21 3 / 2014
I give you the holy grail: A pdf of techniques used by forensic dudes to find out which technique is used to find the amounts of which drug. or more specifically, it is literally a practical handbook on what to use and how to use it for the drug - like which mobile phase to use for opioids etc etc etc. It also contains info on:
Prohibited Substances (roids brah)
Use your uni login to see it or message me for a copy
21 3 / 2014
So apparently I have been blogging all wrong. My highly informative immaculately organised, Harvard referenced blog of awesomeness was too good and so the man has told me to step down. Unfortunately I can not tell the man to leave me be for the blogs will represent what I write in my wiki - basically yeah, I’ll end up plagarising myself if I were to copy paste my blogs over (my initial plan) which sucks and would have been SO MUCH MORE FRIGGIN HELPFUL IF I KNEW IT 3 STINKIN MONTHS AGO.
So expect a drop in quality for the next blog.
16 3 / 2014
Mechanism of the mechanism within the mechanism for the mechanism in regards to the mechanism of action. Word.
Aite, enough of the whole broad spectrum shotgun approach to discussing opioids. Let’s go into some proper biochem depth. We talkin bout receptors, ligands agonist and antagonists all up in this blog.
So, the main receptor we discussed was none other than the μ-opioid receptor. Now the μ receptor comes in 3 forms which are so aptly named μ1, μ2 and μ3. Pretty much all of our opioids act upon the μ1 receptor to produce their effects but how exactly do they produce their effects?
Well, the opioid receptors are examples of G protein coupled receptors and they act as follows (summarised):
- Ligand binding causes…
- G-protein activation (GDP exchanged for GTP)
- Dissociation of the Heterotrimer (αβγ subunits), which causes
- Activation of enzyme Adenylate Cyclase (AC)
- AC converts ATP to cyclic AMP (cAMP)
- cAMP causes the activation of the enzyme protein kinase A (PKA) which causes
- Phosphorylation of various intracellular proteins = activation
Activation then leads to the inhibition of neurotransmitter release by (Akil and Simon, 1993; Reisine and Bell, 1993 and Dickenson, 1994):
- Inhibiting calcium entry by blocking and inhibiting N-type Ca++ channels leading to an inhibition of neurotransmitter release (specifically substance P and glutamate)
- Enhancing outward movement of potassium ions by opening voltage-dependant K+ channels leading to a decrease of intercellular K+ leading to the cell becoming hyperpolarised – when the negative potential of the cell is increased thereby preventing excitation or propagation of action potentials.
- Inhibiting adenylate cyclase (AC), the enzyme that breaks down adenosine triphosphate (ATP) to form cyclic adenosine monophosphate (cAMP). Inhibition of adenylate cyclase may result in inhibition of neurotransmitter release.
So that’s the big opioid receptor done. I’ve still got NMDA receptors and nicotinic receptors (methadone’s mechanism of action) left to talk about but its top gear time! I’ll probably try posting em up tonight. If not, then next week fo sure!
Akil H. and Simon EJ., (1993), Opioids I and II. Handbook of experimental pharmacology. Berlin: Springer-Verlag, 1993; vol. 104.
Dickenson AH., (1994), Where and how do opioids act? Proceedings of the 7th World Congress on Pain. In: Gebhart GF, Hammond DL, Jensen TS, editors. Progress in pain research and management, Vol. 2. Seattle: IASP Press, 1994:525-52
Reisine T. and Bell GI., (1993), Molecular biology of opioid receptors. Trends Neurosci 1993;16:506-10.
Stoelting R. K., Hillier S. C., (2005), Pharmacology and Physiology in Anesthetic Practice, 4th ed, Lippincott Williams & Wilkins,US
09 3 / 2014
Well here we go. Let’s talk about the big one; the prescription opioid which is most commonly abused…methadone!
Before I go into the nitty gritty of it, how about a quick history lesson: methadone or Dolophine was a purely synthetic opioid that was first synthesised back in 1937 by German scientists who were looking for an alternative to morphine which would help alleviate pain but also boost the morale of soldiers but instead, the drug they invented; polamidon, did indeed help in relieve pain but also came with making the person who just took the drug feel sluggish, apathetic and insanely drowsy leading the Germans to abandon the drug’s use in warfare. 8 years later after the war ended, the US confiscated the patents filed by the Germans and then in 1947 Eli Lilly and Company introduced the drug in the US with the trade name Dolophine.
Methadone is another of those interesting drugs which can’t just have 1 molecule acting on 1 receptor to produce a certain response but noooo methadone had to be all special and have 2 enatiomers; dextro and levo which act on separate receptors…but before I go into that lets discuss its synthesis.
Methadone has quite a complex synthesis pathway and is one that has been refined over time:
Whilst this may look pretty complicated, let’s break it down shall we? The image shows 5 major steps and the production of 9 intermediaries. Intermediary 3 produced at the end of step (1) is subjected to 2 branched reactions with methadone being produced at the end of step (3) or step (5) depending on what route is taken. Steps (2) and (3) represent the old method whilst (4) and (5) for the newer one. Right off the bat we see that step (4) is highly useful because it eliminates the usage of intermediary 4, 6 and 7 – less intermediaries = less steps = less materials used = less wastage + less time (win-win-win-win). Additional to the less wastage, it was found that by using the method in steps (4) and (5) yielded a greater ratio of the required product (A 3:2 ratio of the desired product; up from 1:1). Mad props to Cusic (1949) for discovering the method and Barnett (1977) for refining and patenting it.
Once synthesised, the end product is still a mixture of both levo and dextro enantiomers (in a 3:2 ratio) but the levo enantiomer is much more useful (will discuss in a bit) and so the end product is purified further by either d-(+) - tartaric acid (Larsen etal., 1948) or more recently (-)-3-bromo camphor-sulfonic ammonium (Lemberg etal., 2006). However, this is becoming rarer as it’s quite costly to purify the enantiomers and just to clarify, I will not go into optical resolution in this blog…
Levo vs Dextro pharmacodynamics
As I said earlier, methadone comes in 2 forms: levomethadone and dextromethadone with both of them acting using slightly different mechanisms of action:
- Dextromethadone – Glutamate NMDA receptor antagonist
- Levomethadone - μ-opioid receptor agonist, weak glutamate NMDA receptor antagonist, nicotinic receptor antagonist
So, as you can see, the levo version totally kicks the dextro’s ass in terms of potency and effects; 50 times more potent (Buschmann, (2002). I realise that I have not gone into proper depth of the deeper mechanisms of action for any of the opioids I have discussed previously but fear not for next week I shall go into depth of how opioid receptors, NMDA receptors and nicotinic acetylcholine receptors work.
Methadone has a range of administrative routes such as oral, sublingual, IV or rectal with each having its own effect. The most common route is oral as its uptake is variable but is usually high (35-100%) unlike other opioids mainly due to methadone being highly lipophilic in nature. Absorption of methadone takes about 0.7 hours (Wolff et al., 1977) and leads to a whopping bioavailability of 90% BUT, due to methadone’s nature, has a very high protein and tissue binding leading to only 7-12% of the drug remaining active at one time. The high binding also means that the drug stays in the system for a prolonged period of time; about 36 hours (for comparison, heroin and morphine have half lives of 2 and 4 hours respectively)…
Methadone is then transported to the hepatic portal vein and into the liver where it is metabolised by the cytochrome p450 enzyme CYP3A4. It has also been found that the enzymes CYP2B6, CYPC19, CYP2D6 and CYP2C9 are also involved in the metabolism of methadone. (Ferrari et al., 2004)
Methadone is then metabolized to two primary metabolites, 2-ethylidene-1,5 dimethyl-3,3-diphenylpurrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenylpyrroline (EMDP). The metabolites themselves however do not have any pharmacological activity (Ferrari et al., 2004). Thereafter, the drugs along with their metabolites are subjected to renal clearance with only about 1-3% of the dose leaving the urine in its unchanged form.
Methadone, much like its brother opioids, holds a legal status of being a class A scheduled drug (without a prescription) and offers up to 7 years in prison an unlimited fine or both for possession and up to life in prison, an unlimited fine or both for distribution.
Legal mumbo jumbo from https://www.gov.uk/penalties-drug-possession-dealing
Barnett C., Modification of Methadone Synthesis Process Step, US Pat. 4,048,211
Buschmann H., (2002). Analgesics: From Chemistry and Pharmacology to Clinical Application. Wiley-VCH. p. 196.
Cusic J. W., (1949) An Improvement on the Process for Making Amidone, JACS 71, 3546
Ferrari A, Coccia CP, Bertolini A, Sternieri E., (2004) Methadone—metabolism, pharmacokinetics and interactions. Pharmacol Res. 2004 Dec;50(6):551-9. Review. PubMed PMID: 15501692.
Larsen A. A., Tullar B. F., Elpern B., Buck J. S., (1948), The resolution of Methadone and related Compounds, Journal of American Chemical Society 70: 4194 -4197,
Lemberg K , Kontinen VK, Viljakka K, Kylanlahti I, Yli-Kauhaluoma J, Kalso E., (2006) Morphine, oxycodone, Methadone and its Enantiomers in different Models of nociception in the rat, Anesth Analg 102 :1768-1774.
02 3 / 2014
Oxycodone aka oxy is one of those drugs that are not that common in the UK but more so in the USA mainly due to availability and preference. Now I don’t have any peer reviewed sources but street wise methadone or even straight heroin are considered as being better alternatives to oxy primarily due to price; heroin is miles cheaper than oxy but oxy gives a more ‘euphoric’ high and comes in a convenient pill. One dude I know described it to me as such: taking heroin is like napping in clouds whilst oxy is like wearing a onesie made of clouds then being continuously hugged by it…
Unlike codeine which is a naturally derived opiate, oxy is a semisynthetic opioid extracted from thebaine; another form of naturally occurring opiates derived from opium poppies. Not sure if I mentioned this earlier or not but opium poppies are more like cocktails containing many different opiates. The poppies themselves are known as P. somniferum; the only species of Papaver used to produce opium. The cocktail contains morphine, codeine, noscapine, papaverine, and thebaine; the most abundant being morphine at about 12-17%. All of the above other than thebaine are used clinically as analgesics to reduce pain without a loss of consciousness. Thebaine on the other hand doesn’t have analgesic effects but is used to produce semisynthetic opioid morphine analogues such as oxycodone, dihydromorphenone, and hydrocodone. Now, you may ask why even use thebaine if you’ve got several other opiates that actually work…well dear reader, if utilised correctly, thebaine can be used to synthesise analogues that are far more potent than morphine. Oxy is an example of such a thing which was made in 1919 in Germany due to pharmaceutical companies trying to improve pre-existing medicines.
The synthesis is as follows:
Extracted from patent: EP2121699 B1
After being taken, oxy is metabolized by the cytochrome P450 enzymes CYP2D6 and CYP3A4 where it’s metabolised into quite a few metabolites:
(Lalovic et al., 2005)
Now, unlike morphine, which acts upon μ-opioid receptors the active metabolites of oxy then go on and act on κ-opioid receptors, present in the hypothalamus, periaqueductal gray, spinal cord and in pain neurons. When activated, it induces feelings of sedation specifically dissociative anesthetist effects. Thereafter, the metabolites are mainly excreted via the renal system and also by sweat.
Oxy is a straight up class A scheduled drug without a prescription and holds a bounty of Up to 7 years in prison, an unlimited fine or both for possession and Up to life in prison, an unlimited fine or both for dealing.
Legal bits again taken from https://www.gov.uk/penalties-drug-possession-dealing
Patent found from: http://www.google.com/patents/EP2121699B1?cl=en
Figure 1 from Lalovic B, Kharasch E, Hoffer C, Risler L, Liu Chen LY, Shen DD. Pharmacokinetics and pharmacodynamics of oral oxycodone in healthy human subjects: role of circulating active metabolites. Clin Pharmacol Ther. 2006 May;79(5):461-79. PubMed PMID: 16678548.
23 2 / 2014
Since I wanted to discuss the different types of opiates, I thought I’d talk about codeine first. Codeine is a naturally occurring opiate extracted from the opium poppy but since this is a pretty long, tedious and highly inefficient process (each opium poppy has around 3% codeine), codeine is mass produced either semi-synthetically or synthetically. The latter of which has the potential to become more common as it eliminates the poppy altogether. The new method was detailed by Magnus et al in 2009. Check it:
So, once ingested; readily by the GI tract I might add, codeine enters the body and heads on over to the liver where CYP2D6; a cytochrome P450 enzyme, converts codeine to good ol morphine via demethylation which then goes on to act upon the μ-opioid receptor - which is found in abundance in the peri aquiductal gray; a location which is predominantly used by endorphins to induce analgesia. On a side note, endorphins are about 18 to 33 times more potent than morphine (Loh et al, 1976)
BUT! Only about 5-15% of codeine goes through this route. The rest of it is subjected to other enzymes like CYP3A4 and UGT2B7 (both in the liver) which transform it into the inactive products norcodeine and a conjugate respectively:
Once all is said and done, morphine then undergoes glucuronidation and undergoes renal clearance.
Codeine’s a bit of a tricky one as the legality of it in the UK depends on it being combined with another drug like paracetamol or ibuprofen as long as its max amount doesn’t exceed 12.8 mg or 15mg in liquid form - both of which apply for over the counter only. Any higher requires a prescription but even that must be combined with another drug AND must be below 100mg… By itself it’s considered a class B drug for which the penalty is up to 5 years in prison, an unlimited fine or both for possession and up to 14 years in prison, an unlimited fine or both if you feel like producing and supplying it.
Loh HH, Tseng LF, Wei E, Li CH. beta-endorphin is a potent analgesic agent. Proc Natl Acad Sci U S A. 1976 Aug;73(8):2895-8. PubMed PMID: 8780; PubMed Central PMCID: PMC430793.
Legal bits taken from https://www.gov.uk/penalties-drug-possession-dealing
Magnus’s method of synthesis taken from https://www.chem.wisc.edu/areas/reich/syntheses/codeine-magnus.htm
16 2 / 2014
As stated in previous posts, there are many types of opioids classified into types:
- Natural opiates derived from the opium poppy e.g. codeine
- Semi-synthetic opioids – derived by modifying natural opiates e.g. oxycodone
- Fully synthetic opioids – analogues of opium e.g. methadone
- Endogenous opioids – opioids produced in the body e.g. endorphins
Whilst working to all complete the same end result; analgesia, they differ in their biochemistry – structure, mechanisms of action, pharmacodynamics pharmacokinetics etc. Since there are a few drugs to discuss I decided to summarise them in to a neat table:
You may notice that I didn’t include endogenous opioids mainly because they’re not drugs of abuse…However, I will include them next week as a way of comparing the drugs of abuse to endogenous molecules.
16 2 / 2014
So, my research buddy very generously allowed me to take opioids as my main research topic from the 3 main categories of drug types of abuse (opioids, CNS depressants and stimulants). I’ll be dividing my blogging into parts during this research and aim to cover (hopefully in this order):
- Mechanism of action
- Analytical techniques to test for the drug
- Legality/statistics and reasons for abuse
And on with the show!
05 2 / 2014
Well that’s the whole what question sorted out (what drugs are abused) but what about the why? Why are these drugs abused? Well my fellow reader, the answer is pretty straightforward really as you shall now see
Opioids – Mainly abused by heroin addicts or addicts trying to recover from addiction whilst trying to minimise withdrawal symptoms. Abuse of opioids such as methadone occurs because the effects of methadone are pretty weak sauce when compared to a full on heroin dose. Also, opioids are a class of analgesics (pain killers) which have a tendency of creating a feeling of immense euphoria or a ‘high’ in the users leading to its constant abuse. I’ll be going into detail about the mechanisms of reward and addiction at a later date. In somewhat related news, a study conducted in the Netherlands by van den Brink etal found that patients exhibited a marginally better response to heroin withdrawal when methadone was combined with a controlled and supervised does of heroin when compared with methadone alone. He states that supervised co-prescription of heroin is feasible, more effective than and probably as safe as methadone alone in reducing the many physical, mental, and social problems of treatment resistant heroin addicts.
CNS Depressants – These drugs are primarily prescribed to people who suffer from conditions such as anxiety, panic attacks, insomnia etc. They are abused simply because they make people not care as much by sedating themselves and making them feel like every little thing is gonna be alright thus allowing them to mask their problems.
Stimulants – Amphetamines are a classic example of prescription abused drugs such as Adderall; not so much in the UK when compared to the USA. The reason why they are abused is that the users say that it gives them an edge both mentally and physically; a performance and cognitive enhancer. It’s mainly prescribed for sufferers of attention deficit hyperactivity disorder (ADHD) but is commonly abused by otherwise ‘normal’ people. To put things into perspective, have you seen the movie limitless starring Bradley Cooper? Yeah, that film was described as being a 2 hour long Adderall advert…
Others – ones that don’t fit into the other categories such as DMX (Dextromethorphan) which acts as a hallucinogen. It’s abused because it’s pretty simple to pick up from any pharmacy (again, more common the USA), and provides the user with an easy means of trippin balls. Oh, and Viagra also fits into this category but I’ll let your imagination decide why that’s abused :|
Van den Brink W, Hendriks VM, Blanken P, Koeter MW, van Zwieten BJ, van Ree
JM. Medical prescription of heroin to treatment resistant heroin addicts: two randomised controlled trials. BMJ. 2003 Aug 9; 327(7410):310. Erratum in: BMJ. 2003 Sep 27; 3217(7417):724. PubMed PMID: 12907482; PubMed Central PMCID: PMC169643.
05 2 / 2014
So I spoke with my mate down in Boots about the drugs most commonly abused by folks in the UK and he gave me the following list:
(The first name is the drug name, the second name is the trade name and the drug class is given in brackets)
- Methadone - Dolophine (Synthetic opioid)
- Buprenorphine - Subutex (Semi synthetic opioid)
- Codeine - (Opiate)
- Codeine phosphate - Galcodine (Opiate)
- Diazepam - Valium (Benzodiazepine)
- Temazepam - Restoril (Benzodiazepine)
Common prescription drugs abused in the USA:
- Codeine - (Opiate)
- Oxycodone - OxyContin (Semi synthetic opioid)
- Methadone - Dolophine (Synthetic opioid)
- Alprazolam – Xanax (Benzodiazepine)
- Amobarbital - Amytal (Barbiturate)
- Adderall – mixed amphetamines (Stimulant)
- Dextromethorphan DXM – Various cough syrups e.g. Robitussin or NyQuil. Antitussive (cough suppressant) in normal doses but excess leads to dissociative hallucinogenic effects.
Note: Opiates are based on natural narcotic opioid alkaloids derived from the opium poppy e.g. Morphine, Codeine, Thebaine, papaverine etc. whilst Opioids are analogues (structurally similar molecules) of morphine and are either synthetic or semi synthetic e.g. Hydrocodone Oxycodone, Diacetylmorphine (heroin - semi synthetic).
Generally, people refer to both opioids and opiates as opioids - used as a blanket term because they all act on the opioid receptors; more on receptors later on!
As stated in my blog post last week, most or if not all of the drugs most commonly abused fall under one of the 4 categories: Opioids, Central Nervous System (CNS) Depressants, Stimulants or Others. This is pretty much the same for both the UK and the USA but studies have found that CNS depressants (benzodiazepines/barbiturates) and stimulants (Amphetamines) are far more common in the USA; specifically within colleges and other educational institutions (McCabe etal, 2004).
McCabe, S. E., Knight, J. R., Teter, C. J. and Wechsler, H. (2005), Non-medical use of prescription stimulants among US college students: prevalence and correlates from a national survey. Addiction, 100: 96–106. doi: 10.1111/j.1360-0443.2005.00944.x