Biologic and small-molecule treatment principles

01Purpose and principlesWhat the treatment does and how it fits into care.

Targeted treatment is chosen after confirming diagnosis, severity and important life impact and after appropriate topical, phototherapy or conventional systemic treatment has failed, is contraindicated or is unsuitable under the live appraisal. Psoriasis pathways may use TNF, IL-12/23, IL-17, IL-23 or TYK2 targeting. Atopic dermatitis pathways include IL-4/13, IL-13 and JAK inhibition. Chronic spontaneous urticaria may use IgE targeting. The drug must match the disease and appraisal; a response in one inflammatory condition does not create an indication in another.

Mechanism predicts some hazards. TNF blockade weakens granuloma maintenance and can reactivate tuberculosis or hepatitis B. IL-17 blockade can permit mucocutaneous Candida and exacerbate inflammatory bowel disease. IL-4/13 pathway blockade can cause conjunctivitis and keratitis. JAK inhibition affects multiple cytokine signals and can alter blood counts, liver enzymes and lipids while increasing zoster and thrombotic or cardiovascular risk in susceptible people. Individual agents within a class still differ, so the current SmPC supersedes a class shorthand.

Shared decisions should compare expected speed and magnitude of response, injection or tablet preference, dosing burden, comorbid arthritis or bowel disease, pregnancy, travel, vaccination and likely adherence. Establish who supplies treatment, which service receives results and how urgent advice works. Review infection and medicine changes at every contact, including private prescriptions and over-the-counter products. Biosimilar switching can be appropriate but should be explained, documented and traceable rather than occurring through an unexplained brand substitution.

Key points

A marketing authorisation does not equal NHS eligibility: verify the current disease-specific NICE technology appraisal, severity threshold, previous-treatment requirement and local pathway before offering a drug.
Biologics are antibodies or receptor proteins targeting cytokines or cells; small molecules enter cells and inhibit signalling enzymes such as JAK, TYK2 or PDE4 and often need more laboratory and interaction surveillance.
Baseline review includes infection history, TB, hepatitis B and C, HIV by risk, vaccination, FBC, renal and liver function, pregnancy plans, malignancy, cardiovascular and thrombotic risk and disease-specific comorbidity.
Complete needed live vaccines before immunosuppression using Green Book timing; live vaccines are generally avoided during biologic or JAK treatment, while non-live vaccines remain important.
Choose by phenotype and comorbidity: inflammatory bowel disease discourages some IL-17 choices, demyelination or severe heart failure affects TNF selection, and recurrent eye disease matters with dupilumab.
JAK inhibitors have serious infection, zoster, MACE, malignancy, thrombosis and mortality warnings; in people aged 65 or over, smokers or those with cardiovascular or cancer risk, use only when no suitable alternative exists.
Do not combine two biologics or a biologic with a JAK inhibitor; additive immune suppression lacks routine benefit and increases serious infection risk.
Record generic and brand or biosimilar name, batch where available and exact dosing interval so adverse events and switching remain traceable.
Assess response at the appraisal-specified time using an objective disease measure and quality-of-life outcome; stop or switch when the required response is not achieved.
A long biologic half-life means risk persists after withholding; serious infection treatment, pregnancy planning and surgery cannot be managed by simply skipping one dose without specialist timing.

02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.

Appropriate targeted-treatment candidate

Diagnosis and severity meet a current appraisal, required previous treatments were inadequate or unsuitable, and baseline risks can be mitigated with reliable follow-up.

Latent or active infection signal

TB exposure, chronic cough, fever, weight loss, night sweats, hepatitis history, recurrent zoster or travel-related parasite risk changes selection and timing.

JAK high-risk profile

Age 65 or over, current or past long-term smoking, atherosclerotic cardiovascular risk, malignancy risk or previous thrombosis makes an alternative preferable when suitable.

Dupilumab ocular toxicity

New gritty painful red eye, photophobia or visual change can represent conjunctivitis or keratitis and needs early eye assessment rather than automatic discontinuation alone.

IL-17 bowel warning

Persistent abdominal pain, diarrhoea, blood or weight loss during IL-17 blockade raises new or worsening inflammatory bowel disease.

TNF neurological warning

Visual change, sensory loss, weakness or other demyelinating symptoms requires prompt neurological assessment and treatment interruption.

Serious infectionRed flag

Hypotension, hypoxia, confusion, disseminated vesicles or rapidly spreading painful skin infection is an emergency even when inflammatory markers are blunted.

Red flags requiring action

Fever or systemic infection, shingles near the eye, persistent cough or weight loss, new neurological deficit, severe abdominal pain or bloody diarrhoea, chest pain, breathlessness, limb swelling, jaundice, marked cytopenia, anaphylaxis, pregnancy or new malignancy requires prompt treatment interruption and specialist assessment.

03Assessment before treatmentTests and checks that guide safe selection.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Disease severity and eligibility recordFirst step
Why
Demonstrate that the current NICE and local initiation criteria are met.
Interpretation and limitations
Use the named objective and patient-reported measure, document previous treatment dose, duration, failure or contraindication and avoid substituting an unsupported score.
02
TB assessment
Why
Detect active or latent tuberculosis before biologic or small-molecule immunosuppression.
Interpretation and limitations
Combine exposure and symptom history, IGRA or protocol test and chest imaging when indicated; urgent specialist management of active disease precedes immunosuppression.
03
Viral infection screen
Why
Prevent hepatitis or HIV-related complications and plan prophylaxis or monitoring.
Interpretation and limitations
Test hepatitis B surface antigen, core antibody and surface antibody, hepatitis C and HIV according to agent and risk; core-antibody positivity can require hepatology monitoring despite negative surface antigen.
04
Baseline laboratory panel
Why
Establish marrow, liver, renal and metabolic safety before treatment.
Interpretation and limitations
Obtain FBC, renal and liver profiles and add lipids, creatine kinase or other tests for the selected small molecule; use agent-specific thresholds rather than one universal panel.
05
Vaccination review
Why
Reduce preventable infection and avoid live-vaccine exposure during immune suppression.
Interpretation and limitations
Check records and schedule influenza, COVID, pneumococcal, recombinant zoster and other indicated non-live vaccines; give needed live vaccine before treatment with Green Book specialist timing.
06
Pregnancy and reproductive assessment
Why
Select an agent and timing compatible with conception, gestation and breastfeeding.
Interpretation and limitations
Document pregnancy testing when relevant, contraception and paternal or maternal exposure advice from the current SmPC and specialist guideline because class assumptions are unreliable.
07
Response and safety laboratory review
Why
Continue only effective treatment with acceptable toxicity.
Interpretation and limitations
Repeat disease score and life impact at the appraisal time point and monitor blood counts, liver, kidney, lipids or infection markers according to agent, comorbidity and concomitant medicine.

04Treatment approachPreparation, options, escalation and aftercare.

01First-line targeted selectionMatch appraisal, mechanism and personFirst stepFirst lineSevere skin disease remains uncontrolled and targeted treatment is being considered.

1Confirm the live NICE indication, required severity and previous-treatment sequence and document an objective baseline outcome and goals important to the patient.
2Screen infection, vaccination, pregnancy, malignancy, cardiovascular, thrombotic, neurological, bowel and eye risks and map them against candidate mechanisms.
3Agree agent, brand, route, loading and maintenance schedule, laboratory plan, infection and vaccine actions, response deadline and stopping rule.

02Vaccination routeImmunise before immune suppressionA needed live or non-live vaccine is identified during baseline review.

1Give indicated non-live vaccines before treatment when feasible to improve response, but do not delay urgent disease control without a risk-based specialist decision.
2Administer a needed live vaccine before immune suppression and wait the Green Book or agent-specific interval; avoid live vaccination during treatment and for the post-dose interval.
3Vaccinate household contacts appropriately and give exposure advice for varicella, measles and other high-consequence infections.

03Serious-infection routeWithhold and treat without waiting for washoutSystemic, invasive, opportunistic or disseminated infection develops.

1Withhold the targeted medicine, assess sepsis and obtain cultures or PCR without delaying antimicrobial or antiviral treatment.
2Identify last dose, half-life, concomitant immunosuppression, neutrophil count and organ function and involve infection specialists early.
3AlternativeRestart only after adequate recovery and source control, with a documented balance of relapse, reinfection and any need for prophylaxis or an alternative mechanism.

04Response checkpointContinue for measured benefitThe disease-specific induction or appraisal assessment point is reached.

1Repeat the same validated severity and life-impact measures and compare with baseline while checking adherence, technique and newly active comorbidity.
2Continue when the appraisal-defined response and patient-relevant benefit are achieved without unacceptable toxicity; optimise supportive topical care.
3Stop or switch after confirmed inadequate response and investigate paradoxical disease, infection, antibody loss of response or wrong diagnosis before cycling mechanisms.

05JAK safety routeUse only when risk is justifiedAn oral JAK inhibitor is proposed for a person with age, smoking, cardiovascular, malignancy or thrombotic risk.

1AlternativeDetermine whether a suitable non-JAK alternative exists and use the JAK inhibitor only when none is suitable in the MHRA high-risk groups.
2Use the lowest effective licensed dose, address smoking and cardiovascular risk without blame and plan FBC, liver, lipids and infection surveillance.
3Give urgent actions for zoster, fever, chest pain, breathlessness, limb swelling and focal neurology and review need at every renewal.

05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.

TNF inhibitor that can treat severe plaque psoriasis and associated psoriatic arthritis when the required prior-treatment and severity criteria are met.

Adalimumab exemplar for adult plaque psoriasis

Under a current NICE-eligible specialist pathway, give 80 mg subcutaneously initially, then 40 mg every other week starting 1 week after the initial dose; use the specific biosimilar device and current SmPC.

Screen TB and hepatitis, avoid live vaccines and active serious infection, and review demyelination, heart failure, malignancy and injection reactions. Record brand and batch and do not combine with another biologic.

IL-4 receptor alpha blockade reduces IL-4 and IL-13 signalling in eligible moderate-to-severe atopic dermatitis.

Dupilumab exemplar for adult atopic dermatitis

Give a 600 mg subcutaneous loading dose as two 300 mg injections, followed by 300 mg every other week under the licensed and NICE-commissioned adult atopic-dermatitis pathway.

Assess conjunctivitis, keratitis, eosinophilic symptoms and helminth infection, avoid live vaccines and continue appropriate topical care. Pregnancy and age-specific schedules require current specialist guidance.

Oral JAK1-predominant inhibitor offering rapid control for eligible moderate-to-severe atopic dermatitis when benefits justify systemic small-molecule risk.

Upadacitinib exemplar for adult atopic dermatitis

Use 15 mg orally once daily in adults, increasing to 30 mg once daily only when clinically appropriate under the current SmPC and NICE pathway; use 15 mg in people aged 65 years or over and the lowest effective dose.

Screen TB, hepatitis and pregnancy; monitor FBC, liver and lipids and manage interactions. Avoid live vaccines and combination biologic treatment. Apply MHRA restrictions for age, smoking, cardiovascular, malignancy and VTE risk.

06Complications, monitoring and follow-upAdverse effects, response and longer-term review.

Record agent, brand, batch where available, loading date, maintenance interval, missed doses and every concomitant immunosuppressant.
Ask at each contact about fever, cough, weight loss, shingles, wounds, dental infection, travel, vaccines, pregnancy, surgery and new medicines.
Repeat disease-specific severity and quality-of-life outcomes at the NICE appraisal checkpoint and stop ineffective treatment rather than extending induction indefinitely.
Follow agent-specific FBC, liver, renal, lipid and other schedules, increasing frequency after abnormality, infection, dose change or interacting treatment.
Monitor mechanism-linked harms: bowel symptoms with IL-17, neurological or heart-failure symptoms with TNF, eye disease with dupilumab and thrombosis or MACE with JAK.
Review skin-cancer and cervical-screening participation according to risk and national programmes and examine any persistent new lesion promptly.
Plan surgery, travel vaccination and conception early because washout, flare risk and infection risk extend beyond the nominal next-dose date.

07Special situationsVariants, exceptions and circumstances that change the usual approach.

Licence, appraisal and funding differ

A licensed product may lack a NICE recommendation for this disease or person, while a positive appraisal still requires its stated eligibility and commercial arrangement.

Mechanism predicts but does not guarantee

Class effects guide screening, yet individual SmPC differences in dose, interaction and reproductive advice remain clinically decisive.

Half-life outlasts withholding

Skipping one biologic dose does not immediately restore immunity, so serious infection care begins while residual drug remains active.

Non-live vaccines still matter

Immune response may be reduced during treatment, but influenza, COVID, pneumococcal and recombinant-zoster vaccination can still prevent severe disease.

Biosimilar remains traceable

Equivalent expected efficacy does not justify recording biologic treatment only by generic class when brand-level adverse-event traceability is required.

Fast response needs a stop rule

Rapid itch improvement on a JAK inhibitor is valuable but does not override infection, thrombotic or laboratory risk and formal response assessment.

08Common pitfallsFrequent interpretation and management errors.

01
Promising a newly licensed medicine without checking its current NICE disease and severity criteria.
02
Ordering a biologic panel but omitting TB exposure history, hepatitis core antibody or vaccination review.
03
Giving a live vaccine during biologic or JAK treatment without specialist timing.
04
Choosing IL-17 blockade without asking about inflammatory bowel disease or TNF blockade without neurological and heart-failure history.
05
Using a JAK inhibitor in a high-risk older smoker without establishing that no suitable alternative exists.
06
Combining a biologic with another biologic or JAK inhibitor.
07
Recording only a generic biologic name and losing brand and biosimilar traceability.
08
Continuing treatment past the appraisal checkpoint without objective benefit.