Question
What is the risk from this presciption error and taking half-dose 3TC?
21 November 2010. Related: All topics, CD4 and viral load, Changing treatment, Resistance.
I was diagnosed HIV+ in 1998. I started meds almost immediately and have been through a variety of HAART combinations. I have my HIV meds delivered by a home care delivery company.
My current prescription is for a single daily dose of 300 mg of lamivudine (3TC), along with raltegravir 400 mg twice daily & efavirenz 600 mg once daily. I have been on raltegravir for about three years after short (unsuccessful due to side-effects) periods on Truvada and with tenofovir in other combinations.
Today, by chance, I was looking at the label on the lamivudine container supplied in August & noticed that I had been supplied 150 mg lamivudine tablets and that I should have been taking two of the tablets daily instead of the single tablet I’m used to taking.
I was not given any warning or notification of this, although I did notice a colour change of the pills, but I just assumed that I had been supplied with a generic version of the drug as part of NHS cost saving exercises. My bad.
So, since August this year, I have been under-dosing lamivudine by 50%. I immediately contacted my dispensing pharmacy who advised me to increase the dose & come in for urgent viral load testing.
I’ve been very careful adhering to my meds since my diagnosis and have had an undetectable viral load for over 10 years and steadily increasing CD4 counts from 120 immediately after diagnosis to around 900 now.
My pharmacy has promised to take this up with the home care delivery company, as there are implications for others in my situation. I will try to make sure this happens.
Should I be worried for my future treatment prospects at all? Lamivudine has been one of the backbone drugs of my successful treatment to date.
What alternatives are available for lamivudine if I have developed resistance?
Any thoughts would be appreciated.
Answer
Hi
Thank you for contacting us and for allowing us to post the answer online.
Firstly, the viral load test is important enough to prioritise for as soon as you can. If you didn’t go yesterday, then if you can go today it is a good idea. You want to know your viral load before the renewed 300mg has any chance to change it. Your clinic needs to get the results back from the lab quickly, and pay for a 1 or 2 day turnaround.
There is a good chance that everything will be fine and you will not have developed resistance. You will have been on 2.5 drugs rather that 3 drugs, but for several months. As your viral load has been undetectable for so long, this may have still been enough to maintain an undetectable viral load. I’d rather assume this positive outcome until you get the viral load results back. There will be other combinations you can use, so you will be ok.
You need the result promptly because if your viral load has rebounded even to a low level, a resistance expert might recommend an alternative to just returning to the 300mg dose.
Your pharmacy response means they should be prioritising this. The error will be seen as extremely serious by your clinic. I would also expect that they will raise this at the highest level with the contractor and Trust.
This particular error has the potential to lead to resistance to all the drugs in your combination.
Otherwise, getting blood drawn for the VL test, and then getting the result is the most important first step. Hopefully, everything will be fine and this will not have any impact on your health. If it has rebounded I can then go through different options.
I wondered whether the dosing details changed with the new formulation – ie did the label change to ‘take two 150mg daily’ – this would help clarify whether this was a formulation changes, perhaps relating to cost, or a prescription error, when the wrong pills were dispensed.
Even if this was on the label, you are not at fault for what has happened. This is a serious error by the distribution company and it will be logged as such and taken further. People whould receive clear notification if the formulation of any routinely precribed medication changes for any reason.
It would also really help to know what happens with your clinic and the test results, as this may change the information online.
You are right that this is important for other patients.
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