Dopa-Amine
Greenlighter
- Joined
- Jan 31, 2011
- Messages
- 33
Hi all,
I am a long-term lurker of these forums although I dont come in as much as I would like to. Despite my recent registration, I would like to suggest if we could make a thread with regards to Warfarin and contraindicated psychotropics.
For those who don't know, warfarin is a widely prescribed anticoagulant aka blood thinner. It is prescribed for many indications, mostly those related with the clotting of the blood. It relies upon inhibiting an enzyme in the liver which recycles Vitamin K, which is a precursor to several clotting factors. In other words, it is a vitamin K antagonist.
Warfarin leads to the delaying of clotting hence decreasing the chances of developing a clot in a vein. Most people on warfarin are people who suffer from hypercoagulability disorders in which their blood will clot too much, a clot in the blood can break away from its formation site and travel the bloodstream to block the arteries in the lungs or even the heart, producing anywhere from infarction (death of tissue) to sudden death.
Warfarin's effect on the blood needs to be frequently monitored via testing how long it takes for the blood to clot (INR - International Normalised Ratio). Unfortunately, the INR has a very narrow therapeutical margin and many medications affect the INR. Too high an INR, and chances of bleeding anywhere in the body (included brain and vital organs) increases dramatically, too low an INR and chances of abnormal clotting (in predisposed individuals) shoots up. Unfortunately, most people on warfarin have to be on it for the rest of their lives which means making quite some lifestyle changes (e.g no smoking).
The aim of this thread would be to provide some guidelines or information as to psychotropics that could affect the INR, especially recreational drugs. This does not need to be documented per se in the literature, but it can be speculation or educated guesses (hence why I am putting it up in this sub-forum). I have been using warfarin for over 4 months now (have two left but it could be for the rest of my life) and I have researched extensively medications that will or will not affect the INR. Recreational drugs are not covered and many of the listed interactions are speculated.
Warfarin metabolism is as follows:
The anticoagulant drug warfarin occurs as a pair of enantiomers that are differentially metabolized by human cytochromes P450 (CYP). R-warfarin is metabolized primarily by CYP1A2 to 6- and 8-hydroxywarfarin, by CYP3A4 to 10-hydroxywarfarin, and by carbonyl reductases to diastereoisomeric alcohols. S-warfarin is metabolized primarily by CYP2C9 to 7-hydroxywarfarin. Potential warfarin-drug interactions could occur with any of a very wide range of drugs that are metabolized by these P450s, and a number of such interactions have been reported. The efficacy of warfarin is affected primarily when metabolism of S-warfarin is altered.
Pharmacol Ther. 1997;73(1):67-74.
Human P450 metabolism of warfarin.
Other interactions can be due to substances affecting platetet aggregation (e.g ginger or garlic) as well as due to unexplained reasons which increases the risk of altering the INR when taking a new exogenous substance.
There are quite some interactions recorded in the literature, with an ample variety of medicines which affect INR. However, the fact that a medication is not included in the list of interactions does NOT imply that it does not interact with warfarin, namely recreational drugs.
It is thus that I am starting this thread so as to offer a reference for those who use drugs (medically and recreationally) and are unfortunate to use warfarin. A quick google search yields 31 million prescriptions written for the year 2004 according to the FDA, which means that there is quite some population out there who will be using warfarin and psychotropics concomitantly, most without knowing the real danger of such.
I would like to start offering some of my experiences with certain medications and some questions which would feed a potential debate and long thread. I would, however, like to know if this thread could go anywhere, as in, receive enough responses to make it worth the time (whether in this sub-forum or elsewhere in Bluelight). I have not seen a thread covering this topic in depth hence why I enquire and try to promote the covering of such an interesting topic, which would serve as a quick reference to, I am sure, hundreds of people.
Many thanks.
I am a long-term lurker of these forums although I dont come in as much as I would like to. Despite my recent registration, I would like to suggest if we could make a thread with regards to Warfarin and contraindicated psychotropics.
For those who don't know, warfarin is a widely prescribed anticoagulant aka blood thinner. It is prescribed for many indications, mostly those related with the clotting of the blood. It relies upon inhibiting an enzyme in the liver which recycles Vitamin K, which is a precursor to several clotting factors. In other words, it is a vitamin K antagonist.
Warfarin leads to the delaying of clotting hence decreasing the chances of developing a clot in a vein. Most people on warfarin are people who suffer from hypercoagulability disorders in which their blood will clot too much, a clot in the blood can break away from its formation site and travel the bloodstream to block the arteries in the lungs or even the heart, producing anywhere from infarction (death of tissue) to sudden death.
Warfarin's effect on the blood needs to be frequently monitored via testing how long it takes for the blood to clot (INR - International Normalised Ratio). Unfortunately, the INR has a very narrow therapeutical margin and many medications affect the INR. Too high an INR, and chances of bleeding anywhere in the body (included brain and vital organs) increases dramatically, too low an INR and chances of abnormal clotting (in predisposed individuals) shoots up. Unfortunately, most people on warfarin have to be on it for the rest of their lives which means making quite some lifestyle changes (e.g no smoking).
The aim of this thread would be to provide some guidelines or information as to psychotropics that could affect the INR, especially recreational drugs. This does not need to be documented per se in the literature, but it can be speculation or educated guesses (hence why I am putting it up in this sub-forum). I have been using warfarin for over 4 months now (have two left but it could be for the rest of my life) and I have researched extensively medications that will or will not affect the INR. Recreational drugs are not covered and many of the listed interactions are speculated.
Warfarin metabolism is as follows:
The anticoagulant drug warfarin occurs as a pair of enantiomers that are differentially metabolized by human cytochromes P450 (CYP). R-warfarin is metabolized primarily by CYP1A2 to 6- and 8-hydroxywarfarin, by CYP3A4 to 10-hydroxywarfarin, and by carbonyl reductases to diastereoisomeric alcohols. S-warfarin is metabolized primarily by CYP2C9 to 7-hydroxywarfarin. Potential warfarin-drug interactions could occur with any of a very wide range of drugs that are metabolized by these P450s, and a number of such interactions have been reported. The efficacy of warfarin is affected primarily when metabolism of S-warfarin is altered.
Pharmacol Ther. 1997;73(1):67-74.
Human P450 metabolism of warfarin.
Other interactions can be due to substances affecting platetet aggregation (e.g ginger or garlic) as well as due to unexplained reasons which increases the risk of altering the INR when taking a new exogenous substance.
There are quite some interactions recorded in the literature, with an ample variety of medicines which affect INR. However, the fact that a medication is not included in the list of interactions does NOT imply that it does not interact with warfarin, namely recreational drugs.
It is thus that I am starting this thread so as to offer a reference for those who use drugs (medically and recreationally) and are unfortunate to use warfarin. A quick google search yields 31 million prescriptions written for the year 2004 according to the FDA, which means that there is quite some population out there who will be using warfarin and psychotropics concomitantly, most without knowing the real danger of such.
I would like to start offering some of my experiences with certain medications and some questions which would feed a potential debate and long thread. I would, however, like to know if this thread could go anywhere, as in, receive enough responses to make it worth the time (whether in this sub-forum or elsewhere in Bluelight). I have not seen a thread covering this topic in depth hence why I enquire and try to promote the covering of such an interesting topic, which would serve as a quick reference to, I am sure, hundreds of people.
Many thanks.
