Diphenhydramine: Difference between revisions
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==General== | ==General== | ||
*Type: [[Antihistamines]] | *Type: [[Antihistamines]] / H1 blocker | ||
*Dosage Forms: | *Dosage Forms: Oral, IM, IV | ||
*Common Trade Names: | *Common Trade Names: Benadryl | ||
==Adult Dosing== | ==Adult Dosing== | ||
*25-50 mg | *[[Allergic reaction]] | ||
**Oral: 25-50mg q4-8h, max 300mg/day | |||
**IM/IV: 10-50mg/dose | |||
*Parkinsonian symptoms | |||
**Oral: 25-50mg tid-QID | |||
**IM/IV: 10-50mg/dose | |||
*[[Insomnia]]: 50mg PO qhs | |||
*Injectable 1% diphenhydramine (10 mg/mL) can be used as a local anesthestic alternative to ester/amide anesthetics<ref>Pavlidakey PG et al. Diphenhydramine as an Alternative Local Anesthetic Agent. J Clin Aesthet Dermatol. 2009 Oct; 2(10): 37–40.</ref> | |||
**Sodium channel blocker mechanism | |||
**1-2 mL of 1% diphenhydramine at a time, to not exceed excessive sedation dose | |||
**Typical vial is 50 mg/mL, so to make 10 mg/mL: | |||
***10 mL NS removed from 50 mL vial | |||
***Add 10 mL of 50 mg/mL diphenhydramine to 40 mL of NS | |||
***Sedation is dose related and is similar to what would be expected for IM doses | |||
***Relative contraindications are the same for IM diphenhydramine administration | |||
==Pediatric Dosing== | ==Pediatric Dosing== | ||
*[[Allergic reaction]] | |||
**Oral/IM/IV: 5mg/kg/day divided q6-8h (1.25-1.67mg/kg/dose) | |||
**Alternate PO dosing | |||
***2-6 yo: 6.25mg q4-6h | |||
***6-12 yo: 12-25mg q4-6h | |||
***>12 yo: Adult dosing | |||
==Special Populations== | ==Special Populations== | ||
*[[Drug | *[[Drug pregnancy categories|Pregnancy Rating]]: B | ||
*Lactation: | *Lactation Risk: Enters breast milk | ||
*Renal Dosing | *Renal Dosing: n/a | ||
*Hepatic Dosing: n/a | |||
*Hepatic Dosing | |||
==Contraindications== | ==Contraindications== | ||
| Line 24: | Line 40: | ||
==Adverse Reactions== | ==Adverse Reactions== | ||
===Serious=== | ===Serious=== | ||
*[[Anticholinergic toxicity]] | |||
*CNS depression | |||
*Cardiac arrthymias (Sodium channel blockade) | |||
*[[Seizures]] | |||
===Common=== | ===Common=== | ||
*Sedation | |||
===Overdose related=== | |||
*[[Opsoclonus]] - conjugate irregular and nonrhythmical jerking movements of the eyes was reported in a 20-year-old woman who had ingested 5 grams<ref>NEJM. http://www.nejm.org/action/showMediaPlayer?doi=10.1056%2FNEJMicm1002035&aid=NEJMicm1002035_attach_1&area=&</ref> | |||
==Pharmacology== | ==Pharmacology== | ||
*Half-life: | *Half-life: Children 5 hours, Adults 9 hours, Elderly 13.5 hours | ||
*Metabolism: | *Metabolism: Hepatic | ||
*Excretion: | *Excretion: Urine | ||
*Mechanism of Action: | *Mechanism of Action: [[Antihistamines]] / H1 blocker | ||
==See Also== | ==See Also== | ||
*[[Antihistamines]] | |||
*[[Anticholinergic toxicity]] | |||
== | ==References== | ||
<references/> | |||
[[Category:Pharmacology]] | |||
[[Category: | |||
Latest revision as of 22:29, 7 March 2021
General
- Type: Antihistamines / H1 blocker
- Dosage Forms: Oral, IM, IV
- Common Trade Names: Benadryl
Adult Dosing
- Allergic reaction
- Oral: 25-50mg q4-8h, max 300mg/day
- IM/IV: 10-50mg/dose
- Parkinsonian symptoms
- Oral: 25-50mg tid-QID
- IM/IV: 10-50mg/dose
- Insomnia: 50mg PO qhs
- Injectable 1% diphenhydramine (10 mg/mL) can be used as a local anesthestic alternative to ester/amide anesthetics[1]
- Sodium channel blocker mechanism
- 1-2 mL of 1% diphenhydramine at a time, to not exceed excessive sedation dose
- Typical vial is 50 mg/mL, so to make 10 mg/mL:
- 10 mL NS removed from 50 mL vial
- Add 10 mL of 50 mg/mL diphenhydramine to 40 mL of NS
- Sedation is dose related and is similar to what would be expected for IM doses
- Relative contraindications are the same for IM diphenhydramine administration
Pediatric Dosing
- Allergic reaction
- Oral/IM/IV: 5mg/kg/day divided q6-8h (1.25-1.67mg/kg/dose)
- Alternate PO dosing
- 2-6 yo: 6.25mg q4-6h
- 6-12 yo: 12-25mg q4-6h
- >12 yo: Adult dosing
Special Populations
- Pregnancy Rating: B
- Lactation Risk: Enters breast milk
- Renal Dosing: n/a
- Hepatic Dosing: n/a
Contraindications
- Allergy to class/drug
Adverse Reactions
Serious
- Anticholinergic toxicity
- CNS depression
- Cardiac arrthymias (Sodium channel blockade)
- Seizures
Common
- Sedation
- Opsoclonus - conjugate irregular and nonrhythmical jerking movements of the eyes was reported in a 20-year-old woman who had ingested 5 grams[2]
Pharmacology
- Half-life: Children 5 hours, Adults 9 hours, Elderly 13.5 hours
- Metabolism: Hepatic
- Excretion: Urine
- Mechanism of Action: Antihistamines / H1 blocker
See Also
References
- ↑ Pavlidakey PG et al. Diphenhydramine as an Alternative Local Anesthetic Agent. J Clin Aesthet Dermatol. 2009 Oct; 2(10): 37–40.
- ↑ NEJM. http://www.nejm.org/action/showMediaPlayer?doi=10.1056%2FNEJMicm1002035&aid=NEJMicm1002035_attach_1&area=&