Doxycycline
Severe
Textbook-cited
Lithium toxicity
Avoid tetracycline or monitor lithium levels and reduce dose
Source: KDT 7e · p949
Drug reference
Lithium
Mood stabilizer (monovalent cation) · Antipsychotic
Also known as Lithium Carbonate, Lithium Citrate
START
Baseline: eGFR/creatinine, TSH, calcium, ECG, pregnancy test. Counsel on consistent sodium intake and hydration. Lithium levels at 5-7 days after start or dose change (12-hour post-dose trough).
TYPICAL MAX
Serum lithium 0.8-1.2 mEq/L (acute); 0.6-0.8 mEq/L (maintenance); >1.5 mEq/L = toxic. Levels >2.0 mEq/L require urgent intervention (hemodialysis if symptomatic or >2.5).
STOP IF
Lithium level >1.5 mEq/L with symptoms, severe dehydration, acute kidney injury, uncontrolled arrhythmia, severe hypothyroidism.
WATCH
Serum lithium every 3-6 months (stable), more frequently if ill, dehydrated, or on interacting drugs. Renal function (eGFR, urinalysis) every 6 months. TSH every 6-12 months. Calcium annually. Any condition causing sodium loss (vomiting, diarrhea, diuretics) increases toxicity risk. NSAIDs and ACE inhibitors raise lithium levels.
CDSCO approvedSchedule HATC N05AN01
KDIGO 2024 + manufacturer label
- ONSET
- 30min · Onset ~30 min
- PEAK
- 2h · Tmax IR 0.5-2h; ER 4-5h
- t½
- 1d · t½ 18-24h (young); 30-36h (elderly)
- DURATION
- 12h · 12 hours (BID)
EXCRETION
Renal unchanged (~95%)
route + CYP
INTERACTIONS
12 major
SEVERE in our sources
PREGNANCY
First trimester: risk of Ebstein's anomaly (cardiac malformation) and other congenital defects. If continued, use lowest effective dose, divide doses, and monitor levels frequently. Lithium levels fall during pregnancy—increase dose and monitor. Postpartum: levels rise rapidly—reduce dose.
FDA category + note
Top interactionssee all 12 →
- DoxycyclineSevereTextbook-citedKDT 7e · p949
- FurosemideSevereTextbook-citedKDT 7e · p949
- HydrochlorothiazideSevereTextbook-citedKDT 7e · p949
- MinocyclineSevereTextbook-citedKDT 7e · p949
Available in India
113 branded formulations. Look up specific brands in the Drugs workspace.
Mechanism
Exact mechanism unknown. Modulates glutamate neurotransmission, inhibits glycogen synthase kinase-3 (GSK-3), modulates inositol monophosphatase, and affects cAMP signaling. Stabilizes mood by normalizing neurotransmitter function in limbic system.
Indications
Bipolar disorder (acute mania and maintenance prophylaxis)Bipolar depression (adjunctive or monotherapy)Recurrent unipolar depression (augmentation)Schizoaffective disorderCluster headache prophylaxis (off-label)
Dosing
- Adult
- Acute mania: 600mg PO TID or 900mg ER BID initially; titrate to serum lithium 0.8-1.2 mEq/L. Maintenance: 300mg PO TID-TID or 450mg ER BID; target 0.6-0.8 mEq/L (elderly: 0.4-0.6 mEq/L). Depression augmentation: 300mg daily, titrate to 0.4-0.8 mEq/L.
- Pediatric
- ≥7 years: 15-20mg/kg/day in 2-3 divided doses; titrate to serum level 0.8-1.2 mEq/L.
- Renal adjustment
- CrCl ≥30 mL/min: use with caution — reduce dose and monitor serum lithium levels closely (narrow therapeutic index). CrCl <30 mL/min: avoid — per FDA labeling, lithium should not be used in severe renal insufficiency (creatinine clearance <30 mL/min by Cockcroft-Gault).
- Hepatic adjustment
- No adjustment needed (renally eliminated).
- Geriatric
- Start 150-300mg daily; target 0.4-0.6 mEq/L; increased risk of toxicity due to reduced GFR.
- Max dose
- No fixed max—serum level guided (max therapeutic 1.2 mEq/L; toxic >1.5 mEq/L)
Pharmacokinetics
Onset
Acute mania: 5-7 days; maintenance: 1-2 weeks for full mood stabilization
Peak effect
Tmax: immediate-release 0.5-2 hours; ER 4-5 hours; steady-state in ~5 days
Duration
8-12 hours per dose (BID-TID dosing)
Half-life
~18-24 hours (young adults); ~30-36 hours (elderly); ~48 hours in renal impairment
Bioavailability
~95-100%
Protein binding
Not protein bound (0%)
Metabolism
Not metabolized (eliminated unchanged)
Excretion
~95% unchanged in urine via glomerular filtration and proximal tubular reabsorption (competes with sodium)
Contraindications
- Severe renal impairment (CrCl <10 mL/min)
- Severe cardiovascular disease (sick sinus syndrome, AV block)
- Dehydration or sodium depletion
- Addison's disease
- Untreated hypothyroidism
- Pregnancy (first trimester—teratogenic)
Side effects
Common
Tremor (fine, bilateral hands)Polydipsia and polyuria (nephrogenic diabetes insipidus)Weight gainNausea and diarrheaHypothyroidismCognitive dullingAcne / psoriasis exacerbation
Serious
- Lithium toxicity (coarse tremor, confusion, ataxia, seizures, coma—can be fatal)
- Nephrogenic diabetes insipidus
- Chronic interstitial nephritis
- Hypothyroidism
- Hyperparathyroidism / hypercalcemia
- Sinus node dysfunction / bradycardia
- Ebstein's anomaly (first-trimester exposure)
Pregnancy & lactation
Pregnancy
First trimester: risk of Ebstein's anomaly (cardiac malformation) and other congenital defects. If continued, use lowest effective dose, divide doses, and monitor levels frequently. Lithium levels fall during pregnancy—increase dose and monitor. Postpartum: levels rise rapidly—reduce dose.
Lactation
Excreted in breast milk at 30-50% of maternal serum level; infant serum levels ~10-50% of maternal. Monitor infant for tremor, lethargy, cyanosis, TSH. Use lowest effective maternal dose; consider formula feeding if infant shows toxicity signs.
Drug interactions
Furosemide
Severe
Textbook-cited
Lithium toxicity.
Reduce lithium dose and monitor serum levels
Source: KDT 7e · p949
Hydrochlorothiazide
Severe
Textbook-cited
Lithium toxicity.
Reduce lithium dose and monitor serum levels
Source: KDT 7e · p949
Minocycline
Severe
Textbook-cited
Lithium toxicity
Avoid tetracycline or monitor lithium levels and reduce dose
Source: KDT 7e · p949
Spironolactone
Severe
Textbook-cited
Lithium toxicity.
Reduce lithium dose and monitor serum levels
Source: KDT 7e · p949
Tetracycline
Severe
Textbook-cited
Lithium toxicity
Avoid tetracycline or monitor lithium levels and reduce dose
Source: KDT 7e · p949
Bendroflumethiazide
Severe
Textbook
Increased lithium levels and risk of toxicity.
Must be avoided.
Source: G&G 14e · p378
Hydroflumethiazide
Severe
Textbook
Increased lithium levels and risk of toxicity.
Must be avoided.
Source: G&G 14e · p378
Metolazone
Severe
Textbook
Increased lithium levels and risk of toxicity.
Must be avoided.
Source: G&G 14e · p378
Pancuronium
Severe
Textbook
Prolonged paralysis.
Not explicitly stated
Source: KDT 7e
Succinylcholine
Severe
Textbook
Prolonged paralysis.
Not explicitly stated
Source: KDT 7e
Sulfonylureas
Severe
Textbook
Enhanced sulfonylurea action, potentially precipitating severe hypoglycaemia.
Monitor blood glucose closely and adjust sulfonylurea dosage as necessary.
Source: KDT 7e · p271
Related guidelines
Ask House about Lithium
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, Katzung, BNF·Verified: 2026-06-01 · House clinical team·Cockpit curated: 2026-05-19