Aminophylline
(theophylline ethylenediamine)
Methylxanthine bronchodilator + adenosine antagonist
Nonselective PDE inhibition (↑ cAMP) + adenosine-receptor antagonism → bronchodilation, respiratory stimulation, mild inotropy/chronotropy.
Indications
- •Refractory bronchospasm/status asthmaticus (adjunct)
- •Reversal of dipyridamole/adenosine (adenosine antagonist)
- •Bradycardia in denervated heart / post-transplant
- •Neonatal apnea
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Loading | 5–6 mg/kg IV over 20–30 min, then 0.5 mg/kg/hr (narrow therapeutic index — level-guided) | — |
Pharmacokinetics
Onset minutes IV. Narrow therapeutic index (10–20 mcg/mL). Hepatic CYP1A2 (many interactions).
Hemodynamic effects
Tachycardia, arrhythmias.
Respiratory effects
Bronchodilation + central respiratory stimulation.
Side effects
- !Tachyarrhythmias, seizures (toxicity)
- !Nausea, tremor
- !Toxicity potentiated by CYP1A2 inhibitors (cipro, cimetidine)
Contraindications
- ×Tachyarrhythmias
- ×Seizure disorder (relative)
Clinical pearls
- ★Antagonizes adenosine → REVERSES dipyridamole/adenosine effects (e.g., stress-test symptoms) and stimulates the denervated transplanted heart.
- ★Narrow therapeutic index — arrhythmias + seizures with toxicity; many CYP1A2 drug interactions.
Other drugs in Others
- Dantrolene
Blocks RYR1 (ryanodine receptor) → ↓ Ca²⁺ release from sarcoplasmic reticulum → muscle relaxation. The only drug for malignant hyperthermia.
- Lipid Emulsion 20%
Theory: 'Lipid sink' sequesters lipophilic drugs (especially LAs), shifts to better Ca²⁺ handling, fatty acid metabolic support.
- Hydroxocobalamin
Vitamin B12a precursor; cyanide binds to cobalt center of hydroxocobalamin → forms cyanocobalamin (B12) → renal excretion. Also scavenges nitric oxide → vasoconstriction.
- Octreotide
Long-acting somatostatin analogue → suppresses splanchnic blood flow, GI/pancreatic secretions, GH, glucagon, insulin, and serotonin/vasoactive-peptide release.
- Alvimopan
Blocks GI mu-opioid receptors WITHOUT crossing the blood-brain barrier → reverses opioid-induced gut slowing while preserving central analgesia. Accelerates return of bowel function.
- Phentolamine
Competitive, reversible α1 + α2 blockade → vasodilation. Short-acting.
- Inhaled Nitric Oxide
Inhaled NO diffuses to pulmonary vascular smooth muscle → ↑ cGMP → SELECTIVE pulmonary vasodilation only in VENTILATED lung units (improves V/Q matching). Inactivated by hemoglobin before reaching systemic circulation → no systemic hypotension.
- Digoxin Immune Fab
Ovine Fab fragments bind free digoxin → the complex is renally excreted → rapidly reverses digoxin/digitoxin toxicity.
Browse all classes: /reference/drugs
Suggested reading
- •Miller's Anesthesia, 9e
- •FDA package insert
