Salicylates

The first group of non narcotics we’re going to look at are salicylates.  Notice the four therapeutic properties of them.

1. Analgesia: It’s meant for mild to moderate pain (headache, painful periods, muscle pain)
2. Antipyretic: It lowers febrile (body) temperature but only if it’s elevated.  It won’t lower the temperature if it’s at a normal temperature.
3. Anti-inflammatory: Decreases inflammation, such as for rheumatoid arthritis, an autoimmune disease that causes inflammation in the joints. (Unlike osteoarthritis which occurs from wear and tear and not inflammation so treatment is different)
4. Anti-platelet*: A very specific property for acetylsalicylate (aspirin) only. This is used when we don’t want the platelets to be as functional and stick as well to cause clotting.  It’s not an anti-coagulant but an anti-platelet effect.  Coagulation causes a fibrin net to form, but an anti-platelet agent makes it more difficult for the fibrin to stick to the fibrin net.

Aspirin is used during a transient ischemic attack (TIA). A TIA is like a stroke, they lose sensation, feeling, maybe they can’t talk, but the difference is that it’s temporary.  This occurs due to lack of oxygen versus the oxygen demand and the oxygenation comes back.

Post MIA: If the person has had a heart attack, we give them aspirin.  We find that aspirin decreases the probability of having a second heart attack.  If the person is having a heart attack and they’re home, they are told to take aspirin.

Cardiac valve replacement: If a person has had a cardiac valve replaced, and has a prosthetic valve (not an animal valve), a plastic-like valve, what tends to happen is that blood tends to coagulate there and if this clot keeps growing, it eventually breaks off, goes into the coronary artery and cause a heart attack, or the carotid artery and cause a stroke.

Acetylsalicylate Dosage

Aspirin (acetylsalicylate) has a very unique, ultra-low dose.  A person is told to not take more than 1 aspirin a day.  If you go to higher doses, it counteracts the anti-platelet effect.

What’s the definition of a low-dose aspirin? There’s two strengths of aspirin.  Most go with the low dose, some go with the high dose.  The low strength dose is 81mg.  The other is 325mg.  What’s another term for that 81mg aspirin?  Baby aspirin.  Historically we used to give it to children, but today we will NEVER give a child aspirin otherwise they’ll develop Reye’s syndrome (inflammation of the brain and potentially fatal).  We eventually saw a correlation that the use of aspirin in children who had chicken pox (varicella virus) had a very high risk of Reye’s Syndrome.  Then the analysis went further and saw that ANY viral infection and aspirin leads to a high risk of Reye’s Syndrome.

Why did we ever give aspirin to a child?  Fever. And the most common cause of a fever was a viral infection.  If it was a bacterial infection, the risk wasn’t there, but usually you don’t know if the cause is viral or bacterial.  The 325mg is called the adult-strength aspirin.  People taking it for anti-platelet effects only need the low-dose.

GI Effects

Salicylates GI effects include nausea/vomiting and there’s a very high risk of ulcers.  It’s irritating to the GI so if a person has a history of ulcers, we have a problem.  But not necessarily always, because we’ve talked about enteric coatings.  If they have a high risk of stomach ulcers but not gastric, they could take enteric-coated salicylates, especially for aspirin.

Toxicities

The first warning sign that someones blood levels are getting too high on salicylates is tinnitus.   This means they’re potentially toxic or on the verge of toxicity.  If they don’t heed that warning they can go into metabolic acidosis which can lead to dehydration which could potentially be fatal.

Properties

Uricosuric: Salicylates can have uricosuric properties.  Uricosuric means it pushes uric acid into the urine.  This is especially useful when someone has a gout attack (when the uric acid crystallizes in the joint they have gout).  Low doses of salicylates have the OPPOSITE effect meaning they retain uric acid.  When someone has anti-platelet aspirin (which causes them to retain uric acid) and they are prone to gout, then we have a problem.

Hypersensitivity:  Salicylates for some reason have a higher incidence of allergies in women and in asthmatics.  There is also the risk of cross sensitivity with some NSAIDs (naproxen, aleve, tylenol, etc).

Doses

Doses can be quite low for the anti-platelet effect, or it could be quite high when used for anti-inflammatory effects.  How high could the high dose go?  Just short of tinnitus, the sky is the limit, which could potentially be something like 1.5 grams for a dose.

Other Uses

Other potential uses for the salicylates are topical. It’s keratolytic and a high concentration of it is used topically for warts.

Another topical use is as a counter-irritant for muscle pain.  When you use a sports creme, you almost immediately get a sensation on the skin of warmth, heat, and burning.  Blood vessels are dilating and providing this heat.  When you’re working out and you switch from aerobic to anaerobic metabolism, the glucose being metabolized for energy cannot enter the krebs cycle without oxygen and you get a build up of lactic acid.  This build up of lactic acid causes pain so you have to get the sports creme on before the pain starts.  This dilates the blood vessels to hopefully carry the lactic acid out and into the kidneys.

All of these topical salicylates are toxic if ingested orally because the doses are extremely high.

Let’s highlight these drugs:

All salicylates have 3 properties (analgesic, antipyretic, anti-inflammatory) but acetylsalicylate has 4 properties (+anti-platelet) in low doses.  Enteric coated acetylsalicylate also has 4 properties because the coating doesn’t change anything.

Salsalate (Disalcid) is used for RA and the advantage is that it has a low incidence of GI irritation.

Methylsalicylate is the one in sports cremes that goes on your skin and has a minty odor to it.

ASA (short for Aspirin) has no liquid form because manufacturers can’t make it last more than 3 days.  If you want a liquid form you must mix it with alka-seltzer to dissolve.  There’s alka-seltzer in cold products, tylenol products, so be careful of that.