Plan B Indication:

For the treatment of menopausal and postmenopausal disorders and alone or in combination with other hormones as an oral contraceptive.

Plan B Mechanism Of Action:

Binds to the progesterone and estrogen receptors. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins like levonorgestrel will slow the frequency of release of gonadotropin releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH (luteinizing hormone) surge.

Plan B Drug Interactions:

Amobarbital Phenobarbital decreases the effect of levonorgestrel
Aprobarbital Phenobarbital decreases the effect of levonorgestrel
Butabarbital Phenobarbital decreases the effect of levonorgestrel
Butalbital Phenobarbital decreases the effect of levonorgestrel
Butethal Phenobarbital decreases the effect of levonorgestrel
Carbamazepine Carbamazepine decreases the contraceptive effect
Dihydroquinidine barbiturate Phenobarbital decreases the effect of levonorgestrel
Heptabarbital Phenobarbital decreases the effect of levonorgestrel
Hexobarbital Phenobarbital decreases the effect of levonorgestrel
Methohexital Phenobarbital decreases the effect of levonorgestrel
Methylphenobarbital Phenobarbital decreases the effect of levonorgestrel
Pentobarbital Phenobarbital decreases the effect of levonorgestrel
Phenobarbital Phenobarbital decreases the effect of levonorgestrel
Primidone Phenobarbital decreases the effect of levonorgestrel
Quinidine barbiturate Phenobarbital decreases the effect of levonorgestrel
Secobarbital Phenobarbital decreases the effect of levonorgestrel
Talbutal Phenobarbital decreases the effect of levonorgestrel
Phenytoin Phenytoin decreases the contraceptive effect
Mephenytoin Phenytoin decreases the contraceptive effect
Fosphenytoin Phenytoin decreases the contraceptive effect
Ethotoin Phenytoin decreases the contraceptive effect

Plan B Food Interactions:

Avoid alcohol.
Take with food.
Avoid excessive quantities of coffee or tea (Caffeine).
Increase dietary intake of magnesium, folate, vitamin B6, B12, and/or consider taking a multivitamin.
Take at the same time everyday.

Plan B Generic Name:

Synonyms:

  • Levonorgestrelum [Inn-Latin]

Drug Type:

Small Molecule; Approved; Investigational

Absorption:

Levonorgestrel is not subjected to a "first-pass" effect and is virtually 100% bioavailable.

Toxicity (Overdose):

LD50>5000 mg/kg (orally in rats)

Protein Binding:

55%

Biotransformation:

Hepatic

Half Life:

Not Available

Dosage Forms of Plan B:

Insert, extended release Intrauterine
Tablet Oral

Chemical IUPAC Name:

(8R,9S,10R,13S,14S,17R)-13-ethyl-17-ethynyl-17-hydroxy-1,2,6,7,8,9,10,11,12,14,15,16-dodecahydrocyclopenta[a]phenanthren-3-one

Organisms Affected:

Humans and other mammals

Plan B to general, pharmacology

General, pharmacology..
Women's Health