Contraindications

[jmail]

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Ive been out of school for few years and feel like I start to forget things...
So, I was thinking of bad mistakes that can happen, and thought of contraindications..
Would you guys be interested in having a list of contraindications?
I will start, please feel free to chime in...

1) Carbapenems reduce Valproate concentration, increases seizure risk.
2) PDE inhibitors and nitrates
3) Betta blockers in heart rate below 60 (can't remember if its contraindication or just recommendation to DC betta blocker)


Nothing else comes to mind... Please help out and share what you guys remember

 

[BidingMyTime]

There are very few absolute contraindications, but many drug pairs that have to be monitored closely and/or have their dosages adjusted. That is probably why you don't remember very many absolute contraindications.

 

[HelpfulPharmer1]

My share:
If starting H Pylori therapy and have existing Statin, then, Stop Statin, wait at least 5 Half Lives, then, take H Pylori therapy.

Overall, if Clarithromycin, stop Statin.

(Simvastatin and Lovastatin: must stop. Atorvastatin, use 20 mg max. Other statin, you find out...I don't want to muddy the message with too much details.)

Why? Clarithromycin will cause overdose of statin, leading to kidney damage.
Supporting Fact here: From Clinical Pharmacology checker: this is Top Level Interaction: Clarithromycin and Simvastatin: "Do not take these drugs together. Discuss possible alternative treatment options with your prescriber. Taking these drugs together increases the risk of serious side effects that can harm your muscles and kidneys."

Friendly info: as you work retail pharmacy, you will have many patients on existing Statin for cholesterol. If they come to you with script for H Pylori, the script will often mean you give Amoxicillin and Clarithromycin and Lansoprazole. From that therapy for H Pylori, the focus is on Clarithromycin. This Clarithromycin causes overdose of Statin, very like, kidney damage will happen.

 

[npage148]

1.statins are not Renal toxic

2. The ddi is mainly mediated via first pass inhibiton (increasing relative bioavailability) so to suggest waiting 5 half lives shows a fundamental misunderstanding of pharmacokinetics of statins

 

[RxPreceptor]

I think he/she might be referring to rhabdomyolysis for the kidney damage aspect.
There is no need to "washout" a statin

 

[CetiAlphaFive]

My share:
If starting H Pylori therapy and have existing Statin, then, Stop Statin, wait at least 5 Half Lives, then, take H Pylori therapy.

Overall, if Clarithromycin, stop Statin.

(Simvastatin and Lovastatin: must stop. Atorvastatin, use 20 mg max. Other statin, you find out...I don't want to muddy the message with too much details.)

Why? Clarithromycin will cause overdose of statin, leading to kidney damage.
Supporting Fact here: From Clinical Pharmacology checker: this is Top Level Interaction: Clarithromycin and Simvastatin: "Do not take these drugs together. Discuss possible alternative treatment options with your prescriber. Taking these drugs together increases the risk of serious side effects that can harm your muscles and kidneys."

Friendly info: as you work retail pharmacy, you will have many patients on existing Statin for cholesterol. If they come to you with script for H Pylori, the script will often mean you give Amoxicillin and Clarithromycin and Lansoprazole. From that therapy for H Pylori, the focus is on Clarithromycin. This Clarithromycin causes overdose of Statin, very like, kidney damage will happen.

Please post the mechanism for renal insult as a result of statin / biaxin D/DI

 

[PolarPop]

Ive been out of school for few years and feel like I start to forget things...
So, I was thinking of bad mistakes that can happen, and thought of contraindications..
Would you guys be interested in having a list of contraindications?
I will start, please feel free to chime in...

1) Carbapenems reduce Valproate concentration, increases seizure risk.
2) PDE inhibitors and nitrates
3) Betta blockers in heart rate below 60 (can't remember if its contraindication or just recommendation to DC betta blocker)


Nothing else comes to mind... Please help out and share what you guys remember

#1 is not contraindicated either, especially if they are taking VPA for non-seizure reasons. In patients with seizures controlled on VPA it's more just use an alternative if you can and most of the time there is an alternative. But there are times when you have to use a carbapenem or the patient will die. So knowing how to manage it is just as important as knowing the interaction. Increasing the VPA dose is pretty much hopeless so usually bridging with another antiepileptic like keppra until the VPA level is therapeutic again works best but there is not a lot published on this.

 

[HelpfulPharmer1]

Please post the mechanism for renal insult as a result of statin / biaxin D/DI

Here is the mechanism: Please also see the attached file
''Level 1 (Severe)(1 result)
Drug to Drug Interactions Clarithromycin and Simvastatin

Clarithromycin increases potential side effects of Simvastatin.

The concurrent use of clarithromycin and simvastatin is contraindicated due to the risk of myopathy and rhabdomyolysis. If no alternative to a short course of clarithromycin therapy is available, simvastatin use must be suspended during clarithromycin treatment. Simvastatin is metabolized by CYP3A4, and clarithromycin is a strong inhibitor of CYP3A4.''

 

[CetiAlphaFive]

Here is the mechanism: Please also see the attached file
''Level 1 (Severe)(1 result)
Drug to Drug Interactions Clarithromycin and Simvastatin

Clarithromycin increases potential side effects of Simvastatin.

The concurrent use of clarithromycin and simvastatin is contraindicated due to the risk of myopathy and rhabdomyolysis. If no alternative to a short course of clarithromycin therapy is available, simvastatin use must be suspended during clarithromycin treatment. Simvastatin is metabolized by CYP3A4, and clarithromycin is a strong inhibitor of CYP3A4.''

And you think kidney damage is the primary concern there?

 

[Sabril]

So knowing how to manage it is just as important as knowing the interaction.

agreed 200%. I work in an independent pharmacy so I am not under as much pressure as my colleagues working in chains. However, I do really wish to know more of the "red flags" and how to resolve them quickly. I really hope that more of us would care enough to contribute to this discussion. I really feel that it should be expanded from just contraindications to the "no-no's" in pharmacy that can land us in hot water.

Here are what I can think of for now. Please feel free to correct me:
1) Direct acting anticoagulants (like xarelto and eliquis) and NSAIDs: increased bleeding risk. what I do is I suspend the NSAID prescriptions and tell patients to take tylenol (if possible).
2) any protease inhibitors (and the new hep-C drugs also) and statins: increase level of most statins. In my opinion just as bad or even worse than the clarithromycin or -azoles antifungals interactions because you take these meds chronically. I recommend the docs to change to pravastatin. I know it is a cr@ppy drug but it seems to be the safest choice. Even atorvastatin and rosuvastatin are suspects according to some sources. In any case I will suspend the statin until I get some response from the doc.
3) oral contraceptives, especially estrogen containing meds: interact with everything under the sun. A big liability as far as I am concerned. I type into the label itself after the instruction: "Many drug interactions. Please consult your pharmacist" In fact if I do not know for sure if there is an interaction, I always recommend back-up methods. I don't want to pay child support for anyone (not even my own-crossing my fingers)
4) furosemide and digoxin: I know there is a serious risk here, but I admittedly fail to catch them all the time. I don't know if any pharmacists actually recommend potassium to the doc.

I type things on the labels that I feel are important because I don't want to deal with "he says, she says" afterward, even if the info are preprinted on the auxiliary labels. Again, I work for an independent place so I have a little more leeway than my colleagues I guess.