Per clinical trial reports + patient forums + the small body of healthy-volunteer studies:

Onset:

• Sleep effects: within 3-7 days. Sleep onset latency reductions reported as soon as the first night for some users; consolidation of sleep continuity within a week. PSG data shows acute SWS increases.
• Mood effects: 2-4 weeks for the antidepressant lift to fully appear (typical antidepressant timeline).
• Anxiolytic effects: 1-3 weeks for GAD symptom improvement.
• Anhedonia / motivation lift: weeks 2-3.

Peak / steady-state experience (responders, 25-50 mg evening dose):

• Cleaner sleep onset — gentle drowsiness ~30-60 min after dose, not the GABAergic mush of Z-drugs / phenibut, not the antihistamine fog of trazodone/mirtazapine
• Deeper, more consolidated sleep — fewer middle-of-night awakenings, more SWS subjectively
• No morning grogginess — half-life ~1-2 hr means it's gone by wake-up. This is the standout feature for Dylan's use case.
• Mood-bright daytime tone — lift in motivation, return of pleasure/interest, generally described as "brighter without being stimulated"
• Reduced anxiety baseline — particularly somatic anxiety, ruminative worry
• Vivid dreams — common, especially first 1-2 weeks; often fades; some users find this pleasant, some annoying
• Phase-advance over weeks — late chronotypes report bedtime drifting earlier when agomelatine is dosed at consistent target bedtime

Non-responder profile:

• Roughly 30-40% of clinical trial subjects don't separate from placebo
• Common pattern: 2-3 weeks of trial, no meaningful sleep or mood change, GI side effects modest but persistent
• CYP1A2 ultra-rapid metabolizers (high-inducibility *1F/*1B carriers) may be functional non-responders due to subtherapeutic exposure

Side effect signature in responders:

• Mild GI upset (nausea ~7%, dry mouth, occasional diarrhea) — usually tolerated, fades 2-4 weeks
• Headache ~7-10% — first-week phenomenon
• No sexual dysfunction — major differentiator from SSRIs
• No weight gain or loss — comparable to placebo, much cleaner than mirtazapine
• No discontinuation syndrome — can be stopped abruptly without taper (rare property among antidepressants)

The narrative users tell: "It's like my normal sleep returned and the noise turned down. I forget I'm taking it." This is the consensus subjective signature when it works.

• Tolerance buildup: minimal to none. Agomelatine doesn't produce classical pharmacological tolerance. The MT1/MT2 receptors don't desensitize meaningfully on chronic dosing in the way that, say, GABA-A receptors do with benzos. The 5-HT2C antagonism also doesn't drive obvious receptor up/downregulation.
• Therapeutic poop-out (tachyphylaxis): Small minority of users experience loss of efficacy after months/years — common to most antidepressants, not agomelatine-specific.
• Recommended cycling: None. Designed for steady-state daily use.
• Reset protocol: N/A. If poop-out emerges, switch class.
• Discontinuation: No taper required. Stop abruptly without discontinuation syndrome — this is one of agomelatine's most distinctive properties and a major differentiator from SSRIs/SNRIs (which can have prolonged discontinuation syndromes). For someone using agomelatine purely for chronotype migration (Dylan-archetype hypothetical), the ability to stop cleanly once the goal is achieved is a meaningful feature.

Synergistic with

• morning bright light (10,000 lux 30 min on wake) — agomelatine pulls evening side of the circadian cycle, light pulls morning side. Combined zeitgeber effect is stronger for phase-advance than either alone. Standard protocol in DSPD trials.
• low-dose melatonin (0.3-0.5 mg, ~5 hr pre-target-bedtime) — different mechanism timing. Melatonin at this dose acts as a phase-shift signal on the circadian clock; agomelatine at bedtime acts as the sleep-promoting signal. They're complementary, not redundant. Note: do NOT use high-dose melatonin (3-10 mg) with agomelatine — that's pharmacological flooding of the same MT receptors agomelatine is hitting, with no added phase-shift benefit.
• l-tryptophan 1 g pre-bed — feeds the upstream serotonin/melatonin pathway. No direct PK conflict (tryptophan is not CYP-metabolized). Stack-coherent for late-chronotype + sleep onset use case. For Dylan, this is the V5 stack-compatible pairing if he ever adds agomelatine.
• CBT for insomnia / sleep restriction therapy — Inoue 2022 DSPD trial used agomelatine + CBT; behavioral component matters.
• V4 core (DHA, magnesium glycinate, citicoline, NAC, PS, curcumin, rhodiola, theanine, D3+K2, beta-alanine, vitamin C): All safe co-administration; no PK conflicts.

Avoid stacking with

Absolute contraindications (do not combine):

• Fluvoxamine (Luvox) — strong CYP1A2 inhibitor, 60-fold (12-412×) increase in agomelatine AUC. Massive overdose risk. Hard contraindication.
• Ciprofloxacin and other potent CYP1A2 inhibitors (enoxacin, oral contraceptives in some interpretations) — EU label flags as contraindication. Note: practical pharmacology suggests ciprofloxacin's CYP1A2 inhibition at therapeutic doses is moderate, not as severe as fluvoxamine — but the EU label is conservative and treats it as contraindicated.

Avoid / use with caution:

• Other moderate CYP1A2 inhibitors: Norfloxacin, mexiletine, propafenone, vemurafenib, theophylline, methoxsalen — substantial agomelatine exposure increases possible
• Estrogens / oral contraceptives — moderate CYP1A2 inhibition; case-by-case assessment
• Heavy smoking — opposite direction, induces CYP1A2 and reduces agomelatine exposure (potential underdosing)
• Other hepatotoxic drugs — additive liver risk: acetaminophen at high doses, methotrexate, isoniazid, valproate, niacin (high-dose), some statins
• Heavy alcohol — additive hepatotoxicity
• L-tryptophan or 5-HTP at very high doses (>5 g/day) — theoretical 5-HT excess via 5-HT2C unmasking; not a real clinical concern at supplement doses (1-2 g tryptophan), but flag for awareness
• MAOIs (phenelzine, tranylcypromine, isocarboxazid): Theoretical concern; combination not well-studied. Standard antidepressant washout if switching.
• Tramadol, dextromethorphan in cough syrups: Modest serotonergic concern; agomelatine's lack of reuptake inhibition means risk is lower than SSRI combinations, but caution sensible.

Neutral / safe co-administration

• All V4 stack components (DHA, magtein, citicoline, NAC, PS, magnesium glycinate, curcumin phytosome, rhodiola, theanine, D3+K2, beta-alanine, vitamin C) — no PK or PD conflicts. CYP1A2 effect of curcumin is mild; not clinically meaningful in this context.
• Modafinil 100 mg AM — different mechanism (orexin/histamine wake systems vs MT/5-HT2C), opposite circadian leg (wake vs sleep), no PK conflict. AM modafinil + PM agomelatine is mechanistically clean. Modafinil is a weak CYP1A2 inducer at high doses but the effect is mild.
• Bromantane, Adamax / Semax, ALCAR — all AM, no overlap.
• Bupropion — no direct PK overlap (different CYPs), no shared mechanism conflict; theoretically synergistic for anhedonia/motivation since both lift cortical DA via different mechanisms (bupropion DAT/NET inhibition, agomelatine 5-HT2C disinhibition). Not formally studied; consider with prescriber sign-off.
• Selegiline 1-2.5 mg/day — MAO-B selective at this dose, no meaningful interaction expected. Higher selegiline doses (≥10 mg) trigger MAOI-class concerns; stack with caution.
• Creatine — no interaction.
• Caffeine — caffeine is also a CYP1A2 substrate, not an inhibitor — no agomelatine-relevant interaction. (Note: heavy caffeine intake doesn't induce CYP1A2 enough to matter clinically.)

The CYP1A2 axis is the primary interaction surface and matters more than for most antidepressants.

CYP enzymes induced/inhibited by agomelatine: Agomelatine itself does not induce or inhibit clinically important CYPs at therapeutic doses — so other drugs are not affected by agomelatine. The interaction direction is one-way: things affect agomelatine, agomelatine doesn't affect things.

Hormonal contraceptives: No significant impact on contraceptive efficacy; agomelatine doesn't induce CYP3A4. (OCP may modestly raise agomelatine levels via mild CYP1A2 inhibition — direction is toward slightly higher agomelatine exposure, not loss of contraceptive effect.)

Agomelatine has unusually variable interindividual pharmacokinetics — coefficient of variation in AUC is reported as high as 60-100% across subjects. CYP1A2 polymorphisms account for a substantial fraction of this variability.

CYP1A2 (90% of agomelatine metabolism — the dominant axis):

• CYP1A2*1C (rs2069514, -3860G>A): Reduced-activity allele. Carriers have lower clearance, higher agomelatine plasma levels at standard doses. Possible elevated hepatotoxicity risk (one published case report directly attributed liver injury to *1C carrier status — Wang 2021 Medicine).
• *CYP1A21F (rs762551, -163C>A) and 1B variants:* High inducibility alleles. Carriers have higher CYP1A2 activity in the presence of inducers (smoking, omeprazole, polycyclic aromatic hydrocarbons), so they can have markedly reduced agomelatine exposure under inducing conditions → potential functional non-response.
• rs2470890, rs2472304: Additional SNPs associated with agomelatine PK variability per Saiz-Rodríguez 2019.
• 23andMe coverage: rs762551 (the main *1F/*1A indicator SNP) is reliably reported on standard 23andMe arrays. *1C is less consistently genotyped; specialty pharmacogenomic panels (Sonic Genetics, Cerbo, Genomic Express) cover it more thoroughly. Promethease + raw 23andMe data interpretation can fill in some gaps.

CYP2C9 + CYP2C19 (~10% of metabolism — minor axis):

• CYP2C9*2 / *3 carriers (slow metabolizers) — modestly elevated agomelatine exposure
• Not clinically dose-modifying alone

ABCB1 (P-glycoprotein efflux transporter):

• ABCB1 polymorphisms also affect agomelatine PK per Saiz-Rodríguez 2019, though magnitude is less than CYP1A2

Practical action for Dylan after 23andMe (June 2026):

• Pull rs762551 — *1F/*1F homozygous (high-inducibility) carriers with smoking exposure or strong inducers may have low agomelatine exposure → 50 mg dose may be needed, or non-response is possible
• Pull rs2069514 if available — *1C carriers may be at elevated hepatotoxicity risk → consider lowest effective dose (25 mg) and tighter LFT monitoring
• Nordic/British ancestry: *1F frequency is high (~60% allele frequency in Caucasian populations), so most Caucasians are *1F carriers; *1C frequency is much lower

Clinical implementation status: No CPIC guideline for agomelatine + CYP1A2 yet (as of 2026). The pharmacogenomic data is suggestive but not at the formal-dosing-guidance level seen for warfarin-CYP2C9 or clopidogrel-CYP2C19.

US: Not approved. No legitimate US pharmacy stocks agomelatine. Importation is technically illegal under FDA's "unapproved drug" framework, though personal-import 90-day-supply enforcement is generally lax for non-controlled drugs.

The hard part for Dylan: prescriber + LFT monitoring, not the molecule itself. Sourcing the tablets from India is straightforward at modafinil-comparable cost. Finding a US prescriber willing to (a) acknowledge an unapproved-in-US drug and (b) order baseline + 3/6/12/24-week LFTs is the harder problem. Options:

• US telehealth psychiatrist familiar with EU-only drugs (rare; some "concierge" psych practices)
• EU/UK telehealth (Dr. Felix UK, Practio EU, etc.) — would write the Rx, leaves LFT monitoring as Dylan's problem
• Run own LFT monitoring through standalone direct-to-consumer labs (Quest, Labcorp via marketplace services like Marek Health, Function Health, Ulta Lab Tests) — feasible, ~$30-60 per LFT panel, 4 panels in first 24 weeks = ~$120-240 added cost
• Ring health platform Dylan already uses doesn't replace LFTs (different biomarker set)

Estimated all-in cost for Dylan if pursued:

• Indian pharmacy supply: ~$20-60/mo
• LFT panels x4 in first 24 weeks: ~$120-240 amortized
• One-time consult with EU/UK telehealth prescriber: ~$50-100
• Total first-year cost: ~$400-1000. Higher than V5 modafinil-class items but not prohibitive.

Baseline (before starting)

• ALT, AST, GGT, ALP, total + direct bilirubin — all four needed, not just ALT/AST. Hold initiation if ALT or AST >3× ULN.
• CBC, CMP — general baseline including renal function
• CYP1A2 genotype if 23andMe data available (rs762551 standard; rs2069514 specialty panels)
• HAM-D / PHQ-9 if depression component present
• HAM-A / GAD-7 if anxiety component present
• Pittsburgh Sleep Quality Index (PSQI) — baseline subjective sleep quality
• Sleep diary 14 days pre-start — sleep onset latency, wake times, total sleep time, mid-sleep awakenings, morning grogginess (1-10)
• Dim-light melatonin onset (DLMO) if accessible — gold standard for chronotype assessment; rarely run outside research settings
• Wearable sleep tracking baseline (Dylan has Colmi R06 ring data) — can substitute imperfectly for DLMO

During use

• LFTs at 3, 6, 12, 24 weeks per EU schedule. No exceptions. Restart clock at any dose increase.
• PHQ-9 / GAD-7 / sleep diary every 2-4 weeks first 12 weeks, then monthly
• Subjective tracking: sleep onset latency, mid-sleep awakenings, morning grogginess, mood/motivation/anhedonia, sexual function (sanity-check that the no-sexual-side-effect profile holds)
• Symptoms suggesting hepatotoxicity: dark urine, light stools, jaundice, RUQ pain, persistent fatigue, pruritus → STOP IMMEDIATELY, recheck LFTs within 48 hr
• Bedtime drift if using for chronotype migration — track weekly to see if phase advance is occurring

Post-cycle / discontinuation

• LFTs once at 4-8 weeks post-discontinuation if any were elevated during use
• Sleep diary for 4-8 weeks post-stop — assess whether circadian gain is held by behavioral anchors or regresses
• Mood tracking — agomelatine has no discontinuation syndrome but baseline mood may drift on stop