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patients with alcoholism require increased amounts of local anaesthesia for 2 reasons
1. cns effects of alcohol
2.liver enzyme induction
In patiens with mild to moderate alcoholic liver disease there may be significant enzyme induction is likely to have occured. This leads to increased tolerance of local anaesthesia. for that matter tolerance also develops to many drugs some being sedatives , hypnotics , general anesthetics
I personally do NOT see any reason for the LA not to work after overnight alcoholic binge....
The success of LA is actually subjective...the patient 'complains' of 'pain' and we all know the variablility of anything subjective.
I am not suggesting that the patient is actually imagining but just trying to put forth an explanation since I could not come across any solid reference till now.
I guess the best place to search for an answer would be acute maxillofacial trauma texts..which might probably explain these issues since alcoholic binge is a common cause of the 'macho man fights' and nasal # or accidents.
Joined: Jan 25, 2006 Posts: 295 Location: new delhi
Posted: Fri Mar 17, 2006 2:33 pm Post subject:
it's not a subjective sign. it's very much true that the la does't work in such cases. i was told about this by one of my lecturer's in clinics when it happened with a patient. but i am sorry to say, i didn't asked for the explanation at that time. i have searched through a great number of journal also along with the standard text books but am unable to get the correct explanation though one or two articles in journal of pharmacology have explained that the biotransformation . according to one article
"Although liver is the main site of drug metabolism, it has recently become clear that intestinal drug metabolism has a large influence on presystemic or first-pass drug biotransformation (Hall et al. 1999). However, both the protein level and catalytic activity of drug-metabolising enzymes in the small intestine are generally lower than those in the liver."
thus i think the alcohol is probably desrupting the protien and drug metabolizing enzymes due to it's dehydrating effect on the proteins and enzymes needed for first pass drug metabolism. thus preventing the of l.a to act
though i haven't got the accurate answer till now. but i am trying to get one and as soon as i get it, i will post.
but this definately is a very good question _________________ Oh God grant me the serenity
to accept the things i cannot change,
courage to change the things i can,
and the wisdom to know the difference
Cigarettes and alcohol affect your body just as strongly and sometimes more than any of the medically prescribed drugs you may be taking. Because of their various effects on your lungs, heart, liver and blood, to name a few, cigarette and alcohol consumption can change the way an anesthetic drug will work during surgery, so it is crucial to let your anesthesia provider know about your consumption of these substances. This is also true for so-called street drugs-marijuana, cocaine, amphetamines and the rest. People are somewhat reluctant to discuss things, but it is worth remembering that such discussions are entirely confidential between you and your doctor. The anesthesia provider’s only interest in these subjects is in learning enough about your physical condition to provide you with the safest anesthetic possible.
* Excessive alcohol consumption can impair coagulation * _________________ Smile becoz God gave Human this beautiful gift - A Smile....I sometimes wonder do animals have this beautiful gift of smiling???
Joined: Jan 25, 2006 Posts: 295 Location: new delhi
Posted: Fri Mar 17, 2006 5:33 pm Post subject: interaction of local anesthetic with alcohol
the main reason for failure of local anesthetic to act is due to a enzyme called CYP
Cytochrome P450 (CYP) Isoenzymes: The name Cytochrome P450 comes from the wavelength of light (450n.m.) that is absorbed by these isoenzymes.CYP isoenzymes are responsible for oxidative metabolism (Phase I) of many drugs, steroids and carcinogens. CYP isoenzymes are a group of heme-containing enzymes embedded primarily in the lipid bi-layer of the endoplastic reticulum of hepatocytes (liver cells). CYP metabolism also occurs - to a lesser extent -in the small intestine, kidney, lung and brain. More than thirty (30) CYP human isoenzymes have been identified, CYP3A4,CYPIA and CYP3A4 being some of them.
now coming over to local anesthetic:
Lidocaine is widely used as a local anesthetic and antiarrhythmic drug. It undergoes extensive first-pass metabolism after oral administration i.e of 35; has Tmax(h) of < 1, T1/2 (h) of < 2-3 with metabolic enzymes called CYPIA and CYP3A4 and active metabolite called MEGX i.e monoethylglycinexylidide and 3-hydroxylidocaine The principal metabolic pathway of lidocaine in humans is oxidative N-deethylation to MEGX while hydroxylation of the aromatic ring to 3-OH-lidocaine is a minor metabolic pathway. The formation of MEGX is catalyzed mainly by CYP3A4.
now this same CYP i.e cytochrome P450 enzyme is also responsible for metabolism of alcohol. as a result of competition for CYP between the alcohol and the local anesthetic, the anesthsia's metabolism is reduced, and the production of metabolites as well as their excretion declines, resulting in higher medication levels in the body. _________________ Oh God grant me the serenity
to accept the things i cannot change,
courage to change the things i can,
and the wisdom to know the difference
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