Details About Overdose or Poisoning Generic Salt :: Antivenom, Latrodectus Mactans, Black Widow Spider
Antivenom, Latrodectus Mactans (Black Widow Spider)
Drug Pharmacology ::
I. Pharmacology. To produce the antivenom, horses are hyperimmunized with Latrodectus mactans(black widow spider) venom. The lyophilized protein product from pooledequine sera contains antibodies specific to certain venom fractions aswell as residual serum proteins such as albumin and globulins. Afterintravenous administration, the antivenom distributes widely throughoutthe body, where it binds to venom.
Drug Indications ::
Blackwidow envenomation–induced severe hypertension or muscle cramping thatis not alleviated by muscle relaxants, analgesics, or sedation;consider particularly in patients at the extremes of age (ie, youngerthan 1 year or older than 65 years).
Black widow envenomation in pregnancy may cause abdominal muscle spasms severe enough to threaten spontaneous abortion or early onset of labor.
Drug Contra-Indications ::
III. Contraindications. Known hypersensitivity to horse serum.
Drug Adverse Effects ::
IV. Adverse effects
Immediate hypersensitivity may occur rarely, including life-threatening anaphylaxis.
Delayed-onset serum sickness may occur after 10–14 days but is rare owing to the small volume of antivenom used in most cases.
Use in pregnancy. FDAcategory C (indeterminate). There are no data on teratogenicity. Ananaphylactic reaction resulting in shock or hypoxemia in the mothercould conceivably affect the fetus adversely (see Table III–1).
Drug Lab Interactions ::
Drug or laboratory interactions. No known interactions.
Drug Dose Management ::
Dosage and method of administration. Generally,one vial of antivenom is sufficient to treat black widow envenomationin adults or children. The antivenom is dosed on the basis of symptoms,not on patient weight.
Treat all patients in an emergency department or intensive care setting.
Before a skin test or antivenom administration, insert at least one and preferably two secure intravenous lines.
Performa skin test for horse serum sensitivity by using a 1:10 dilution ofantivenom (some experts prefer this method) or the sample of horseserum provided in the antivenom kit (according to packageinstructions). Do not perform the skin test unless signsof envenomation are present and imminent antivenom therapy isanticipated. If the skin test is positive, reconsider the need forantivenom as opposed to supportive care but do not abandon antivenomtherapy if it is needed. Even if the skin test is negative, anaphylaxismay occur unpredictably.
Ifantivenom is used in a patient with horse serum sensitivity, pretreatwith intravenous diphenhydramine (see Diphenhydramine) and cimetidine(or another H2 blocker; see Cimetidine and Other H2Blockers), and have ready at the bedside a preloaded syringe containingepinephrine (1:10,000 for intravenous use) in case of anaphylaxis.Dilute the antivenom (1:10 to 1:1000) and administer it very slowly inthese cases.
E. Reconstitutethe lyophilized product to 2.5 mL with the supplied diluent, usinggentle swirling for 15–30 minutes to avoid shaking and destroying theimmunoglobulins (as indicated by the formation of foam).
F. Dilute this solution to a total volume of 10–50 mL with normal saline.
G. Administer the diluted antivenom slowly over 15–30 minutes. One or two vials are sufficient in most cases.
Drug Chemical Formulations ::
Lyophilized antivenom (L mactans), 6000 units, contains 1:10,000 thimerosal as a preservative. Note product also listed as antivenin (Latrodectus mactans).
The suggested minimum stocking level to treat a 70-kg adult for the first 24 hours is one vial.