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r/AskDocs•
Cullly

Medication Timing & Strengths Questions

Physician Responded

I got a new psychiatrist. I went through my medication and he told me to change how I take them. It is now a week later and things are a LOT better. What he said is the opposite to what the previous psychiatrist said.

BEFORE:

  • 46M with ADHD, ASD, Asthma, and Major Depressive Disorder (MDD).
  • I took 150mg Venlafaxine at night for MDD. (for only a few weeks - it's a new med)
  • I take 72mg Concerta at morning for ADHD
  • I took 1 Cetirizine in morning for a heat/friction based allergy I seem to have
  • I took 3x25mg Phenergan (Promethazine HydroChloride) at night to help me sleep. (sleep problem is adhd related).

I was complaining of constant tiredness. I thought this was me just getting used to a new drug.

NEW CHANGES SUGGESTED BY PSYCHIATRIST:

  • Take Venlafaxine at morning -> he says it doesn't cause drowsiness and works better this way.
  • Don't take Cetirizine as it causes drowsiness. Use Loratidine or Desloratidine instead.
  • Completely stop Phenergan as it causes drowsiness even after waking.

This completely worked. I am still talking to my GP to see about a different sleep aid as I still can't get to sleep.

MY QUESTION IS: How do you learn the concentration levels of medication? What I mean by that is: Every medication lasts a specific length of time. Every medication gets stronger or weaker at different points. Here is an example for Concerta showing peak concentration at 6-7 hours in.

https://www.janssenlabels.com/package-insert/product-monograph/prescribing-information/CONCERTA-pi.pdf#page=21

I could fix a lot of my issues if I understood these more. Is there any easy way to find these? I didn't know Cetirizine made you drowsy, and I didn't know that Phenergan worked for longer than ~8 hours.

Thanks for any help you can give.

Posted Aug 31, 2023, 3:21 PM UTC

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DrSocialDeterminantsPhysician•

Your psychiatrist made some great recommendations first off.

That said... I think the first question you should be thinking about is more around what causes drowsiness vs not. In your situation, it is definitely important information for you to know what antihistamines cause drowsiness vs which one's are non-drowsy (like loratadine).

The amount of Phenergan you take probably contributes to the fact that it lasts longer when you wake.... it doesn't typically last that long but perhaps it was how much you were taking.

I don't think it's expected for you to know drug half lives and period of efficacy for everything. That's why you are working with a doctor who can help troubleshoot these issues. It's more important that you think about what the meds are and what main effects + side effects they cause.

If you are insistent... every medication has a drug monograph that describes the pharmacodynamics and there's many drug repositories/databases that collects the information. https://www.drugs.com/ is one basic one you can use.

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CulllyOPLayperson/not verified as healthcare professional.•

Thank you for the reply.

I just feel like this issue could be sorted earlier if I understood pharmacodynamics more. I know I'm not expected to. Sometimes it takes weeks or longer before I can talk to a doctor about it.

I'd like to at least know some basics. Like for Concerta, I don't need to eat in the first few hours, but at hour 5 onwards, I need to eat something decent or I will feel bad (jittery/nervous/tense). If I knew this for all the things I take, I could avoid silly issues here and there.

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DrSocialDeterminantsPhysician•

I don't know if eating specifically addresses the jittery element of concerta so I'm going to leave that aside.

It doesn't hurt to do some reading but I would emphasize again that when you try to make changes yourself it could go sideways real fast too. More importantly, by the time the doctor sees you they would be misled into thinking you are taking meds one way and you've changed it. That can confuse the doctor you're working with.

It's important to keep an open line of communication and discuss changes with your doctor to help them be aware and informed with your decisions and can adjust before any problems happen.

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CulllyOPLayperson/not verified as healthcare professional.•

I would emphasize again that when you try to make changes yourself it could go sideways real fast too.

Thank you. I have a few doctors, so sometimes one doesn't know the other changes until I point it out. I know decisions should be discussed with a doctor, but I'm not going to bring up something unless I think it's relevant. You are right. I shouldn't overdo the information or it may confuse the doctor.

Thanks for the help!

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DrSocialDeterminantsPhysician•

I'm not going to bring up something unless I think it's relevant.

please be careful with this too... we may not know if it's relevant or not unless you bring it up

good luck

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