Tuesday, October 11, 2016

Carbamazepine for Trigeminal Neuralgia

  • Trigeminal neuralgia (TN), also known as tic douloureux, is a distinctive facial pain syndrome that may become recurrent and chronic. 
  • It is characterized by unilateral pain following the sensory distribution of cranial nerve V (typically radiating to the maxillary or mandibular area in 35% of affected patients) and is often accompanied by a brief facial spasm or tic.1
Carbamazepine
  • The only approved medication by FDA for the treatment of Trigeminal Neuralgia 
  • Pharmacologic therapy is the initial treatment of most patients with classic TN (ie, TN that is idiopathic or caused by neurovascular compression). 
  • Surgery is reserved for patients who are refractory to medical therapy.
  • Carbamazepine is the best studied treatment for classic TN and is established as effective. 
  • Side effects can be a problem but are generally manageable, particularly if low doses are prescribed initially with gradual titration.2
Dosing
Ref: Clinical Pharmacokinetics Pharmacy Handbook,2015

Ref: https://www.drugs.com/dosage/carbamazepine.html


Therapeutic Drug Monitoring(TDM)

  • Sampling time: 30 minutes before the next dose.
 Ref: Clinical Pharmacokinetics Protocol. PSD, Sabah State Health Department. 

Ref: Clinical Pharmacokinetics Pharmacy Handbook, 2015

Toxic level
  • Lexicomp: >15mcg/ml
  • Medscape: The toxic concentration/critical laboratory value is greater than 30-40 mg/L

Ref: Clinical Pharmacokinetics Pharmacy Handbook, 2015
References

  1. http://emedicine.medscape.com/article/1145144-overview
  2. www.uptodate.com
  3. Clinical Pharmacokinetics Pharmacy Handbook, 2015
  4. https://www.drugs.com/dosage/carbamazepine.html

Friday, October 7, 2016

Interactions: Kalimate

Dietary
  • Mix the sodium polystyrene sulfonate powder with water, or with honey or jam to make it taste better.
  • Avoid inhaling the oral powder while you are preparing a dose.
  • Do not mix the powder with any juice or other liquid that contains potassium, such as orange juice.
  • The potassium in foods will bind with the resin preventing adequate potassium removal from patients with hyperkalemia.
Supplementation
  • Sodium polystyrene sulfonate can bind to calcium, iron, magnesium, and other minerals in the gastrointestinal tract.
  • This may inactivate both sodium polystyrene sulfonate and the mineral it binds to and reduce the effectiveness of both medications.
  • To avoid or minimize the interaction, the dosing times of sodium polystyrene sulfonate and multivitamin with minerals should be separated by several hours
Antacids & Laxatives
  • alkalosis following concurrent administration of cation-exchange resins and non-absorbable cation-donating antacids and laxatives such as magnesium hydroxide and aluminium carbonate.
  • Intestinal obstruction due to concretions of aluminium hydroxide has been reported when aluminium hydroxide has been combined with the resin (sodium form).
  • Management: Monitor for signs/symptoms of intestinal obstruction with concomitant use of calcium polystyrene sulfonate and aluminum hydroxide.
  • Adequate fluid intake, laxative use, alternative antacid agents, and/or limiting duration of therapy may help reduce risks
Sorbitol
  • Concomitant use of Sorbitol with calcium polystyrene sulfonate is not recommended due to cases of intestinal necrosis and other serious gastrointestinal adverse reactions, which may be fatal
References:
  1. Resonium Information Leaflet
  2. https://www.drugs.com/food-interactions/sodium-polystyrene-sulfonate.html?professional=1
  3. https://www.medicines.org.uk/emc/medicine/6739