Medical Glossary

A 5-alpha-reductase inhibitor is a medication that blocks the conversion of testosterone to dihydrotestosterone (DHT). The class is FDA-approved for benign prostatic hyperplasia and male pattern hair loss. It includes finasteride (Type II selective) and dutasteride (Type I and Type II).

An anti-androgen is a medication that reduces or blocks androgen activity in the body. Mechanisms include reducing androgen production, blocking the androgen receptor, and inhibiting the conversion of testosterone to DHT. The category includes 5-alpha-reductase inhibitors, androgen receptor blockers, and some other agents.

Area Under the Curve (AUC) is a measure of total drug exposure over time, calculated as the integral of the plasma concentration vs time curve. AUC is used in pharmacokinetics to compare drug formulations, doses, and bioequivalence.

Asynchronous (async) telehealth is a model of remote healthcare in which the patient submits information (intake forms, photos, lab results) without a real-time video or phone consultation with the clinician. The clinician reviews and prescribes if appropriate. Most U.S. states permit async prescribing for many medications under defined conditions.

AUC, or Area Under the Curve, is a pharmacokinetic measure that quantifies total drug exposure in the bloodstream over a defined period. It represents the integral of plasma concentration versus time and is used to compare bioavailability between different formulations, doses, or administration routes. In telehealth prescribing — including ZYNDIO's compounded therapies — AUC data from published trials helps providers estimate how much active drug reaches systemic circulation and how long it remains at therapeutic levels.

Bioavailability is the fraction of an administered dose of unchanged drug that reaches systemic circulation. By definition, intravenous administration has 100% bioavailability; other routes (oral, transdermal, intramuscular) have varying bioavailability based on absorption, first-pass metabolism, and other factors.

BPC-157 (Body Protection Compound-157) is a 15-amino-acid peptide derived from human gastric juice protein, marketed in the wellness and "research peptide" space for tissue healing. It is not FDA-approved and is not currently authorized for compounding for human use.

A compounded medication is one prepared by a licensed pharmacist for a specific patient, typically because the commercially manufactured product is unavailable, the patient cannot tolerate an inactive ingredient, or a non-standard dose is clinically required. Compounded preparations are not FDA-approved as finished drug products.

Dutasteride is a dual 5-alpha reductase inhibitor that blocks both Type I and Type II isoforms of the enzyme responsible for converting testosterone into dihydrotestosterone (DHT). The FDA approved dutasteride (brand name Avodart) in 2001 for the treatment of benign prostatic hyperplasia (BPH) in adult males. By reducing DHT levels throughout the body by up to 90%, dutasteride has also been studied and used off-label for androgenetic alopecia (male pattern hair loss), though this indication has not received FDA approval. Dutasteride is available as a 0.5 mg capsule taken once daily, and compounded formulations may be prescribed by licensed providers for hair loss. Because it is more potent and has a longer half-life than finasteride, dutasteride requires careful patient selection and monitoring by a healthcare provider.

Enclomiphene is the trans-isomer of clomiphene citrate, a SERM (selective estrogen receptor modulator) used off-label for secondary hypogonadism in men. It raises endogenous testosterone by blocking estrogen feedback at the hypothalamus and pituitary, preserving fertility and testicular function unlike conventional TRT.

Finasteride is a Type II 5-alpha-reductase inhibitor FDA-approved for male pattern hair loss (1 mg, Propecia) and benign prostatic hyperplasia (5 mg, Proscar). It works by reducing dihydrotestosterone (DHT), the androgen most directly responsible for follicular miniaturization in male pattern baldness.

A GLP-1 receptor agonist is a medication that activates the glucagon-like peptide-1 receptor, mimicking the body's GLP-1 hormone. The class is FDA-approved for type 2 diabetes and chronic weight management, and includes semaglutide, liraglutide, dulaglutide, and exenatide.

A growth hormone secretagogue is a substance that stimulates the pituitary to release endogenous growth hormone. The category includes GHRH analogs (sermorelin, tesamorelin, CJC-1295) acting through the GHRH receptor, and GHRPs (ipamorelin, MK-677) acting through the ghrelin receptor pathway.

Half-life (t½) is the time required for the plasma concentration of a drug to decrease by 50%. Half-life determines dosing frequency, time to steady state, and time to drug clearance after discontinuation.

The Health Insurance Portability and Accountability Act of 1996 is the U.S. federal law that establishes data privacy and security standards for protected health information (PHI). HIPAA applies to healthcare providers, health plans, healthcare clearinghouses, and their business associates.

Liraglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist administered once daily via subcutaneous injection. The FDA approved liraglutide under the brand name Victoza for type 2 diabetes management and under the brand name Saxenda for chronic weight management in adults with obesity or overweight with at least one weight-related comorbidity. It mimics the action of naturally occurring GLP-1, a hormone that regulates blood sugar and appetite by slowing gastric emptying, enhancing insulin secretion, and reducing glucagon release. Compounded liraglutide formulations, which may be available through telehealth pharmacies like ZYNDIO, are not FDA-approved drug products and are prepared by state-licensed compounding pharmacies pursuant to a valid prescription from a licensed provider.

Minoxidil is a vasodilator originally developed to treat high blood pressure, later found to stimulate hair growth when applied topically. The FDA approved topical minoxidil for androgenetic alopecia (pattern hair loss) in men in 1988 and in women in 1991. Compounded oral minoxidil is used off-label at low doses for hair loss, but this formulation is not FDA-approved. Minoxidil works by prolonging the anagen (growth) phase of hair follicles and improving blood flow to the scalp. It is available over-the-counter in 2% and 5% topical solutions and foams, and as a prescription oral tablet through licensed providers.

mTOR inhibitors are medications that block the mechanistic target of rapamycin, a central nutrient-sensing and cell-growth regulatory pathway. The class is FDA-approved for organ transplant rejection prophylaxis and certain cancers, and is used off-label for longevity-focused interventions based on preclinical lifespan extension data.

Off-label use describes a clinically appropriate prescription of an FDA-approved medication for an indication, dose, route, or patient population not specified in the FDA-approved label. Off-label use is legal when prescribed by a licensed clinician but does not carry the FDA's affirmative finding of safety and efficacy for that specific use.

A PDE5 inhibitor is a medication that inhibits the enzyme phosphodiesterase type 5, which degrades cyclic guanosine monophosphate (cGMP) in vascular smooth muscle. The class is FDA-approved for erectile dysfunction and pulmonary arterial hypertension, and includes sildenafil, tadalafil, vardenafil, and avanafil.

Peptide therapy refers to the clinical or off-label use of short chains of amino acids (peptides) for various therapeutic purposes including growth hormone modulation, tissue healing, and metabolic effects. The clinical evidence base varies dramatically across specific peptides — from FDA-approved indications to research-only.

Prescription titration is the structured stepwise increase of a medication dose over time, used to manage tolerability while reaching a target therapeutic dose. Titration schedules are typically specified in the FDA-approved label and are particularly important for medications like GLP-1 agonists and TRT.

Protected Health Information (PHI) is individually identifiable health information held or transmitted by a HIPAA-covered entity or business associate. PHI is governed by the HIPAA Privacy Rule and includes any information that can be used to identify an individual in connection with their health, healthcare, or healthcare payment.

Protected Health Information (PHI) refers to any individually identifiable health information that is created, received, maintained, or transmitted by a covered entity or business associate under the Health Insurance Portability and Accountability Act (HIPAA). PHI includes 18 specific identifiers defined by the HIPAA Privacy Rule, ranging from names and Social Security numbers to prescription records and payment history. When you consult with a licensed provider through ZYNDIO's telehealth platform, discuss medical history, receive a prescription for compounded semaglutide or finasteride, or process payment information, all of that data qualifies as PHI and receives federal privacy protection. Understanding PHI matters because it defines what information healthcare entities must safeguard, how they can use or disclose it, and what rights you have to access and control your own health records.

Rapamycin (sirolimus) is an mTOR inhibitor FDA-approved for organ transplant rejection prophylaxis and several other niche indications. It is widely used off-label at low weekly doses for longevity-focused interventions, based on extensive preclinical lifespan extension data in animals — though human longevity outcomes are not established.

A selective estrogen receptor modulator (SERM) is a medication that selectively activates or blocks the estrogen receptor depending on the tissue. SERMs include tamoxifen (breast cancer), raloxifene (osteoporosis), and clomiphene/enclomiphene (ovulation induction in women, secondary hypogonadism in men).

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist FDA-approved for type 2 diabetes (Ozempic, Rybelsus) and chronic weight management (Wegovy). It is administered as a once-weekly subcutaneous injection or as a daily oral tablet, and acts by slowing gastric emptying, increasing satiety signaling, and improving glucose-dependent insulin secretion.

A selective estrogen receptor modulator (SERM) is a class of compounds that binds to estrogen receptors in the body and acts as an agonist (activator) in some tissues while acting as an antagonist (blocker) in others. This tissue-selective activity distinguishes SERMs from estrogen itself, which activates receptors broadly. Clinically relevant SERMs include tamoxifen and raloxifene (used in breast cancer and osteoporosis, respectively), as well as clomiphene and enclomiphene (used off-label in male fertility and hypogonadism). SERMs are prescribed and monitored by licensed healthcare providers; none are available over-the-counter.

Sermorelin is a 29-amino-acid GHRH (growth hormone releasing hormone) analog that stimulates the pituitary to release endogenous growth hormone. It was FDA-approved in 1990 for pediatric growth hormone deficiency but the branded product was withdrawn in 2008. It is currently available through compounding pharmacies for off-label adult use.

Sildenafil is a short-acting PDE5 inhibitor FDA-approved for erectile dysfunction (Viagra) and pulmonary arterial hypertension (Revatio). Its onset is 30-60 minutes and clinical window is approximately 4 hours, with absorption sensitive to high-fat meals.

Synchronous telehealth is a model of remote healthcare in which the patient and clinician interact in real time, typically via video or phone. Required for some clinical scenarios and controlled substance prescribing under federal and state rules.

Tadalafil is a long-acting PDE5 inhibitor FDA-approved for erectile dysfunction (Cialis) and benign prostatic hyperplasia. Its 17.5-hour half-life produces a 24-36 hour clinical window, supporting both on-demand and daily low-dose dosing schedules.

Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist administered by weekly subcutaneous injection. The FDA approved tirzepatide for type 2 diabetes management in 2022 under the brand name Mounjaro, and for chronic weight management in adults with obesity or overweight with weight-related comorbidities in 2023 under the brand name Zepbound. Compounded tirzepatide formulations, which are prepared by state-licensed compounding pharmacies pursuant to valid prescriptions, are not FDA-approved drug products and differ from the branded versions in formulation, dosing, and regulatory oversight.