Calcipotriene vs Sotyktu

Dosing is as simple as it gets for a systemic drug. No loading dose, no build-up, no weight adjustment.

Starting dose: 6 mg once a day from day one. Full dose from the start.

Going up: No higher approved dose for psoriasis. If it is not working, the conversation is about switching.

Usual dose: 6 mg once a day, long term.

Kidney function: No dose change for most levels of reduced kidney function.

Severe liver disease: Not recommended, so tell your doctor about any liver condition before you start.

Everyone is screened for tuberculosis before starting, with a skin test or a TB blood test, and a chest X-ray if positive. Dormant TB is treated first. This applies even though it is a tablet rather than an injected biologic.

Hepatitis B and C are usually checked at the same time.

Liver blood tests are often checked before starting and again if there is a reason to. Some people show a rise in creatine kinase, a muscle enzyme, or in triglycerides, so those may be looked at too. There is no rigid schedule like methotrexate's; how often anything is repeated is your doctor's judgment.

The rest is clinical. Report repeated infections, cold sores that keep coming back, mouth ulcers that will not heal, and unexplained muscle pain. Skin should be checked periodically, as on any drug that damps down the immune response.

Once a day, at whatever time suits you, with or without food. Pick one time and keep to it, because a daily tablet is easy to lose track of in a way a fortnightly injection is not. Attaching it to something you already do, like brushing your teeth at night, works better than intending to remember.

Swallow the tablet whole with water. Do not crush, split or chew it. If it upsets your stomach, take it with a meal.

Take it as soon as you remember on the same day. If you do not remember until the next day, skip it and take that day's tablet as usual. Never take two in one day. Missing the occasional dose will not undo months of progress, but repeatedly missing them is one of the commonest reasons a treatment looks like it has stopped working.

First doseTaking it: One tablet a day, with or without food.

Weeks 1 to 4Starting: Itch usually eases before the plaques look different. Early side effects show now, most often a cold, a cold sore or a mouth ulcer.

Weeks 4 to 16Working: Scale lifts and plaques flatten steadily. Scalp psoriasis often improves noticeably here, before the trunk.

Week 16Judge it here: Where the trials measured, and the fair point to decide. More than half reached at least a 75 percent improvement in how much skin was involved and how severe it was; a smaller share were clear or nearly clear.

Months 3 to 6Palms and soles: Stubborn on every treatment, slower than plaques elsewhere.

Months 6 to 12Nails: Nails change last, because a nail takes months to grow out. Judge the new growth at the base, not the damaged tip.

Beyond 16 weeksLong term: Responders often keep improving slowly through the first year. Because it is a small molecule, the body does not make antibodies against it, so the gradual loss of effect seen with some injected drugs is not an issue here.

Brand only. There is no generic and will not be for years, so there is no cheaper equivalent. The list price is high, in the same range as the injected biologics over a year, which surprises people who assume a tablet must be cheaper.

Almost nobody pays it. What matters is what your plan does, and approval takes paperwork. Prior authorization is close to universal, and most plans want documented failure of something cheaper first: phototherapy, methotrexate or apremilast.

Manufacturer copay cards can bring the monthly cost down to very little on commercial insurance. By law they cannot be used with Medicare or Medicaid. For those plans, or no insurance, the manufacturer's patient assistance program and independent foundations are the usual routes, and the rules change regularly.

One thing in its favor on cost: no infusion visits, no injection training, no cold chain, so the costs around the drug are lower even when the drug is not.