Tocolytics, Calcium Channel Blockers: Magnesium Sulfate (mgso4), Ritodrine, Verapamil, Terbutaline, Nifedipine, Oxytocin Antagonists, Atociban mnemonic

Tocolytics

Group of drugs given to delay onset of labor (usually in premature rupture of membranes, or preterm onset of contractions), acting via various mechanisms
Magnesium Sulfate (MgSO4) [Magnet with sulfur (yellow) poles]
- First line of therapy
- Acts as a calcium antagonist and membrane stabilizer, thus decreasing the force of contractions
- Used prophylactically in patients with preeclampsia to prevent seizures continued for 12-24 hrs after delivery
- Side effects include fatigue, headaches, diplopia and flushing
- Toxicity is associated with hypoxia, respiratory depression and cardiac arrest
Ritodrine [Riddle (question mark) drain]
- Beta 2 receptor agonist [clover with beta 2 activity]
- Acts on smooth muscle cells to increase levels of cAMP (via adenylate cyclase), which decreases levels of free calcium ions and reduces contractions
- Side effects include tachycardia, headaches, and anxiety
  - Verapamil is commonly used to alleviate the side effects of tachycardia
Terbutaline [tertiary-boot-line tying off the cervix to prevent labor, or terrier-but-alien tugging at line]
- Beta 2 receptor agonist, long acting, same mechanism of action as ritodrine
Calcium channel blockers [Cal, the California surfer's board is blocking the cervical canal, and stopping contractions]
- Calcium is blocked from entering the smooth muscle cells, thus preventing contractions
- Nifedipine and Verapamil commonly used
- Dizziness, flushing and headaches are among side effects
Oxytocin antagonists [Oxy(O2)-2-sin, blocked]
- Oxytocin is a hormone that stimulates the uterus to contract
- Drugs such as Atociban have been shown to reduce contractions

Visual Mnemonic - Tocolytics, Calcium Channel Blockers: Magnesium Sulfate (mgso4), Ritodrine, Verapamil, Terbutaline, Nifedipine, Oxytocin Antagonists, Atociban
Copyright 2004-2005 Julia Biernot, all rights reserved.