The following post is an amalgamation of research and draws from a variety of sources. Clinical resources are subject to regular updates as scientific understanding improves. This post is for informational purposes, but it is not a peer-reviewed, controlled clinical document and should NOT be taken as medical information nor clinical guidelines.

 

Instead, it is provided for informational purposes and should serve as a useful prompt to do your own research, review appropriate clinical sources and seek qualified medical advice when making your own decisions.

 

 

Drug Name

 

Paroxetine

 

Brand and Other Names

 

Paxil, Brisdelle, Seroxat, Pexeva, Aropax, Xetanor, Paroxet, Serupin

 

Drug Classification

 

SSRI (Selective Serotonin Reuptake Inhibitor)

 

Forms of the Drug and Dosages

 

IR (immediate release) tablets- 10mg, 20mg, 30mg, 40mg

 

CR (controlled-release) tablets- 12.5mg, 25mg, 37.5mg 

 

Oral Suspension (liquid)- 10mg per 5ml (always check the bottle for ratio)

 

Low dose capsules- 7.5mg

 

Half Life

 

15-21 hours

 

Peak Plasma

 

6.4 hours

 

Dosing

 

Take paroxetine daily at the same time. Never miss doses or skip days. (This is not a safe way to taper off this drug)

 

Medication Guide, Prescribing Information and Side Effects

 

https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/020031s077lbl.pdf

 

Dependency on the Drug

 

Dependency can occur in less than 4 weeks of taking this drug. Tapering slowly is the safest way to stop taking this drug. Withdrawal symptoms can be severe and it is never recommended to quit the drug outright. A harm reduction protocol is to taper at a maximum reduction of 10% of the current dose every 28 days. 

 

Affected Receptors and Transporters

 

Serotonin Transporter (SERT)

 

Nonadrenaline uptake inhibitor of NET

 

Norepinephrine transporter (NET)

 

Histamine Receptors

 

GABA Transporters (GATs)

 

Glutamate Transporters

 

Alpha-1, Alpha-2 and Beta adrenoceptors

 

Muscarinic cholinergic receptors

 

5 Ht1

 

5 Ht2

 

Dopamine

 

GRK2 (G protein-coupled receptor kinase)

 

P-glycoprotein (P-gp)

 

Tyrosine kinases (KIT, JAK, ABL, SRC, MET, FYN)

 

Affected Enzymes

 

CYP2D6, CYP2B6, CYP3A4, CYP1A2, CYP2CP, CYP2C19 from the Cytochrome P450 system

 

Nitric Oxide Synthase (NOS)

 

Additional Cautions

 

Grapefruit or any component of grapefruit (specifically juice) should be avoided. It increases the way the drug is metabolized due to its affect on the CYP3A4 and CYP2D6 enzymes. These enzymes are needed to metabolize paroxetine. Grapefruit (juice specifically) inhibits said enzymes. It causes paroxetine to stay longer and at higher concentrations in the bloodstream. This affect can last up to 72 hours from consumption of grapefruit and could cause overdose/serotonin syndrome. Earl Grey Tea can have the same effect due to the bergamot.

 

Always use a drug checker when adding medications or supplements while taking paroxetine.

 

See above link under Medication Guide for more contraindications and cautions.

 

Do It Yourself Liquid

 

Paroxetine is soluble at a 2:1 ratio of water to tablet/powder. The filler is not soluble so particles will be visible. Stir or shake before extracting your dose via syringe or micropipette. As you taper to lower doses, the solution can be further diluted using a great ratio of water to tablet/powder for accuracy.

 

Use room temperature drinkable water (tap, distilled, spring, etc) to make your solution. Allow at least 30 minutes at room temperature to help the pill dissolve. The pill can be crushed to speed up the process. Stability of the solution is unknown. Discard unused portion. (some have safely used refrigerated diy liquid for 3 days-exercise caution)  Accuracy and using the same consistent method is important.

 

How to Cut and Weigh Tablets/Capsules

 

For tablets

 

If the company has a line in the center of the tablet (scored), this means the drug is evenly distributed throughout it. It is recommended to weigh 5 to 10 pills collectively and get an average weight of your pill. This is referred to as mgpw or milligrams of pill weight. That will be your standard to make calculations in determining your pill weight as you taper and cut. Using a pill cutter works well to do the big cuts of a pill and then use a one-sided razor, file, or very sharp knife to shave the pill carefully to get the desired weight from there. Your dose in milligrams (mg) sometimes will be referred to as mgai or milligram of actual ingredient.

 

An option, to cutting and shaving pills, is to grind the pills to powder and fill capsules with the necessary weight. This is the preferred method if your pills are not scored. Capsules vary in weight as well and will need to be added to the powder’s weight for accuracy.

 

For capsules

 

The drug is evenly mixed with filler, so it is a matter of opening the capsule and weighing the powder (mgpw). It will weigh more than the dosage (mgai) of the capsule due to the filler. It is recommended to weigh the filler individually of 5 to 10 capsules and get an average weight. Use that weight moving forward in determining your cuts in dosages.

 

Recommended weigh scales can be anything like the Gem20 jewelry scale on Amazon, to higher end Analytical Balances.

 

Crossover

 

It is preferable to stay with the same manufacturer of your drug because the active ingredient and filler does vary slightly and can cause withdrawal. Sometimes this is unavoidable. Also, at some point, you may wish to change from tablet/capsule and transition to liquid. Crossover is best done from a stable state especially when going from tablet/capsule to liquid.

 

This is the safest way to do either crossover.

 

For 4-7 days, ¼ of your dose of the new manufacturer or liquid/ ¾ of your dose in the regular form.

 

For 4-7 days, ½ of your dose of the new manufacturer or liquid/ ½ of your dose in the regular form.

 

For 4-7 days, ¾ of your dose of the new manufacturer or liquid/ ¼ of your dose in the regular form.

 

Full dose in the new form.

 

If at any stage, withdrawal symptoms show up, hold till they subside then proceed with the schedule.

 

Tapering Under 5mg

 

Once you reach under 5 mg, the effect of paroxetine on the CYP2D6 can lessen the inhibition of CYP2D6 causing the metabolism of paroxetine to accelerate. This may affect the drug in the plasma level to drop more drastically adding to a possible increase in withdrawal symptoms. If this occurs, it may be necessary to adjust by tapering less than 10% every 28 days and/or hold longer between drops in dosage.

 

Jump off Dose

 

Lower is always better. It takes a long time to do a careful taper. This is not the time to rush it. Success has been achieved by those jumping off at .016 mg and even lower. It is important to no longer have increased withdrawals during your last few dosage drops. You should be feeling stable.

Whoa! This is so helpful! Thank you!

@LostinCanada ...this is indispensable knowledge. Awesome to have it all put together in a neat little package. Im happy that those just beginning this journey have so much more information available than many of us did. 

38 minutes ago, Rob9H9 said:

@LostinCanada ...this is indispensable knowledge. Awesome to have it all put together in a neat little package. Im happy that those just beginning this journey have so much more information available than many of us did. 

Hey Welcome to the forum @Rob9H9 when you have a minute it would be great if you could start a topic in the introduction forum and say hello! 🙂 Chippy

@LostinCanada you are such an incredible resource to this community. The time, and research you put into this is invaluable and will help others for years to come. Thank you for helping us all learn. 😊🙏

Thank you @LostinCanada! This took some doing. That was very generous on your part, and I appreciate it. I wish you the best on your future tapering.

xxoo Jamie