Welcome to UH EMS-I’s Pharmacy Phriday. In our last installment, we reviewed the use of aspirin (ASA) within the Acute Coronary Syndrome Protocol. In this session, we will look at another oral antiplatelet medication, ticagrelor, used in a confirmed STEMI.
When a patient has a heart attack, one of the treatment goals is to reduce clotting and the size of the infarcted area. Blood thinners are often a component of the treatment in meeting those goals. Blood thinners are quite common and are used in acute events as well as maintenance and prevention of thrombolytic events.
Blood thinners don’t actually thin blood. They work by interfering with the natural processes that cause blood to clot, either by preventing platelets from sticking together or by slowing down the clotting process. Medicines that prevent platelet aggregation and the formation of clots, like ASA and ticagrelor, are referred to as antiplatelets. Medicines that interfere with or slow down the clotting process are called anticoagulants. An example of an anticoagulant is heparin, which we will review in our next installment.
In general, antiplatelets interfere with the binding of platelets, or the process that starts the formation of blood clots. Various antiplatelets have various pharmacologic actions, but all antiplatelet drugs inhibit platelet activation and aggregation.
UH EMS-I’s STEMI protocol reflects an approach to treatment often referred to as dual antiplatelet therapy (DAPT). This approach includes using ASA, the most common antiplatelet medication, plus ticagrelor, a P2Y12 inhibitor. Ticagrelor, our focus in this installment, blocks certain receptor sites and diminishes platelet activation by a compound in the blood clotting process called adenosine diphosphate (ADP). This approach addresses platelet inhibition from another aspect and meets the goal of the dual therapy theory.
One of the contraindications for administering ticagrelor is if the patient is currently taking an antiplatelet medication at home. Within the protocol, common antiplatelet medications have been listed for our reference. Some of the more common medications in this group include Plavix, Effient, and Ticlid. Other contraindications include bleeding, intracranial hemorrhage, liver failure, a patient greater than 80 years of age, cocaine or stimulant-induced STEMIs, or the pediatric patient.
To avoid inappropriate administrations, a STEMI checklist is also a part of the protocol and should be reviewed before administering ticagrelor or heparin. Items included in the checklist are:
- No sharp ripping/tearing chest or back pain.
- No altered mental status
- No known bleeds or concern of bleeding (i.e., GI bleeds, vomiting blood, blood in urine, etc.)
- No trauma or CPR
- No severe headache
- If STEMI mimickers are present, must consult Medical Direction.
The UH protocol allows the administration of ticagrelor orally for patients with a confirmed STEMI. When in doubt about the presence of a STEMI or any of the contraindications for the use of the medication, it is advisable to contact Medical Direction for advice.
The dosing of ticagrelor is 180 mg (two 90 mg tablets), given once, which should be chewed, and then swallowed. Literature suggests that having the patient chew the tablets may accelerate the onset of action of the antiplatelet effects of the medication.
Common side effects of ticagrelor listed include bleeding concerns as well as respiratory distress and shortness of breath. Be sure to monitor your patient for these serious side effects.
A final consideration noted in the protocols related to the administration of ticagrelor that we should highlight is the use of opiate pain medications at the same time. It is documented in numerous sources that ticagrelor’s absorption and effectiveness can be reduced when also administering an opiate for pain, primarily due to slowed gastric emptying. Co-administration of ticagrelor and fentanyl is also documented to increase the effects of the fentanyl possibly causing increased sedation and respiratory depression. For some of these reasons, the routine use of an opiate when using ticagrelor is discouraged.
Check in next week for our installment discussing the use of heparin, our anticoagulant used for STEMI patients. Till then, be safe!