Hey, welcome to chapter four aminoglycosides I. I'm sure I'll do another video about aminoglycosides, but I just want to introduce the drugs themselves.
Amikacin which is brand Amikin,
gentamicin (Garamycin),
neomycin
as part of Neosporin but also as part of some other combination drugs
usually for topical things, and then tobramycin
(Tobi or Tobrex).
Common to the class since we're using drugs that are all in the same class is
ototoxicity,
nephrotoxicity, and with that nephrotoxicity we need to reduce dose based on renal function.
Note, however, that we have three different stems in the same drug class.
'-kacin' is
maybe the exception, but the '-mycin' and the '-micin',
you can't use these for
identifying the drug class that the particular antibiotic belongs to.
Let's do our practice question. Providers worried about aminoglycoside resistance, which would be the best to provide the patient?
Select all that apply.
When we're talking about these, the first things that come to mind with amikacin is that it does have the least resistance.
Gentamicin is relatively cheap.
Neomycin is the most
toxic so we only really see topical forms, and then tobramycin has an inhalable form which is a little bit unusual.
They're working on getting amikacin in an inhalable form, there's like a liposomal form that
they're working on but I haven't seen that it's come out yet.
And then of course amikacin has the least resistance.
Let me convert it to the drug names. As we'll go to question two, the four drug names amikacin,
gentamicin, neomycin, tobramycin, and the way that I remember that amikacin
has the least issues with the resistance
or works against multi-drug resistance is
the word 'ami'. You think like monami, 'my friend' in french is your friend, so I think,
well, if I had a multi drug resistant organism, then amikacin would sure as heck be my friend,
but that's how I would remember it.
Let's go to practice question number three, let's make B) correct.
'An elderly patient has kidney dysfunction as demonstrated by poor urine output and creatinine clearance, and
creatinine clearance is a way of measuring the GFR, the glomerular filtration rate.
Which medication would need a dosage reduction because of nephrotoxicity?'
The answer is all four, sort of.
Neomycin doesn't really have any parenteral forms,
so you wouldn't really
have this issue, but it's because it was so nephrotoxic that you only see topical forms. The way that I remember
nephrotoxicity and
ototoxicity to the class because I can put all four of these in my head as soon as I hear neomycin I immediately think of
its friends amikacin, gentamicin, and tobramycin.
The first two letters in neomycin are N-E for nephrotoxic, and the next letter is O for ototoxic
That's how I remember those two are part of the class those two toxicities.
Let's again make C) correct. 'Which aminoglycoside is so nephrotoxic, and so ototoxic, that it only comes in topical forms?'
Neomycin.
If it were to have you know IV forms it would be terribly nephrotoxic and ototoxic
so we only see the topical forms. A lot of times we see them in combination.
Neosporin is probably the best answer or best example. We have Neosporin that has neomycin, polymyxin B and bacitracin.
And then let's make D) correct 'Which aminoglycoside has an inhalable form for cystic fibrosis?'
Interestingly enoug,h tobramycin has this Tobi inhalation solution or Tobi
Podhaler. The way that I remember that is that there's a B-R in tobramycin so I think of it
as the first two letters in breathe.
Question number six, we'll make D) correct
but select all that apply: 'A patient complains of ringing in the ears, which
medication could have caused this?' I put that all four could have. Again that
tinnitus or
ototoxicity is part of what this class does as its adverse effect.
I did put the neomycin would cause that if it had a parenteral form, but amikacin,
gentamicin, neomycin, tobramycin all can cause this ototoxicity.
So, just to review real quick,
Amikacin is the one with the least resistance and they are working on an inhalable form but I don't know that it's out now.
Gentamicin,
again, is one of the cheapest ones I think of gent- and cent
so you know one penny as being relatively inexpensive, but
when we talk about, you know, as a class, it's going to have the ototoxicity, it's going to have the nephrotoxicity.
Neomycin is special because it's really so toxic that we have to use topical forms and to use that N-E-O to remember
nephrotoxic and ototoxic. Tobramycin, remember the B-R for breathe because it has that
inhalable form for cystic fibrosis.
With all these toxicities, maybe you have children and you remember getting
gentamicin or tobramycin for the child's eyes for pinkeye.
There's very little systemic absorption when you have these drugs when you use them topically, so
gentamicin and tobramycin are perfectly safe to use with a child when you're using it for pink eye or conjunctivitis.