Transitioning from olaparib capsules to tablets

Olaparib capsules and tablets are both TGA/PBS approved for initial maintenance treatment of platinum-sensitive recurrent high grade serous epithelial ovarian, fallopian tube or primary peritoneal carcinoma in women with BRCA1 or BRCA2 mutations.^r,r

The phase II trial by Ledermann et al used the capsule formulation of olaparib with a substantial pill burden of 16 capsules a day due to poor solubility.^r The phase III SOLO2 trial demonstrated that maintenance therapy with olaparib tablets significantly prolongs progression free survival and substantially reduces the pill burden to 4 tablets a day due to greater bioavailability.^r 

Given the advantages in terms of reduced pill burden, changing to the tablet formulation may improve patient convenience and adherence to treatment. Although efficacy is similar between the two formulations, they are not directly interchangeable given differences in pharmacokinetics, pharmacodynamics and side effects. This is important to be aware of when transitioning patients between the formulations.^r,r

There is no published clinical data investigating changing from the olaparib capsule to tablet formulation, particularly in patients who are already on a reduced capsule dose. The following recommendations are based on clinical consensus opinion. Anecdotal experience from patients to date appears to be positive but ultimately clinicians should use their best judgement in transitioning patients between the formulations.^r,r

Practice points:

• Capsules can be switched to tablets when the next dose is due, or alternatively capsules can be ceased for 2 to 3 days (3 to 5 half-lives) prior to commencing the tablets.
• Monitor patients closely for the first 3 months after changing formulations as further dose modifications may be required depending on tolerability. Suggested monitoring includes FBC and EUC weekly for the first month, then monthly for the first year, then as clinically indicated.
• Dose escalation of the tablet formulation may be considered in some patients who are already on a reduced capsule dose. For example, if the dose reduction of the capsules was due to gastrointestinal toxicity and the patient tolerates the tablet formulation well. Caution should be exercised in the event of dose reductions due to myelosuppression, including anaemia.

Patients and/or their carers should be educated about the:

• difference between capsule and tablet formulations and that a reduction in number of tablets will not alter the efficacy of treatment
• correct dose to take to avoid dosing errors and adverse effects
• monitoring requirements when changing from capsules to tablets.

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