Available Tools

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💊 Drug Interaction Checker

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📊 Titration Guide

Step-by-step titration schedules cross-referenced against FDA prescribing information and current clinical guidelines.

Lamotrigine (Lamictal) Titration

Indication referenced: Bipolar I maintenance. Not FDA-approved for acute bipolar depression monotherapy; used off-label.

Standard Adult Schedule (no interacting AEDs)

Week	Dose
Weeks 1–2	25 mg PO daily
Weeks 3–4	50 mg PO daily
Week 5	100 mg PO daily
Week 6	200 mg PO daily (target maintenance dose)

With Valproate (VPA inhibits glucuronidation — half dose)

Week	Dose
Weeks 1–2	25 mg PO every other day
Weeks 3–4	25 mg PO daily
Week 5	50 mg PO daily
Week 6	100 mg PO daily (target maintenance dose)

With Enzyme Inducers without VPA (CBZ, phenytoin, phenobarbital, primidone, rifampin) — double dose

Week	Dose
Weeks 1–2	50 mg PO daily
Weeks 3–4	100 mg PO daily (divided doses)
Week 5	200 mg PO daily (divided doses)
Week 6	300 mg PO daily (divided doses)
Week 7	400 mg PO daily (divided doses) (target maintenance dose)

Missed Doses / Restart Rules

If lamotrigine is discontinued for more than 5 half-lives (approximately 5 days at steady state in a typical adult on monotherapy), the full initial titration must be restarted from Week 1 to avoid serious rash risk.

Key Counseling / Hold Criteria

• Counsel patient: call immediately for any rash, especially in the first 8 weeks.
• Hold lamotrigine for: rash with mucosal involvement, fever, lymphadenopathy, facial swelling, eosinophilia, or systemic symptoms (possible DRESS).
• A benign, non-serious rash may still require discontinuation — err on the side of caution.
• Hormonal contraceptives (estrogen-containing) and pregnancy can reduce lamotrigine levels ~50% — dose adjustment and therapeutic drug monitoring may be needed.

Sources: Lamotrigine FDA prescribing information (current revision, GlaxoSmithKline). Stahl SM. Prescriber's Guide, 7th ed. Cambridge University Press. Maudsley Prescribing Guidelines in Psychiatry, 14th ed. American Psychiatric Association Practice Guideline for the Treatment of Patients with Bipolar Disorder.

Lithium Carbonate Titration

Indications referenced: Bipolar I (acute mania, maintenance). Narrow therapeutic index.

Pre-Treatment Workup (Baseline)

• SCr / eGFR, BUN, electrolytes
• TSH, free T4
• Calcium (lithium can cause hyperparathyroidism)
• CBC
• Urine pregnancy test (Ebstein's anomaly risk — counsel)
• ECG if age ≥40 or cardiac history
• Weight / BMI baseline

Starting Dose

• Typical adult starting dose: 300 mg PO BID or TID (600–900 mg/day total).
• Elderly or impaired renal function: Start 150 mg BID (300 mg/day) and titrate more slowly.
• Preferred formulation: immediate-release for initiation; extended-release (Lithobid) can reduce GI side effects and peak-related tremor.

Target Serum Levels (12 hours post-dose, trough)

Indication	Target Level (mEq/L)
Acute mania	1.0 – 1.2 mEq/L
Maintenance	0.6 – 1.0 mEq/L
Elderly	0.4 – 0.8 mEq/L (lower end)
Toxicity concern	≥1.5 mEq/L (mild) · ≥2.0 (moderate) · ≥2.5 (severe — medical emergency)

Monitoring Schedule

Parameter	Frequency
Lithium level	Check 5 days after each dose change (steady state), then every 3 months once stable, then every 6–12 months if stable long-term
SCr / eGFR	Every 3 months for first year, then every 6–12 months
TSH	Every 6 months
Calcium	Annually
Weight, BMI	Every visit

Level Timing Rule

Lithium levels must be drawn as a 12-hour trough (exactly 12 hours after the last dose, typically morning draw if patient takes evening dose). Levels drawn at other times are not interpretable for dose adjustment.

Key Drug Interactions

• NSAIDs (except aspirin, sulindac): can raise lithium levels significantly.
• Thiazide diuretics: decrease renal clearance, can raise levels.
• ACE inhibitors / ARBs: can raise levels.
• Dehydration / low-sodium diet: raises levels.
• Caffeine withdrawal: can raise levels (caffeine is mildly diuretic).

Sources: Lithium carbonate FDA prescribing information. Stahl SM. Prescriber's Guide, 7th ed. American Psychiatric Association Practice Guideline for the Treatment of Patients with Bipolar Disorder. Maudsley Prescribing Guidelines in Psychiatry, 14th ed. NICE Guideline CG185 (Bipolar Disorder).

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🔄 Switching & Withdrawal Protocols

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