corresponding author.
1.Department of Pharmacy and Pharmacology, University of Bath,
Bath, BA2 7AY, UK. email: prsjs@bath.ac.uk
2.School of Pharmacy, University of Kuwait, Kuwait.
3.Boots the Chemists Ltd, UK.
4.Department of General Practice and Primary Care, University
of Aberdeen, UK.
The work presented in this paper was undertaken by J.Scott as part of
a PhD project. The other authors are supervisors to this project. This
paper was written by J.Scott, who’s opinions are expressed herein.
The other authors reviewed the paper for scientific content and clarity.
KEYWORDS: citric acid, ascorbic acid, brown heroin, purity.
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Abstract
The addition of acidic
substances to brown street heroin to facilitate the solubility of diamorphine
in the injection preparation process is commonplace amongst UK injectors.
Knowledge of the chemistry behind this process supports the need for this
stage in the injection preparation process. It is currently illegal, under
the Misuse of Drugs Act, section 9A, to supply acidifiers and other paraphernalia
to injectors in the UK. In the current climate of evidence-based practice,
any consideration given to changing the law would look for evidence to
illustrate that the paraphernalia was necessary. Although the theory behind
the use of acidifiers suggests they are essential, no work using street
heroin has actually been reported to illustrate this fact. Anecdotal information
has found some drug users being told by service providers that the addition
of acids is unnecessary. The provision of inaccurate information in one
area may lead to a lack of trust of all information provided, so it is
important that drugs services give credible information to their clients.
The small study reported here investigated under controlled laboratory
conditions, the effects citric acid and ascorbic acid (vitamin C) on injections
prepared with brown heroin, simply to demonstrate the need for acidifiers
in the injection preparation process.
keywords: citric, ascorbic, vitamin C, brown heroin.
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Introduction
In the UK, ‘street’ heroin is commonly of the type referred
to as ‘brown heroin’. Analytical studies have shown brown heroin
to frequently contain diamorphine (the main psychoactive drug in heroin)
present in the chemical form referred to as basic (Kaa, 1991, Chaudron-Thozet,
1991). Basic diamorphine has a solubility of 1 in 1700 parts of water
(Moffat, 1986), which means that very little will dissolve when mixed
with small amounts of water alone. When injecting drug users (IDUs) prepare
injections with brown heroin, they are known to add acids such as citric
acid or ascorbic acid (vitamin C) and heat the heroin in water on a metal
spoon to convert the base heroin to a more soluble form (Derricott et
al, 1999). i.e.
diamorphine base +
citric acid => diamorphine citrate
Anecdotal observations of the researcher and others have found some drugs
workers to be informing clients that the addition of acids is unnecessary
and the same effects can be achieved by heating the mixture for longer.
The chemistry behind the addition of acids to heroin suggests this not
to be the case. Without the addition of the acid the chemical complex
between the diamorphine and the acid would not be able to happen. However,
a search of the literature found that this had never actually been reported
from work using real street heroin.
In the UK it is against
the Misuse of Drugs Act (section 9a) to supply injecting paraphernalia
to IDUs. Included in this is the supply of acidifiers. Although the chemistry
behind their use suggests they are necessary, evidence of their effects
from laboratory experiments using brown street heroin was considered useful,
to support those health authorities and drugs agencies who are applying
for exemption from prosecution to enable them to distribute paraphernalia
to IDUs as part of their harm reduction schemes.
This paper reports the results of a small laboratory investigation into
the effects of citric and ascorbic acid on injections prepared with street
heroin. The injection preparation process used in the laboratory was based
on safer injecting information and information gathered from heroin injectors,
using semi-structured interviews (n = 19). The interview methods and results
are not reported in this paper, but are available from the corresponding
author. Small quantities of acids, as recommended in safer injecting leaflets
were used and their effects on the heroin investigated. The quantities
were then varied to illustrate the effect of this.
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Mrthods
Following permission from the UK Home Office, the Crown Office for Scotland
and the Procurator Fiscal for Grampian, seized samples of brown heroin
were obtained from the local police forensic laboratory. The percentage
content of diamorphine was established. The amount of heroin used in the
experiments was 250 mg, which was based on the most commonly used quantity
reported by the IDUs who were interviewed, described as ‘a quarter
gram’1.. Difficulty arose in establishing whether
‘a quarter gram’ as purchased from a dealer was actually 250
mg in weight. Information from the police on quantities of seized drugs
suggested that the weight of a wrap considered to be for personal use
varied greatly with maximum weights seen being around 330 mg. Therefore,
since 250 mg was within the range of the seized wraps, this quantity was
used. The quantity and purity of the heroin used by IDUs will of course
vary. Citric acid and ascorbic acid were chosen for investigation are
they are known to be used by IDUs (Derricott et al, 1999) and were reported
as being used by the interviewed IDUs. To establish a weight for ‘a
small pinch’, as recommended in the safer injecting leaflets, ten
small pinches of citric acid were weighed and the average weight taken.
Equal weight of ascorbic acid was used to allow the two results to be
compared.
1. One
gram contains 1000 milligramms (mg)
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All factors used in the preparation process had to be measurable, so they
could be kept constant, to allow comparison of the results. The process
used is shown in figure 1. The stages in the preparation process were
identified from safer injecting advice (Exeter Drugs Project, 1991, HIT,
1995) and the information gathered from the IDUs interviewed. The quantities
used were based on information gathered from the IDUs. The end-point for
the heating was described by the interviewees as being when the mixture
began to bubble and the clear liquid separated from the undissolved material.
The process factors such as the height of the spoon base from the flame,
temperature of water added and length of time of heating were measured
for the first injection prepared and kept constant.
Figure
1: Stages in the heroin preparation process simulated in the laboratory
The amount of diamorphine
in the resulting injections was measured using an analytical process known
as Capillary Zone Electrophoresis (CZE). Details of this equipment, the
analytical materials used and the laboratory techniques are given in appendix
1 of this paper. The quantities of citric and ascorbic acids were also
varied to illustrate the effect this had on the amount of diamorphine
in the resulting injections. The amounts used were approximate multiples
of the weight used to represent one ‘small pinch’. The injections
were filtered with a piece of filter from an unsmoked cigarette. Each
injection was analysed three times and the average results used to calculate
the amount of diamorphine in the injection. Each quantity of acid was
tested three times and the average diamorphine content in the three injections
calculated. An injection was also prepared without the addition of acid.
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Results
The diamorphine content of the heroin was found to be 56 %.
Ten small pinches
of citric acid were weighed and the average weight found to be 15 mg.
Approximate multiples of this quantity which were also investigated were
7 mg (‘half a pinch’), 3 mg (‘a quarter a pinch’)
and 30 mg (‘two pinches’). The ascorbic acid was restricted
to two quantities due to the limited amount of heroin available. These
quantities were 15 mg and 60 mg.
Figure 2 shows the effects of varying the quantity and type of acid in
the preparation of heroin injections.
Figure
2: Effect of quantity and type of acid on amount of heroin in injections
The injection prepared without the addition of acid could not be filtered,
as the solid heroin did not dissolve in the water. Attempts to filter
it were unsuccessful. Instead a precipitating effect was seen.
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Discussion
Figure 2 illustrates how, as expected, the quantity of diamorphine in
the resulting injections increased as the quantity of citric acid increased.
The inability to produce an injection when no acid was added, coupled
with the data in figure 2, supports the chemistry that shows that the
addition of acidifiers is a necessary stage in the injection preparation
process used by IDUs. Therefore, advising that the addition of acid is
unnecessary is incorrect.
Different purities of heroin will require the additons of different amounts
of acid. Concerns around tissue and vein damage from the use of too much
acid have led to safer injecting advice telling IDUs to use as small quantities
as possible, which seems vague. This leads to the question of whether
more accurate information can be given on the quantities of acidifers
required. The diamorphine content in the herion used for this work was
found to be 56%, which means 140 mg of diamorphine was present in the
250 mg quantities used. The question of how much acid would be needed
to dissolve all this diamorphine can be addressed using chemistry calculations.
Chemicals are compared by using a term called ‘moles’. One mole
of any chemical contains the same number of molecules, although the weight
of one mole will vary between chemicals as the molecules have different
sizes of structures. Based on chemical values known as pKa, it is known
that for every mole of diamorphine base, a third of a mole of citric acid
is needed to completely convert the diamorphine to the soluble citrate
form. For ascorbic acid, the pKa values tells us that for every mole of
diamorphine base one mole of ascorbic acid is needed. In weight terms
a mole of diamorphine base weighs 369.4g, a mole of citric acid weighs
192.1g and a mole of ascorbic acid weighs 176.1g. Therefore for every
369.4g of diamorphine base, 64.03g of citric acid or 176.1g of ascorbic
acid would be needed to completely convert the base to a soluble salt.
When this calculation is performed using the 140mg of diamorphine base
that was in each 250mg quantity of heroin, it can be calculated that the
amount of citric acid needed to fully dissolve all the diamorphine would
be 24.3 mg. For ascorbic acid the quantity would be 67 mg. From fig. 2
it can be seen that for the 30 mg of citric acid experiments and 60 mg
of ascorbic acid experiments, which used quantities close to these amounts,
the amount of diamorphine in the prepared injections was not close to
140 mg. In order to establish where the diamorphine may have been lost,
various parts of the preparation process were tested. Diamorphine was
detected in the filters, on the tip of the needle sheath used to stir
the mixture, in the residue left on the spoon after preparation and in
the vapour which evaporated from the spoon on heating. Although not investigated,
the last point suggests that heating the mixture for longer would only
serve to evapourate more of the diamorphine.
Without a knowledge of the amount of diamorphine in heroin, IDUs cannot
be accurately advised on the quantity of acid needed. If the purity of
the diamorphine could be determined, for example through providing a testing
facility, accurate calculations could be made, allowing the amount of
diamorphine injected to be controlled. This may be considered a harm reduction
intervention as records could be kept on the ‘dose’ used an
individual uses and the risk of overdose from unexpectedly high amounts
of diamorphine in street heroin could be reduced. However, it may also
be viewed as helping people to inject and too radical for contemplation.
The issue of providing testing facilities for heroin users is a matter
open for debate.
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Conclusions
These experiments illustrate the point that injecting drug users do need
to add acidifiers to heroin that contains diamorphine base, mostly brown
heroin, in order to dissolve the drug. Telling drug users that acids are
not necessary is false information and telling them to heat the heroin
mixture for longer is likely only to increase the loss of drug during
preparation. An amendment to section 9a of the Misuse of Drugs Act, as
currently proposed by the Home Office (http://www.drugs.gov.uk/ -release date 18.11.02 consultation closes 14.02.03), would allow the
legal supply of acidifiers and other paraphernalia to injectors in the
UK.
The quantity of acidifier
required will vary depending on the acid used and the purity of the heroin,
a factor that is not known exactly. Therefore the judgement of the IDU
will be the only factor that can determine an approximate amount of acid
needed. This opens the debate for the provision of drug testing facilities
for heroin users. A knowledge of the diamorphine content in a sample of
street heroin and confirmation of it’s presence in the base form,
would allow calculation of the amount of acid needed to dissolve the heroin.
This could avoid the use of excessive amounts of acid, which may potentially
have long-term health benefits in reducing vein damage.
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References
CHAUDRON-THOZET, H., GIRARD, J., and DAVID, J.J., 1992. Analysis of Heroin
Seized in France. Bull. Narc, XLIV(1).
DERRICOTT, J., PRESTON, A., and HUNT, N., 1999. The Safer Injecting
Briefing. Liverpool: HIT.
EXETER DRUGS PROJECT, 1992. What Works? 2nd ed. (booklet). Exeter.
HIT, 1995. A Guide to Safer Injecting. (booklet). Liverpool: HIT.
KAA, E., 1991. Street Drugs in Denmark. J. Forensic Sci., 36(3),
866-879.
RUNCIMEN, Viscountess., 2000. Drugs and the Law: Report of the Independent
Inquiry into the Misuse of Drugs Act 1971. London: The Police Foundation.
MOFFAT, A.C., 1986. (Ed). Clarke’s Isolation and Identification
of Drugs in Pharmaceuticals, Body Fluids and Post Mortem Materials,
2nd Ed. London: The Pharmaceutical Press.
TAYLOR, R. B., LOW, A. S, and REID, R. G,. 1996. Determination of Opiates
in Urine by Capillary Electrophoresis. J. Chromatogr. B: Biomedical
Applications. 675: 213-223.
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APPENDIX 1
Analysis equipment
The analysis technique
used was that described by Taylor et al, 1996, using a detection wavelength
of 220 nm. The CZE analysis equipment was made by ISCO, model 3850. The
capillary was of unmodified silica, 50 µm in diameter and 60 cm
long. It was made by Lincoln ISCO, Quality CE. The data was recorded on
an ABB Servogor SE120 chart recorder. Validation showed the method used
to give a linear response over the concentration range of interest.
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Materials
Citric acid B.P (Thornton
& Ross, Huddersfield, UK) and ascorbic acid B.P (vitamin C powder,
Boots the Chemists, Nottingham, UK). The standard reference materials,
diamorphine (DM Wood, Aberdeen, UK) and levallorphan (Sigma, Poole, UK)
were both of pharmaceutical grade. The methanol (Ratheburn, Walkerburn,
Scotland, UK) was of HPLC grade and the water was prepared in house to
HPLC grade using the Millipore Milli-Q system. The cigarette filters were
prepared by removing the filter from an unsmoked cigarette (Lambert and
Butler, UK) and dividing it in four. One segment was used per injection.
The insulin syringes used were 1 ml capacity (B-D, Oxford, UK).
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Experimantal procedure
Results from the analysis
of a solution of diamorphine of known concentration (9.3 µg ml-1)
were established and used to allow the amount of diamorphine in the injections
to be calculated. The levallorphan was used as an internal standard for
the following reason. The analysis equipment produced output data in the
form of peaks which represented the detected drugs. However, the height
of these peaks with a given concentration of drug was shown by Taylor
et al (ibid.) to vary with each analysis run. However, if two drugs
are analysed, the ratio between the height of two peaks will not however
vary. Levallorphan (10.2 µg ml-1) was used as the second
drug against which the peak height ratio was calculated. The ratios were
calculated from the analysis of the solutions of known concentration and
the ratio between the peak of the unknown concentration (the injections
prepared with heroin) and the levallorphan were compared to calculate
the concentration of diamorphine in the injections.
The injections were prepared as described in figure 1 of the main text.
As they were too strong to analyse ‘neat’, they were diluted
by the addition of enough methanol to give 100 ml solution. 1 ml of this
solution and 1 ml of the levallorphan standard solution were mixed and
made up to 10 mls with water. This solution was then analyzed immediately
and the dilution accounted for in the calculations.
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