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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 5

💊 Haloperidol PK fact:

Lipophilic, distributes widely into brain & fat

Brain conc. = 10–30× higher than serum

Serum t½: ~15–30h

Brain t½: ~6.8 days

👉 Even weeks after stopping, brain levels may remain clinically relevant.

#PalliativeCare #MedEd #Pharmacology

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Reposted by Pharmacopalliation

Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

💊FLIP-FLOP KINETICS📉

Have you ever wondered why immediate-release opioids reach steady state quickly, but modified-release formulations can take 2–3 days?

The answer lies in a fascinating pharmacokinetic phenomenon called flip-flop kinetics.

Let’s unpack it simply, using opioids as our guide

🧵

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

Visual representation:

Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

=== 🔄 A Simple Analogy===

IR opioids = Drinking juice straight from a glass 🥤 — quick in, then slowly processed (comaparatively)

MR opioids = Drinking through a thin straw 🧃 — the body’s ready to process, but has to wait for it to arrive.

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

===🔍 Clinical Implications===

Don’t assume a long half-life = slow clearance — it could just be slow absorption.

Be cautious as kinetics may differ depending on formulation (IR v MR).

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

The time to reach steady state is delayed,

Often taking 2–3 days with modified-release opioids.

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

But because it's entering more slowly, the absorption becomes the rate limiting step — not elimination (see graph below)

This is flip-flop kinetics → where the usual roles are reversed

Here, the terminal half-life seen on the graph reflects absorption, not elimination. That’s why:

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

=== Modified-Release (MR) Opioids: Flip-Flop Kinetics ===

Now, consider sustained-release morphine or oxycodone.

The MR formulation slows the rate of absorption dramatically

Once the drug enters the bloodstream, it's now cleared comparatively quicker to the rate of absorption

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

As a result:

Steady state is reached in 4–5 elimination half-lives

Which may be as little as a day or less for some IR opioids

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

The terminal elimination phase of the plasma concentration-time graph reflects elimination

This is standard pharmacokinetics — absorption is fast, so elimination becomes the rate-limiting step (see graph below)

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

===Immediate-Release (IR)
Opioids: Standard Kinetics===

When you give a patient IR morphine the drug is absorbed quickly from the gut

The body eliminates it comparatively slower than the time taken for absorption

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 6

💊FLIP-FLOP KINETICS📉

Have you ever wondered why immediate-release opioids reach steady state quickly, but modified-release formulations can take 2–3 days?

The answer lies in a fascinating pharmacokinetic phenomenon called flip-flop kinetics.

Let’s unpack it simply, using opioids as our guide

🧵

1 1 4

Pharmacopalliation @pharmacopalliation.bsky.social · Sep 5

💊 Haloperidol PK fact:

Lipophilic, distributes widely into brain & fat

Brain conc. = 10–30× higher than serum

Serum t½: ~15–30h

Brain t½: ~6.8 days

👉 Even weeks after stopping, brain levels may remain clinically relevant.

#PalliativeCare #MedEd #Pharmacology

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Pharmacopalliation @pharmacopalliation.bsky.social · Sep 4

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Pharmacopalliation @pharmacopalliation.bsky.social · Aug 30

Thanks to that open imidazole ring at low pH, it can be made into a stable injectable solution.

Most other benzos (diazepam, lorazepam) are poorly water soluble and need organic solvents like propylene glycol → which cause venous irritation. Midazolam avoids that.

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Pharmacopalliation @pharmacopalliation.bsky.social · Aug 30

In acidic environments (like in the injection solution), the ring is protonated → water-soluble → stable for IV prep.

At physiological pH, the ring closes → lipophilic → rapid CNS penetration → quick onset of action.

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Pharmacopalliation @pharmacopalliation.bsky.social · Aug 30

💡 Midazolam is actually water-soluble in its vial, but becomes lipid-soluble once it enters the body.

That’s unusual for a benzodiazepine. The trick lies in its imidazole ring 👇

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Pharmacopalliation @pharmacopalliation.bsky.social · Aug 27

💊💊ALFENTANIL💊💊
Alfentanil’s pKa ~6.5, much lower than fentanyl (~8.4) or morphine (~8.0)

At physiologic pH (7.4), ~90% of alfentanil exists in the unionised, lipid-soluble form → crosses the blood–brain barrier very rapidly

This explains why alfentanil has the fastest onset of action of any opioid

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Reposted by Pharmacopalliation

Rick Bauer (he/him/él) @nvrflycoach.bsky.social · Feb 14

www.youtube.com/watch?v=BbNi...

Palliative Care PSA - We’re the fire department, not the fire.

YouTube video by Jared Rubenstein

www.youtube.com

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Pharmacopalliation @pharmacopalliation.bsky.social · Feb 13

🎉 Excited to announce our new textbook, Oxford case histories in palliative medicine! 🎉

Dive into comprehensive insights and practical approaches to enhance patient care. Thank you to everyone who contributed 👏
📚 #PalliativeCare

Oxford Case Histories Palliative Medicine - Google Books https://search.app/3WbLiPnPEdhSDvjR8

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Reposted by Pharmacopalliation

Pallmedpro @pallmedpro.bsky.social · Feb 10

Edited by palliative medicine physician Dr Jonathan Pickard, and consultant pharmacist Mr Jonathan Hindmarsh, 54 expert authors provide “diagnostic skills and clinical reasoning that helps temper knowledge and understanding with pragmatism and practicality in the face of life-limiting illness.”

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Reposted by Pharmacopalliation

Pallmedpro @pallmedpro.bsky.social · Feb 10

It’s finally here! @oxfordunipress.bsky.social Oxford Case Histories in Palliative Medicine “guides medical professionals and trainees through 52 cases curated to illustrate the varied and often complex landscape of palliative medicine.”
oxford.ly/4hG4C9B

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Reposted by Pharmacopalliation

Pharmacopalliation @pharmacopalliation.bsky.social · Dec 6

TRAMADONT: Ten reasons to avoid Tramadol.

a stop sign that is red and white

ALT: a stop sign that is red and white

media.tenor.com

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Reposted by Pharmacopalliation

Pharmacopalliation @pharmacopalliation.bsky.social · Dec 9

Psychostimulants and depression in palliative care:

A short thread 🧵

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Reposted by Pharmacopalliation

Pharmacopalliation @pharmacopalliation.bsky.social · Dec 14

When prescribing dexamethasone, remember enzyme inducers, such as carbamazepine and phenytoin, can significantly reduce its serum levels. In some cases dexamethasone doses may need to be increased 2 - 4 fold! Particular caution needed in high risk indications such as MSCC!

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