📖 Pharmacology
Mefenamic acid
PharmacologyMefenamic acid
Analgesic, anti‐inflammatory properties less effective than aspirin
Short half‐lives, should not be used for longer than one week and never in pregnancy and in children.
Enhances oral anticoagulants
Used to treat pain, including menstrual pain. It decreases inflammation (swelling) and uterine contractions.
Lamotrigine
PharmacologyLamotrigine (Lamictal): newer; broad spectrum (for most seizure types)
Mechanism: ↓ reactivation of Na channels (↑ refractory period, blocks high frequency cell firing)
Side effects: dizziness, ataxia, fatigue, nausea, no significant drug interactions
Sympathomimetics
PharmacologySympathomimetics
Beta-Adrenergic Agonists
Beta1-adrenergic agonists (dopamine, dobutamine, prenalterol, xamoterol) have been used to treat acute and chronic heart failure, but have limited usefulness in chronic CHF because of their arrhythmogenic effects, short duration of action, the development of tolerance, and necessity of parenteral administration
Dopamine (i.v.) is used in acute heart failure (cardiogenic shock) to increase blood pressure and increase cardiac output
- It has a short half-life (1 min)
- At high doses dopamine has potent peripheral vasoconstrictor effects (alpha-receptor stimulation), in addition to its inotropic effects
- Low dose dopamine has a renal artery dilating effect and may improve sodium and water excretion in patients refractory to loop diuretics
- When systolic pressure is greater than 90 mm Hg, nitroprusside can be added to reduce ventricular filling pressure and reduce afterload
- i.v. furosemide should also be administered to reduce edema
Levodopa and ibopamine, analogs of dopamine that can be administered orally, have been shown to improve symptoms in some patients, but can exhibit arrhythmogenic side-effects and tachyphylaxis
Dobutamine is a somewhat selective beta1-adrenergic agonist that lacks vasoconstrictor activity and causes minimal changes in heart rate
- It is frequently added to nitroprusside when blood pressure is adequate to increase cardiac output
- It is administered as an i.v. infusion to treat acute severe heart failure
- It has a short half-life (2.4 min) and is only used on a short-term basis, although long-term beneficial effects on cardiac function have been noted
- After 72 hours of therapy, tolerance can develop to dobutamine necessitating switch to other inotropic support (e.g. milrinone)
- Dobutamine can enhance AV conduction and worsen atrial tachycardia
Prenalterol and xamoterol are partial beta1-adrenergic agonists that may simultaneously stimulate beta1-receptors and block the receptors from stimulation by endogenous catecholamines, thereby protecting against beta1-receptor down-regulation
Ketorolac
PharmacologyKetorolac
Mechanism of action
primary action responsible for its anti-inflammatory/antipyretic/analgesic effects is inhibition of prostaglandin synthesis through inhibition of the enzyme cyclooxygenase (COX). Ketorolac is not a selective inhibitor of COX enzymes
Indications: short-term management of pain
Contraindications
hypersensitivity to ketorolac, and against patients with the complete or partial syndrome of nasal polyps, angioedema, bronchospastic reactivity or other allergic manifestations to aspirin or other non-steroidal anti-inflammatory drugs (due to possibility of severe anaphylaxis).