Lesson
Read Hair Loss Through the Follicle Cycle
Hair loss can reflect shortened growth, synchronized rest, matrix injury, shaft breakage, miniaturization, or follicular destruction. The cycle explains why cause and shedding may be separated by months.
- Anagen
- Catagen
- Telogen
- Exogen
- Miniaturization
Long duration defines scalp length
Matrix activity contracts
The club hair remains retained
Shedding can lag a trigger by months
Follow active growth
Anagen is the long growth phase. Matrix cells divide rapidly, so severe metabolic stress and cytotoxic therapy can interrupt growth quickly.
Account for delayed shedding
A trigger can push follicles into telogen, but visible shedding often begins weeks to months later. The delay can obscure the causal event.
Separate shedding from breakage
A shed club hair differs from a broken shaft. Chemical processing, heat, friction, tension, and structural disease can reduce length without releasing the follicle.
Recognize miniaturization and destruction
Androgenetic alopecia gradually converts terminal hairs into finer hairs. Scarring alopecia destroys follicles and may erase follicular openings, making delay costly.
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Lesson
Classify the Pattern Before Treating
Tempo, geometry, inflammation, symptoms, breakage, follicular openings, nail findings, body-hair involvement, exposures, and systemic context define the differential.
- Patterned thinning
- Diffuse shedding
- Patchy loss
- Scalp inflammation
- Follicular openings
Central, crown, or frontal geometry
Trigger history is central
Examine hairs, skin, and nails
Early treatment protects remaining follicles
Build the chronology
Document onset, progression, shedding, illness, surgery, childbirth, weight change, diet, stress, medication changes, styling, family history, and associated symptoms.
Examine beyond density
Inspect scalp scale, erythema, pigment, pustules, scarring, hair caliber, broken hairs, pull pattern, brows, lashes, body hair, and nails.
Order targeted tests
Laboratory testing should answer a clinical hypothesis such as thyroid disease, anemia, iron deficiency, nutritional deficiency, or androgen excess. Broad supplement panels without context create noise.
Escalate red flags
Pain, burning, pustules, boggy inflammation, rapid focal loss, broken hairs, eyebrow loss, absent follicular openings, or systemic illness needs diagnostic evaluation.
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Lesson
Connect DHT to Follicular Miniaturization
Androgenetic alopecia is genetically patterned and progressive. Local androgen metabolism and follicular sensitivity shorten anagen and produce finer, shorter hairs.
- Five alpha reductase
- DHT
- Androgen receptor
- Miniaturization
- Pattern
Five alpha reductase supplies the signal
Susceptibility differs by follicle
Terminal hairs become finer
Maintenance preserves response
Map the enzyme signal
Five alpha reductase converts testosterone to dihydrotestosterone. Finasteride preferentially inhibits the type 2 isoenzyme and lowers DHT signaling in susceptible follicles.
Read pattern without stereotype
Men often develop frontal, temporal, vertex, or crown loss. Women often show central thinning or a widening part, but pattern alone does not replace examination and endocrine context.
Set realistic goals
Treatment can slow progression and increase thickness, but complete restoration is uncommon. Earlier miniaturization is more reversible than long-standing follicular loss.
Separate approved and clinician-directed use
Topical minoxidil has labeled products for men and women. Finasteride 1 mg is labeled for male pattern hair loss in men only, while other uses require specialist judgment.
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Lesson
Use Topical Minoxidil as a Product, Not a Class Shortcut
Topical minoxidil requires follicular activation to minoxidil sulfate and sustained scalp exposure. Strength, vehicle, labeled population, dose, and schedule differ among products.
- Minoxidil sulfate
- Potassium channels
- Solution
- Foam
- Continued use
Product-specific dose and schedule
Follicular sulfotransferase matters
Experimental support; not a complete clinical explanation
Stopping removes the benefit
Connect activation to variability
Sulfation produces the active metabolite minoxidil sulfate. Human follicle experiments support a role for ATP-sensitive potassium channels, but the complete clinical growth mechanism remains incompletely defined. Do not equate a proposed pathway with guaranteed response.
Follow the container
Men’s 5% solution: 1 mL twice daily to the vertex; stop and consult a clinician if no regrowth at four months. Women’s Rogaine 5% foam: half a capful once daily; stop and seek advice if no regrowth at six months. Do not transfer directions across formulations.
Compare the other formulations
Women’s Rogaine 2% solution uses 1 mL twice daily, with a four-month nonresponse deadline. Men’s Rogaine 5% foam uses half a capful twice daily, also with a four-month deadline. A foam capful is not a dropper volume. Check the exact product and intended population; the women’s 5% foam once-daily schedule does not apply to all 5% products.
Decide whether self-care fits
These labels exclude patients younger than 18, sudden or patchy loss, an unknown cause, no family history, an inflamed scalp, or concurrent scalp medicines. The reviewed women’s products also exclude postpartum loss. Heart disease requires prior medical advice; pregnancy or breastfeeding requires an alternative plan.
Prepare for time and shedding
Results take months and may begin with a temporary increase in shedding as follicles cycle. Continued use is needed to maintain benefit; more product does not improve results.
Screen safety and technique
Apply to dry scalp skin, wash hands, allow drying, avoid eye or body exposure, and review flammability. Stop and seek care for chest pain, rapid heartbeat, faintness, dizziness, unexplained weight gain, edema, scalp redness or irritation, or unwanted facial hair.
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Lesson
Select Systemic and Procedural Options Deliberately
Finasteride, spironolactone, low-dose oral minoxidil, dutasteride, devices, procedures, and transplantation differ in approval, mechanism, reproductive risk, monitoring, and evidence.
- Finasteride
- Spironolactone
- Oral minoxidil
- Off-label use
- Hair transplant
Lowers scalp and serum DHT
Selected patients need potassium review
Pressure, pulse, edema, and hair growth matter
Evidence and candidacy differ
Use finasteride precisely
Propecia is finasteride 1 mg daily for male pattern hair loss in men. Benefit generally requires at least three months; stopping reverses benefit within twelve months. Check for duplicate finasteride prescriptions. Bitemporal recession efficacy is unestablished.
Counsel reproductive and sexual safety
Pregnancy contraindicates finasteride. Anyone pregnant or potentially pregnant must avoid crushed or broken tablets; intact coating prevents contact during normal handling. Wash accidental damaged-tablet contact promptly with soap and water. Counsel about sexual symptoms, including reports persisting after discontinuation, fertility concerns, breast changes, depression and suicidal thoughts; urgent symptoms need immediate care.
Interpret prostate monitoring correctly
Finasteride lowers PSA. Evaluate a confirmed rise from the treatment nadir even within the untreated reference range. The high-grade prostate-cancer warning derives from prevention trials using finasteride 5 mg or dutasteride 0.5 mg; it is not a measured 1 mg hair-loss trial rate. Cross-trial sexual adverse-event rates do not establish a simple dose comparison.
Treat off-label therapy as off-label
Spironolactone and low-dose oral minoxidil are clinician-directed options for selected patients. Review potassium, kidney function, blood pressure, pulse, edema, hypertrichosis, pregnancy potential, and interacting therapy as appropriate.
Plan spironolactone safety
Hair-loss use is off-label. Avoid use in pregnancy. Hyperkalemia, Addison disease and concomitant eplerenone are label contraindications. Review potassium supplements, salt substitutes, ACE inhibitors, ARBs, NSAIDs and trimethoprim. The label calls for potassium testing within one week of initiation or titration and regularly thereafter, with closer review for renal impairment or interacting therapy. Discuss menstrual changes, breast symptoms and hypotension.
Respect oral minoxidil exposure
The tablet label is for difficult-to-control hypertension and carries a boxed warning for pericardial effusion that can progress to tamponade and for worsening angina. Hair-loss use is off-label. Review cardiovascular history, blood pressure, pulse, edema and other medicines; lower doses do not erase systemic risk. Do not automatically copy the hypertension regimen into a hair-loss plan.
Put dutasteride evidence in context
Dutasteride inhibits type 1 and type 2 five alpha reductase. Its US indication is BPH; hair-loss use is off-label. A 24-week randomized trial in 917 men aged 20 to 50 found better hair-count and width outcomes with 0.5 mg daily than finasteride 1 mg daily. That duration does not establish long-term comparative safety or a universal preferred treatment.
Counsel dutasteride separately
Pregnancy contraindicates use. Anyone pregnant or potentially pregnant should avoid handling the capsules; wash leaking-capsule contact promptly with soap and water. Swallow capsules whole. Avoid blood donation during treatment and for at least six months afterward. Discuss sexual and breast symptoms, uncertain fertility effects, PSA suppression and persistent exposure after stopping. Review chronic potent CYP3A4 inhibitors.
Place procedures honestly
Low-level light devices, platelet-rich plasma, microneedling, and transplantation have different evidence, cost, burden, permanence, and candidacy. They should not replace diagnosis.
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Lesson
Trace Diffuse Shedding Back to Its Trigger
Telogen effluvium produces delayed diffuse shedding after a physiologic or emotional trigger. Anagen effluvium follows rapid matrix injury. Medication attribution requires timing and alternatives.
- Telogen effluvium
- Anagen effluvium
- Postpartum shedding
- Medication timeline
- Nutritional deficiency
Often begins months after a stressor
Chemotherapy is a classic cause
Do not stop essential therapy blindly
Regrowth still takes time
Recognize telogen timing
Fever, surgery, childbirth, major illness, rapid weight loss, nutritional stress, endocrine change, and severe psychological stress can synchronize follicles into telogen. Shedding often starts two to three months later.
Recognize anagen injury
Cytotoxic chemotherapy and other severe matrix insults can produce rapid shedding during active growth. Timing and the treatment regimen distinguish this from telogen effluvium.
Audit medications
Heparin and warfarin labeling includes alopecia reports. Retinoids, lithium, valproate, some endocrine therapies and other drugs can also contribute. Establish start, stop, dose, dechallenge, competing causes, and necessity before changing treatment.
Include endocrine and immune therapies
Hair-loss reports also appear in labeling for clomiphene, hydroxychloroquine, peginterferon alfa-2a and some levonorgestrel-containing contraceptives. Starting, changing or stopping hormonal therapy can complicate the timeline. A spontaneous adverse-event report does not supply a reliable incidence or establish individual causality. Do not stop contraception or essential immune therapy without a coordinated alternative.
Interpret a medication list carefully
Spironolactone illustrates why an adverse-event list is not a diagnosis: alopecia is reported in its label, yet it is also used off-label for selected patterned loss. A reported event does not establish the drug caused a particular patient’s shedding. Reconcile the indication, timeline and alternative causes with the prescriber.
Investigate endocrine and inflammatory context
Thyroid disease, including hypothyroidism, can contribute to thinning; treatment should address the confirmed disorder. Patterned thinning becomes more common after menopause, but age or menopause alone does not establish the diagnosis. Lupus can cause hair loss through different processes: inflamed, scaly discoid lesions may scar permanently and need prompt evaluation rather than a routine shedding plan.
Treat deficiencies, not marketing
Assess nutritional intake and test for suspected deficiencies, such as iron, zinc or vitamin D, when clinically indicated. Treat a confirmed deficiency without promising regrowth from supplements in a nutritionally replete patient. Excess vitamin A or selenium can itself cause hair loss; biotin can interfere with laboratory assays.
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Lesson
Treat Autoimmune Follicle Attack by Extent and Risk
Alopecia areata is a nonscarring autoimmune disorder that can involve scalp, brows, lashes, body hair, and nails. Extent, duration, age, and burden guide local or systemic therapy.
- Exclamation hairs
- Nail pitting
- Intralesional corticosteroids
- JAK inhibitors
- SALT
Nails and other body hair add evidence
Extent and age guide delivery
Severe disease has approved options
Immune modulation requires a safety system
Recognize the autoimmune pattern
Smooth patches, exclamation-point hairs, nail pitting, ophiasis, eyebrow or eyelash loss, and rapid progression can support alopecia areata. Thyroid and other autoimmune context may matter.
Measure scalp loss and broader burden
The Severity of Alopecia Tool (SALT) estimates the percentage of scalp hair lost: lower scores represent less loss. A SALT score of 20 means about 20% scalp hair loss, not 20% regrowth. Record eyebrow, eyelash, body-hair and psychosocial effects separately; scalp coverage does not capture the whole disease burden.
Treat limited disease locally
Observation can be reasonable for selected short-duration limited disease. Intralesional corticosteroids are commonly used for a few adult patches, while topical strategies may fit children or patients avoiding injections. Monitor corticosteroid-treated skin for local atrophy and pigment changes; injection site, volume and technique matter.
Know the approved systemic options
Current approved JAK inhibitors include baricitinib and deuruxolitinib for adults with severe disease, and ritlecitinib for adults and adolescents at least 12 years old with severe disease.
Consider specialist alternatives
Contact immunotherapy deliberately produces a controlled local skin reaction under dermatology supervision. Anthralin and other immune-directed treatments may fit selected patients. Clinician-directed minoxidil can support regrowth in alopecia areata, including selected children, but this is distinct from labeled adult OTC self-care. Do not copy those off-label schedules onto OTC packaging instructions.
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Lesson
Choose and Monitor the Exact JAK Inhibitor
Severe alopecia areata has several oral treatment options, each with its own dose, eligibility rules and safety monitoring.
- Baricitinib
- Ritlecitinib
- Deuruxolitinib
- Genotype
- Blood counts
Check OAT3 interactions
Distinguish platelet start and stop thresholds
Screen inhibitors before treatment
Use the selected product label
Dose baricitinib for alopecia
Olumiant starts at 2 mg daily; inadequate response can justify 4 mg. Near-total or total scalp loss may warrant starting at 4 mg; reduce to 2 mg after adequate response. For eGFR 30 to below 60 mL/min/1.73 m², halve the selected dose; below 30, use is not recommended. Severe hepatic impairment also precludes recommended use. Strong OAT3 inhibitors such as probenecid require dose review: 4 becomes 2 mg, 2 becomes 1 mg; at 1 mg, consider stopping probenecid.
Distinguish ritlecitinib administration
Litfulo is 50 mg daily from age 12 for severe alopecia areata. Swallow the capsule whole. Take a missed dose unless fewer than eight hours remain before the next. Severe hepatic impairment is not recommended. Avoid strong CYP3A inducers; review sensitive CYP3A and CYP1A2 substrates for increased exposure.
Distinguish ritlecitinib laboratory rules
Before starting, ALC must be at least 500/mm³ and platelets at least 100,000/mm³. Recheck at four weeks and subsequently as indicated. Interrupt for ALC below 500 and resume after it rises above 500; discontinue for platelets below 50,000/mm³. Evaluate liver tests at baseline and thereafter; hold if drug-induced injury is suspected. Ingredient hypersensitivity contraindicates treatment.
Counsel ritlecitinib safety and expectations
Headache, diarrhea, acne and rash are among reported adverse reactions. Serious allergy requires stopping treatment and immediate care; possible thrombosis requires interruption and urgent evaluation. Arrange periodic skin examinations. Trials included experimental loading regimens, but the approved regimen is 50 mg daily without a loading dose. A response endpoint at 24 weeks is not a promise that every patient regrows hair.
Screen before deuruxolitinib
Leqselvi is 8 mg twice daily for adults with severe alopecia areata. Obtain CYP2C9 genotype first: poor metabolizers and concurrent moderate or strong CYP2C9 inhibitors are contraindications. Review interactions before every new medicine; skip a missed dose.
Monitor deuruxolitinib specifically
Check CBC and lipids before and during therapy. Do not start, or interrupt treatment, for ALC below 500/mm³, ANC below 1,000/mm³, or hemoglobin below 8 g/dL; resume only after recovery to at least those thresholds. Control serious infections before resuming. The June 2026 label advises considering more glucose monitoring in diabetes because hypoglycemia has been reported with JAK inhibitors.
Counsel deuruxolitinib beyond laboratory tests
Headache, acne, respiratory symptoms and CPK elevations were reported in trials. New abdominal pain or related systemic symptoms require immediate evaluation for possible perforation. Arrange periodic skin examinations and urgent assessment of possible thrombosis. The 12 mg twice-daily research dose is not approved; do not increase beyond the labeled 8 mg twice-daily regimen by copying a trial arm.
Schedule baricitinib monitoring
For alopecia, avoid starting or interrupt for ALC below 500/mm³, ANC below 1,000/mm³ or hemoglobin below 8 g/dL; resume after recovery to at least those values. Assess CBC and liver tests before and during treatment; check lipids at about 12 weeks. These are not the COVID-19 blood-count rules.
Check deuruxolitinib organ function and inducers
Use is not recommended with eGFR below 30 mL/min or Child-Pugh C hepatic impairment. Mild or moderate renal or hepatic impairment needs no dose adjustment. Avoid strong CYP3A4 inducers and moderate or strong CYP2C9 inducers because exposure can fall.
Plan pregnancy and infant feeding
Discuss pregnancy intentions and potential fetal risk before treatment. Do not breastfeed during any of these therapies. After the last dose, the labeled avoidance interval is four days for baricitinib, approximately fourteen hours for ritlecitinib and one day for deuruxolitinib. These breastfeeding intervals do not establish contraception washouts.
Act on baricitinib warning signs
Screen for viral hepatitis and treat latent tuberculosis before starting. Interrupt treatment for shingles until it resolves. New severe abdominal symptoms need prompt evaluation for perforation, especially with a diverticulitis history. Stop and urgently assess suspected thrombosis or serious hypersensitivity; discontinue after myocardial infarction or stroke. Consider smoking history in cardiovascular and cancer risk assessment, and arrange periodic skin examinations for patients at increased skin-cancer risk.
Build JAK safety
Assess tuberculosis, other infection risks, vaccination, malignancy, cardiovascular and thrombotic history before selecting treatment. Avoid live vaccines and combining therapy with other JAK inhibitors or potent immunosuppression; check the exact product limitations. Arrange urgent evaluation for possible serious infection or thrombosis. The comparative cardiovascular, cancer and mortality warnings draw on another JAK inhibitor studied in higher-risk rheumatoid arthritis patients; do not present those rates as measured alopecia outcomes. Current labels also advise considering more glucose monitoring in patients with diabetes.
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Lesson
Protect the Follicle Before Loss Becomes Permanent
Traction, inflammatory scarring alopecias, and tinea capitis can initially resemble common thinning but require cause-specific intervention.
- Traction alopecia
- CCCA
- Frontal fibrosing alopecia
- Tinea capitis
- Biopsy
Early change can prevent permanence
Symptoms can precede visible loss
Systemic antifungal exposure is required
Biopsy or culture may define treatment
Interrupt traction
Tight braids, locs, ponytails, extensions, adhesives, and repeated edge tension can cause early reversible loss and later scarring. Pain, bumps, and broken hairs are warning signs.
Recognize CCCA
Central centrifugal cicatricial alopecia often begins near the crown and disproportionately affects Black women. Tenderness, itch, burning, breakage, or central thinning deserves early dermatologic assessment. Biopsy may establish the diagnosis. Treatment targets inflammation, often with corticosteroids or other specialist-selected agents; minoxidil alone is insufficient. CCCA and traction or patterned loss can coexist.
Recognize frontal fibrosing alopecia
A receding frontal hairline, eyebrow loss, facial papules, perifollicular scale, itch, or pain can signal an inflammatory scarring disorder that needs treatment to stabilize progression.
Treat tinea through the follicle
Scalp scale with broken hairs, patchy alopecia, nodes, pustules, or kerion can be fungal infection. Systemic antifungal therapy is required; shampoo alone is adjunctive. Corticosteroid monotherapy can worsen or mask fungal infection.
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Lesson
Treat Eyelash Thinning Safely
Eyelash treatment requires its own application technique and eye-safety assessment.
- Bimatoprost
- Upper lid
- Pigmentation
- Eye pressure
Investigate the cause
Demonstrate technique
Coordinate the plan
Follow changing symptoms
Apply Latisse 0.03% correctly
Each evening, clean the face and remove makeup and lenses. Place one drop on the supplied applicator; brush the upper lash base only. Blot runoff. Use a new applicator for the other eyelid; discard both. Wait 15 minutes before reinserting lenses.
Coordinate eye treatment
With glaucoma prostaglandins, consult the physician and monitor pressure: concurrent use can reduce pressure-lowering benefit. Ingredient allergy contraindicates use; inflammation and macular-edema risks need review.
Assess pregnancy and infant feeding
Adequate controlled pregnancy studies are unavailable. The label permits use during pregnancy only when expected benefit outweighs fetal risk; cosmetic intent alone does not establish that balance. Human milk exposure is unknown. Discuss maternal need, breastfeeding benefits and possible infant effects with the prescriber instead of assuming that topical use means no systemic exposure.
Discuss changes and follow-up
Iris darkening may persist; lid darkening may reverse. Irritation, unwanted hair and periorbital changes can occur. New eye symptoms require assessment. Benefit fades after stopping; extra applications do not accelerate growth.
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Lesson
Measure What Changes and Support the Person
Hair treatment takes months, response is variable, and appearance burden can be substantial. Standardized follow-up and psychosocial support are part of clinical care.
- Standardized photography
- Shedding
- Adherence
- Safety monitoring
- Camouflage and support
Anchor future comparisons
Use the same site and lighting
Reproductive and systemic risk vary
Appearance-related burden is clinical
Create a reproducible baseline
Record diagnosis, distribution, density, part width, hair caliber, symptoms, shedding, treatment, styling, and standardized photographs with consistent lighting and positioning.
Use realistic timelines
Set a treatment-specific response deadline and review safety earlier. OTC minoxidil nonresponse instructions take precedence over a general months-long trial; do not continue indefinitely without reassessing the diagnosis and product directions.
Monitor the exact treatment
Topical irritation, blood pressure, pulse, edema, potassium, kidney function, CBC, lipids, liver tests, infection, reproductive risk, mood, sexual effects, and PSA matter selectively, not universally.
Treat psychosocial burden
Camouflage, fibers, wigs, scalp prostheses, styling support, counseling, and peer resources can improve function while medical treatment proceeds or when regrowth is limited.
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Module practice
Check the connections.
Each attempt draws 10 questions from the complete 127 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Core source material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.
- Oral Versus Topical Minoxidil: 24-Week Randomized Trial
- DailyMed Kenalog-10 Intralesional Safety
- AAD Hair-Loss Causes
- AAD Female Pattern Hair Loss
- AAD Lupus Skin and Hair Findings
- DailyMed Clomiphene Adverse Events
- DailyMed Hydroxychloroquine Adverse Events
- DailyMed Peginterferon Alfa-2a Adverse Events
- DailyMed Levonorgestrel/Ethinyl Estradiol Reports
- AAD Frontal Fibrosing Alopecia Signs
- AAD Traction Alopecia
- AAD Delayed Hair Shedding
- DailyMed Avodart Dutasteride Safety
- Dutasteride Hair-Loss Trial: 24-Week Evidence
- DailyMed Women’s Rogaine 2% Solution
- DailyMed Men’s Rogaine 5% Foam
- DailyMed Spironolactone Safety
- DailyMed Oral Minoxidil Safety
- FDA Biotin and Laboratory Interference
- AAD CCCA Diagnosis and Treatment
- CDC Ringworm Treatment
- Human Follicle Potassium-Channel Experiments
- DailyMed Women’s Rogaine 5% Foam
- DailyMed Latisse Prescribing Information
- AAD Hair Loss Diagnosis and Treatment
- AAD Types of Hair Loss
- AAD Male Pattern Hair Loss Treatment
- AAD Alopecia Areata Diagnosis and Treatment
- DailyMed Minoxidil Topical Solution 5 Percent
- DailyMed Propecia Finasteride 1 mg
- DailyMed Olumiant Baricitinib
- DailyMed Litfulo Ritlecitinib
- DailyMed Leqselvi Deuruxolitinib