Penicillin desensitization represents a last-line option for patients with no alternative therapies, where the benefits of this intensive process must outweigh the potential harm from drug exposure. The goal is to establish a temporary state of tolerance to the drug. Pharmacist play an important role in this process.
Good morning rookies i want to talk to you today about a very interesting case i had this morning um i was called i’m in a clinical office so i’m a clinical pharmacist today and a provider called me about a 20 year old pregnant female with latent syphilis and she’s about 17 weeks pregnant and she has latent syphilis and the treatment of choice for latin syphilis
Is penicillin uh bends within 2.4 million units i am once or in this patient’s case she’s going to get it for three doses but she has a history of severe allergy reactions to penicillin um she’s 20 years old now and when she was eight years old she reports having she reported having swelling in the throat from from from one dose of amoxicillin and they really want
Her to have this penicillin for her um safety she needs to get better right and also for the safety of her baby when she’s born so they wanted to uh the doctor was inquiring about penicillin desensitization so penicillin desensitization is when you administer several increasingly um several small but increasingly higher doses of penicillin to get the patient
Desensitized kind of used to it right um and if the patient tolerates that then they go ahead and give the real dose for the penicillin treatment 2.4 million units so um i told the doctor no problem we have a penicillin desensitization protocol and my job today will be to follow through and compound all those tiny little doses of penicillin that the patient is
Going to use um so the protocol starts by giving 0.00025 units of penicillin then multiplied by about 10 and give 0.0025 actually i have it written down here so the we’re going to start with 0.00025 units then we’re going to go at 10 times that which is 0.0025 years and then multiply that by 10 we’re going to give 0.025 units and then multiply that by 10 we
Give 0.25 units we get the gist and then all the way to 3 million units so it’s going to be a lot of compounding but we have to dilute the dose so much um to get that first dose and then even to get that second nose so in total i’m gonna need to make 13 bags of penicillin doses i have my um bags here it’s gonna go in dextrose uh 25 ml bag and i have a ton of
Them here about 10 bags in here i have three bags in here and i have my penis in five million units that i’m going to be um diluting to make these patients um this patient’s doses so you can see how this couldn’t happen with other pharmacists right we need to know the math we need to know how do i get zero point zero zero zero two five units out of a five million
Violent unit so i’m going to start by adding um on the file here it has instructions on how to dilute the vial i don’t know if you can see but to get a 250 000 units um concentration i need to add 18.2 units of still water to the vial so when i add 18.2 units of tear water to this vial i get and i shake it go well and reconstitute it i get a 250 000 units per ml
250 000 units per ml now how do i make 0.00025 units out of that so my protocol says i’m going to take one ml one ml out of that vial right one ml out of the 215 000 units per ml valve i take 1ml out out and i add 9 ml of water when i add 9 mls of water i get a 25 000 units per ml concentration and i’m going to take one ml out of that and add another 9 ml
Of water and i get a less concentrated solution which is 2 500 units per ml i take 100 out of that and add 90 ml of water i get 250 units per ml and i take one ml out of that i add 90 ml i get 25 units per ml i add 900 ml water out of that i get 2.5 units per ml so you can see how we get further and further and further diluted and i continue with that process
Until i get a 0.00025 units per ml i pulled up the dilutions for you guys to see i think having a visual is better than me just talking and talking and talking so i took my 5 million unit vial and i first added 18.2 ml of sterile water to get this concentration and then i took one ml of that concentration and added 90 ml of water to make a lower concentration
And i took one amount of this concentration added 90 ml of water to make that concentration and which with each nine ml of water that i add i get a smaller and smaller concentration so at the end i’m going to have all these syringes with these various sorry that’s other drugs let’s get back to penicillin so in the end i’m going to have all these syringes with all
These different concentrations so with each syringe of these concentrations i’m going to take 4 ml of each of these syringes and shoot into a 25 ml dextrose bag so by taking 4 ml of this 250 000 units per ml times 4 i’m going to make a 1 million unit bag and with this bag here with this syringe 4 ml so that is going to make a 100 000 unit bag and 4 ml of this is
Going to make a 10 000 minute bag so we are going to do that for all of these concentrations and um with this concentration here the lowest one the patient gets a zero point i think 0.1 units bag so the patient is going to get the small dose the smallest dose and then another small dose but a little bigger and then the patient is going to get bigger and bigger
And bigger doses and if they tolerate all these doses they’re ready to get the 2.4 million unit intramuscular injection of uh penicillin benzothene so if the patient tolerates all those tiny doses increasingly tiny doses then they are um ready to get the 2.4 unit im injection of penicillin benzothene so it’s going to be a fun day in the iv room making all
These and i’m just and as i’m doing this and as i’m working and i’m just happy to be part of the solution for this pregnant woman to be able to get her treatment which she wouldn’t otherwise have been able to do unless pharmacist was here so what pharmacists do is what i do is what i talk about follow me on instagram uh tic tac um contact me and any of those uh
Platforms if you have any questions any recommendations any suggestions i’m the lucky pharmacist until the next video have a great life god bless you and god protect you love you bye
Transcribed from video
What Pharmacists Do: Penicillin Desensitization By The Rookie Pharmacist
