← Our teamEvidence & trials
Owen Castellanos
Reads the trial, not the landing page — and says plainly where a protocol has no evidence behind it.
Owen signs the research desk, covering the clinical literature on semaglutide, tirzepatide and the rest of the incretin class. That means what a trial was powered to show, what the effect sizes actually were, and the distance between a labeled dose and the protocols sold online. Every claim under this byline carries a citation you can open.
Coverage
- Semaglutide and tirzepatide clinical trials
- Incretin pharmacology and GLP-1 receptor agonism
- Dose titration schedules and tolerability
- Compounded versus FDA-approved drug regulation
- Evidence grading: human, animal, in-vitro
- Off-label and microdose prescribing evidence
Articles by Owen Castellanos
188 piecesShowing 1–12 of 188 articles
- GLP-1 and IBS: Why the Drug Name MattersSafety
- GLP-1 and Kidney Stones: What the Urine Studies ShowSafety
- GLP-1 and Lupus: Small Studies, Important LimitsSafety
- GLP-1 and SGLT2 Inhibitors: When Two Diabetes Drugs HelpEvidence
- GLP-1 Blood Tests: What to Ask Before and During TreatmentSafety
- Not Losing Weight on Tirzepatide? What Late Response MeansEvidence
- SURMOUNT-MAINTAIN: Can a Lower Tirzepatide Dose Hold Weight Loss?Evidence
- Ozempic and Weed: What Is Known About GLP-1s and CannabisEvidence
- GLP-1 Patches: What They Contain and Why None Is a DrugFormats
- GLP-1 Supplements and Berberine: What the Trials ShowEvidence
- How to Get a GLP-1 Prescription for Weight LossEvidence
- Wegovy Pill: Dosing, Results, Side Effects and CostEvidence
- ACHIEVE-1 Explained: Where the Oral GLP-1 Curve StopsEvidence
- Bacteriostatic Water and Reconstitution: What the Diluent Label Actually SaysSafety
- Anti-Drug Antibodies and GLP-1 Drugs: What the Labels Report and What They Never TestedEvidence
- GLP-1s and Water Pills: The Dose That Stops Being RightSafety
- GLP-1 and Difficulty Swallowing: What the Labels Actually SaySafety
- GLP-1s and Seizure Medications: Nobody Has Drawn a LevelSafety
- GLP-1s and Gout: Urate Fell, Attacks Did NotEvidence
- GLP-1 and Hiccups: On One Label, With No Number AttachedSafety
- GLP-1s and Lithium: The Interaction No Label MentionsSafety
- GLP-1 and Micronutrients: Inferred Almost Everywhere, Measured Almost NowhereSafety
- GLP-1s and the Pill: Why Only One Label Says Use BackupSafety
- GLP-1s and Psoriasis: What the One Large Trial MeasuredEvidence
- GLP-1s and Rheumatoid Arthritis: No Trial, One Chart ReviewEvidence
- GLP-1 Half-Life and Steady State: What the Labels SayFormats
- PIONEER 4 Explained: The Semaglutide Tablet Against an InjectionEvidence
- SCALE Obesity and Prediabetes Explained: Liraglutide 3.0 mgEvidence
- STEP 6 Explained: Semaglutide in Japan and South KoreaEvidence
- STEP 7 Explained: A 44-Week Clock and a Busy Placebo ArmEvidence
- STEP TEENS Explained: The 16% Is a BMI Change, Not a Weight ChangeEvidence
- SUMMIT Explained: The HFpEF Trial Powered on EventsEvidence
- SURMOUNT-5 Explained: The Head-to-Head, Read ProperlyEvidence
- SURPASS-1 Explained: Tirzepatide Alone Against PlaceboEvidence
- SURPASS-5 Explained: Tirzepatide Added to InsulinEvidence
- SURPASS-AP-Combo Explained: Tirzepatide Against InsulinEvidence
- ATTAIN-2 Explained: An Oral GLP-1 in Type 2 DiabetesEvidence
- CagriSema vs Tirzepatide: What Cannot Be ComparedEvidence
- Amylin Analogs: What the Class Has Actually ShownEvidence
- GLP-1s and Breastfeeding: What Has Actually Been MeasuredSafety
- GLP-1s and Dialysis: What the Labels Claim and What Was TestedEvidence
- GLP-1s, Fertility and IVF: The Washout and the Missing EndpointEvidence
- GLP-1 and Libido: What No Trial MeasuredEvidence
- GLP-1s and Metabolic Syndrome: A Cluster That Moves UnevenlyEvidence
- GLP-1 Muscle Cramps: A Word on No LabelEvidence
- GLP-1 and Sleep Quality: The Unnumbered EndpointEvidence
- GLP-1 and Smell Changes: The Test Moves the Other WayEvidence
- How to Read a Certificate of Analysis for a Compounded GLP-1Safety
- What a GLP-1 Telehealth Intake Actually AsksSafety
- REDEFINE 2 Explained: What CagriSema Does in Type 2 DiabetesEvidence
- STEP 9 Explained: Semaglutide and the Arthritic KneeEvidence
- SURPASS-3 Explained: Tirzepatide Against Titrated InsulinEvidence
- ATTAIN-1 Explained: 11.2% at 72 Weeks, and the Columns That ReverseEvidence
- GLP-1s, Asthma and COPD: What the Observational Data ShowsEvidence
- GLP-1s and Low Testosterone: Which Number Actually MovesEvidence
- GLP-1s and Men: What the Trials Actually MeasuredEvidence
- GLP-1s and Migraine: The Pressure Theory and Its LimitsEvidence
- GLP-1 Injection Technique: What the Labels Specify, and What They Leave OpenEvidence
- Needle Fear and GLP-1 Injections: What the Evidence MeasuresEvidence
- GLP-1 vs Liraglutide: What the Older Molecule Still HasEvidence
- GLP-1 vs Orlistat: The 37% That Applied to a Fifth of the TrialEvidence
- OASIS 1 Explained: 15% From a Tablet Nobody SellsEvidence
- Once-Monthly GLP-1 Candidates: What the Trials ShowEvidence
- Oral Tirzepatide: What Exists, and What Is Being SoldEvidence
- Retatrutide vs Tirzepatide: A Comparison That ReversesEvidence
- Rybelsus vs Injectable Semaglutide: One Molecule, Two RoutesEvidence
- SURPASS-4 Explained: A Glucose Trial People Quote for Its Heart ColumnEvidence
- SURPASS-CVOT Explained: Noninferior to a Drug That Already WorksEvidence
- GLP-1 and Blood Pressure: Real, Rented, and Not Dose-DependentEvidence
- GLP-1 and Cholesterol: Which Column Actually MovesEvidence
- Treating GLP-1 Constipation: What Has and Has Not Been TestedEvidence
- Food Noise on GLP-1 Drugs: What Has Been MeasuredEvidence
- GLP-1 and Set Point Theory: Moved, or Just Held Down?Evidence
- GLP-1 vs GIP: What the Second Receptor Really AddsEvidence
- What a Compounding Pharmacy ChargesFormats
- How GLP-1 Drugs Work, and What the Mechanism Leaves OutEvidence
- OASIS 4 Explained: The 307-Person Trial Behind the Semaglutide TabletEvidence
- REDEFINE 1 Explained: 3,417 People, and 302 in the Arm That MatteredEvidence
- STEP-HFpEF Explained: The Symptom Score That Ignored the WeightEvidence
- SURMOUNT-MMO Explained: The Tirzepatide Outcome Trial That Has Not ReportedEvidence
- Vaccines and GLP-1s: A Census of What Nobody Has MeasuredEvidence
- GLP-1 Abdominal Pain: One Reaction, Six DefinitionsEvidence
- GLP-1 Aspiration Risk: A Surrogate That Quadrupled, an Outcome That Did NotEvidence
- GLP-1s After Cancer: What the Warning Covers, and What Nobody MeasuredEvidence
- Eating Out on a GLP-1: What the Timing Data Actually ShowEvidence
- GLP-1s and HIV: A Small Literature at Half the DoseEvidence
- How Much Water on a GLP-1: The Advice With No Number Behind ItEvidence
- GLP-1 Hypoglycemia: The Population Nobody CountedEvidence
- GLP-1s and Liver Impairment: What the Labels Do and Do Not SayEvidence
- GLP-1s and Menstrual Changes: What Was Actually MeasuredEvidence
- GLP-1s and Shift Work: Mostly Extrapolation, and Which Parts Are NotEvidence
- PIONEER 6 Explained: The Composite That Missed and the Deaths That HalvedEvidence
- STRIDE Explained: 13% Further, and It Was Not the WeightEvidence
- SURPASS-2 Explained: The Head-to-Head Ran at the Diabetes DoseEvidence
- Amycretin: What the Published Trials Actually ShowEvidence
- ESSENCE Explained: An Interim Read on a Trial That Ends in 2029Evidence
- EVOKE and EVOKE+: The Alzheimer's Trials Read OutEvidence
- GLP-1 and Smoking: What the Trials FoundEvidence
- What a GLP-1 Costs Once You Reach a Maintenance DoseFormats
- GLP-1 Dose Timing: What the Labels Actually PermitSafety
- Tapering Off a GLP-1: What Has Actually Been TestedEvidence
- STEP 8 Explained: The Head-to-Head, and the Column Nobody TestedEvidence
- SURMOUNT-3 Explained: The Lifestyle Lead-In Was a FilterEvidence
- SUSTAIN-6 Explained: A Safety Trial Read as a Benefit TrialEvidence
- GLP-1s and ADHD Stimulants: What Nobody Has MeasuredSafety
- GLP-1 Ileus and Bowel Obstruction: What the Labels SayEvidence
- GLP-1, Dehydration and Kidney Injury: Reading the WarningEvidence
- GLP-1s and a History of an Eating Disorder: What Is KnownEvidence
- GLP-1 and Heart Rate: How Many Beats, and Whether It MattersEvidence
- GLP-1s and IBD: What the Crohn's and Colitis Data ShowEvidence
- GLP-1s and Tacrolimus: The Interaction That Should Matter MostEvidence
- GLP-1s and NSAIDs: The Kidney Risk Nobody Writes DownSafety
- GLP-1s and Osteoarthritis: What the Knee Trials MeasuredEvidence
- GLP-1s and Prediabetes: What Reversion Actually BuysEvidence
- GLP-1 Rash and Hypersensitivity: What the Labels RecordEvidence
- GLP-1s and Statins: Three Studies, Three DirectionsEvidence
- GLP-1 vs Contrave: The Trial That Was Stopped Before It Could AnswerEvidence
- GLP-1 vs Phentermine: The Drug That Ranked First, Then LastEvidence
- Weekly vs Daily GLP-1 Injections: What the Interval Actually BuysEvidence
- Survodutide and Mazdutide: What the Trials Show So FarEvidence
- GLP-1s and Acid Reducers: What a PPI Does to the TabletSafety
- GLP-1 Bloating: The Weakest Signal on the Whole GI TableEvidence
- GLP-1 Dry Mouth: A Ten-Fold Ratio on a 1% CountEvidence
- GLP-1 Headache: How Much Is the Drug, and How Much Is PlaceboEvidence
- GLP-1s and Insulin: The Dose Reduction the Label Asks ForSafety
- GLP-1s and Sulfonylureas: The Interaction That Reaches the HospitalSafety
- GLP-1 Vomiting: Rates by Dose, and a Ratio That InvertsEvidence
- GLP-1s and Warfarin: How Thin the Evidence Really IsSafety
- GLP-1 Needles: Length, Gauge and What Actually Reaches MuscleEvidence
- Vial or Pen: What the Error Data and the Labels SayEvidence
- STEP 3 Explained: Semaglutide Plus Thirty Counseling VisitsEvidence
- STEP 5 Explained: What the Second Year of Semaglutide BoughtEvidence
- SURMOUNT-2 Explained: Tirzepatide With Type 2 DiabetesEvidence
- SURMOUNT-OSA Explained: Two Trials, Split by the MachineEvidence
- GLP-1 Diarrhea: Rates, Molecules and the Dose ReversalEvidence
- GLP-1 Dizziness: Dehydration, Blood Pressure or Low SugarEvidence
- GLP-1 and Taste Changes: A Reward Shift, Not a Taste LossEvidence
- What Testing Found in Counterfeit GLP-1sEvidence
- Zepbound vs Mounjaro: Identical Doses, Different ApprovalsEvidence
- GLP-1 vs Metformin: The Cheap Drug's Fifteen-Year RecordEvidence
- Wegovy vs Ozempic: Same Molecule, Two Different LabelsEvidence
- GLP-1 and Fatty Liver: What the MASH Biopsies ShowedEvidence
- GLP-1 and Heart Failure: The HFpEF and HFrEF SplitEvidence
- GLP-1 vs Bariatric Surgery: What Each Route Has Been Shown to DoEvidence
- What “Not FDA-Approved” Actually MeansSafety
- GLP-1s for Adolescents: What STEP TEENS Actually ShowedEvidence
- GLP-1 for Alcohol Use Disorder: How Strong Is the Case?Evidence
- GLP-1s and Type 1 Diabetes: The Off-Label EvidenceEvidence
- GLP-1 Cost Per Pound: The Comparison Nobody RunsEvidence
- Switching From Semaglutide to Tirzepatide: The EvidenceEvidence
- SOUL Explained: Oral Semaglutide and Heart OutcomesEvidence
- STEP 1 Explained: The Trial Behind the 14.9% FigureEvidence
- SURMOUNT-1 Explained: Inside the Tirzepatide TrialEvidence
- CagriSema: What the REDEFINE Trials Actually FoundEvidence
- GLP-1 Constipation: The Mechanism Does Not Survive MeasurementEvidence
- GLP-1s and Reflux: The Risk Reverses on Half-LifeEvidence
- Orforglipron: What the Phase 3 Trials Show, and Its StatusEvidence
- Retatrutide: What the Trials Show, and Why You Cannot Buy ItEvidence
- FLOW Explained: The Semaglutide Kidney Outcomes TrialEvidence
- GLP-1s and Antidepressants: What the Subgroup Data ShowEvidence
- GLP-1s and Caffeine: What Has Actually Been StudiedSafety
- GLP-1s and Levothyroxine: The Interaction on the LabelSafety
- GLP-1s and Oral Medications: What the Interaction Trials FoundSafety
- SELECT Explained: The Semaglutide Cardiovascular TrialEvidence
- STEP 4 Explained: What Happens When Semaglutide StopsEvidence
- SURMOUNT-4 Explained: Stopping Tirzepatide, MeasuredEvidence
- GLP-1 After Bariatric Surgery: The Regain EvidenceEvidence
- GLP-1s and PCOS: What the Evidence Actually ShowsEvidence
- GLP-1 and Menopause: What the Transition Actually ChangesEvidence
- GLP-1 Doses and Acute Illness: What the Evidence Actually CoversEvidence
- “Ozempic Face”: What Imaging Measured, and What It Cannot SeparateEvidence
- Semaglutide and the Eyes: NAION and Retinopathy in Absolute NumbersSafety
- Do GLP-1s Cause Hair Loss? The Trials, and the Surgery ComparisonEvidence
- GLP-1s Before Surgery: The Fasting Guidance, RevisedSafety
- GLP-1 Telehealth: Seven Patterns Worth CheckingFormats
- Eating on a GLP-1: Protein, Appetite and the Trial DietsEvidence
- GLP-1 and Thyroid Cancer: The Warning and the DataSafety
- GLP-1 and Kidney Disease: What the FLOW Trial FoundEvidence
- GLP-1 Long Term: How Far the Evidence Actually RunsEvidence
- Semaglutide Doses Explained: 0.25 mg to 2.4 mgFormats
- Compounded vs FDA-Approved GLP-1: What to CheckSafety
- GLP-1 for Women and Men: What Actually DiffersEvidence
- GLP-1 Side Effects: What the Trials RecordedSafety
- Tirzepatide vs Semaglutide: What the Trials Actually MeasuredEvidence
- What Happens When You Stop Taking a GLP-1Evidence
- How Much Weight People Lost on Semaglutide in the TrialsEvidence
- Oral vs Injectable GLP-1: What the Tablet Trials ShowFormats
- Who Should Not Take a GLP-1: The Short List and the Long OneSafety