Prior to starting a systemic medication for psoriasis, it is necessary to discuss effects on pregnancy and fertility. Pregnancy is an absolute contraindication for methotrexate and acitretin use because of the drugs’ teratogenicity. Fetal death and fetal abnormalities have been reported with methotrexate use in pregnant women.8 Bone, central nervous system, auditory, ocular, and cardiovascular fetal abnormalities have been reported with maternal acitretin use.9 Breastfeeding also is an absolute contraindication for methotrexate use, as methotrexate passes into breastmilk in small quantities. Patients taking acitretin also are strongly discouraged from nursing because of the long half-life (168 days) of etretinate, a reverse metabolism product of acitretin that is increased in the presence of alcohol. Women should wait 3 months after discontinuing methotrexate for complete drug clearance before conceiving compared to 3 years in women who have discontinued acitretin.8,10 Men also are recommended to wait 3 months after discontinuing methotrexate before attempting to conceive, as its effect on male spermatogenesis and teratogenicity is unclear. Acitretin has no documented teratogenic effect in men. For women planning to become pregnant, apremilast and cyclosporine can be continued throughout pregnancy on an individual basis. The benefit of apremilast should be weighed against its potential risk to the fetus. There is no evidence of teratogenicity of apremilast at doses of 20 mg/kg daily.11 Current research regarding cyclosporine use in pregnancy only exists in transplant patients and has revealed higher rates of prematurity and lower birth weight without teratogenic effects.10,12 The risks and benefits of continuing cyclosporine while nursing should be evaluated, as cyclosporine (and ethanol-methanol components used in some formulations) is detectable in breast milk.
Drug Contraindications
Hypersensitivity to a specific systemic nonbiologic medication is a contraindication to its use and is an absolute contraindication for methotrexate. Other absolute contraindications to methotrexate are pregnancy and nursing, alcoholism, alcoholic liver disease, chronic liver disease, immunodeficiency, and cytopenia. Contraindications to acitretin include pregnancy, severely impaired liver and kidney function, and chronic abnormally elevated lipid levels. There are no additional contraindications for apremilast, but patients must be informed of the risk for depression before initiating therapy. Cyclosporine is contraindicated in patients with prior psoralen plus UVA (PUVA) treatment or radiation therapy, abnormal renal function, uncontrolled hypertension, uncontrolled and active infections, and a history of systemic malignancy. Live vaccines should be avoided in patients on cyclosporine, and caution is advised when cyclosporine is prescribed for patients with poorly controlled diabetes.
Pretreatment Screening
Because of drug interactions, a detailed medication history is essential prior to starting any systemic medication for psoriasis. Apremilast and cyclosporine are metabolized by cytochrome P450 and therefore are more susceptible to drug-related interactions. Cyclosporine use can affect levels of other medications that are metabolized by cytochrome P450, such as statins, calcium channel blockers, and warfarin. Similarly, acitretin’s metabolism is affected by drugs that interfere with cytochrome P450. Additionally, screening laboratory tests are needed before initiating systemic nonbiologic agents for psoriasis, with the exception of apremilast.
Prior to initiating methotrexate treatment, patients may require tuberculosis (TB), hepatitis B, and hepatitis C screening tests, depending on their risk factors. A baseline liver fibrosis assessment is recommended because of the potential of hepatotoxicity in patients receiving methotrexate. Noninvasive serology tests utilized to evaluate the presence of pre-existing liver disease include Fibrosis-4, FibroMeter, FibroSure, and Hepascore. Patients with impaired renal function have an increased predisposition to methotrexate-induced hematologic toxicity. Thus, it is necessary to administer a test dose of methotrexate in these patients followed by a complete blood cell count (CBC) 5 to 7 days later. An unremarkable CBC after the test dose suggests the absence of myelosuppression, and methotrexate dosage can be increased weekly. Patients on methotrexate also must receive folate supplementation to reduce the risk for adverse effects during treatment.
Patients considering cyclosporine must undergo screening for family and personal history of renal disease. Prior to initiating treatment, patients require 2 blood pressure measurements, hepatitis screening, TB screening, urinalysis, serum creatinine (Cr), blood urea nitrogen (BUN), CBC, potassium and magnesium levels, uric acid levels, lipid profile, bilirubin, and liver function tests (LFTs). A pregnancy test also is warranted for women of childbearing potential (WOCP).
Patients receiving acitretin should receive screening laboratory tests consisting of fasting cholesterol and triglycerides, CBC, renal function tests, LFTs, and a pregnancy test, if applicable.
After baseline evaluations, the selected oral systemic can be initiated using specific dosing regimens to ensure optimal drug efficacy and reduce incidence of adverse effects (eTable).