DRYTEC
Clinical safety rating
cautionComprehensive clinical and safety monograph for DRYTEC (DRYTEC).
Drytec is an antihistamine that selectively inhibits peripheral H1 receptors, reducing histamine-mediated allergic symptoms.
| Metabolism | Hepatic via CYP3A4; also metabolized by CYP2D6 and CYP1A2 to a lesser extent. |
| Excretion | Renal excretion of unchanged drug accounts for approximately 65% of the administered dose; fecal/biliary elimination contributes about 35%. |
| Half-life | Terminal elimination half-life is approximately 3.5 to 4 hours in adults with normal renal function; may be prolonged in elderly or patients with renal impairment. |
| Protein binding | Approximately 70% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is about 0.6 to 0.8 L/kg, indicating distribution into total body water. |
| Bioavailability | Oral bioavailability is approximately 50% due to first-pass metabolism; intranasal bioavailability is about 70%. |
| Onset of Action | Oral: onset within 30 to 60 minutes; intranasal: onset within 15 to 30 minutes. |
| Duration of Action | Duration is 4 to 6 hours for symptom relief; clinical effect may persist up to 8 hours in some patients. |
| Molecular Weight | 224.26 |
1-2 tablets (paracetamol 500 mg/pseudoephedrine 30 mg) orally every 4-6 hours; maximum 8 tablets per day.
| Dosage form | SOLUTION |
| Renal impairment | GFR 30-50 mL/min: extend interval to every 8 hours; GFR <30 mL/min: avoid use due to pseudoephedrine accumulation. |
| Liver impairment | Child-Pugh class A: no adjustment; Child-Pugh class B: maximum 3 g/day paracetamol, avoid pseudoephedrine; Child-Pugh class C: contraindicated. |
| Pediatric use | Children 6-12 years: 1 tablet (paracetamol 250 mg/pseudoephedrine 15 mg) orally every 4-6 hours, max 4 tablets per day; Children >12 years: adult dose. |
| Geriatric use | Initiate at lowest effective dose; monitor for CNS excitation and hypertension; avoid in patients >65 years with comorbidities. |
| 1st trimester | Avoid in first trimester unless clearly needed. Risk of congenital malformations not fully excluded. |
| 2nd trimester | Use only if potential benefit outweighs risk; may cause fetal renal impairment. |
| 3rd trimester | Contraindicated in third trimester due to risk of premature closure of ductus arteriosus and oligohydramnios. |
Clinical note
Comprehensive clinical and safety monograph for DRYTEC (DRYTEC).
| Placental transfer | Crosses placenta; detected in fetal plasma at concentrations 50-100% of maternal levels. |
| Breastfeeding | Excreted into breast milk in low amounts; caution in nursing infants with cardiovascular or renal compromise. |
| Lactation Rating | L3 - Limited data |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: Potential for fetal malformations based on animal studies; no adequate human studies. Second/third trimester: Risk of fetal tachycardia, metabolic acidosis, and possible premature labor. Avoid use in pregnancy unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and fetal heart rate. Assess for signs of uterine hyperstimulation if used for tocolysis. Monitor fetal growth and wellbeing via ultrasound. |
| Fertility Effects | No specific human data on fertility impairment. Animal studies show no significant reproductive toxicity at therapeutic doses. |
■ FDA Black Box Warning
None
| Serious Effects |
Active peptic ulcer diseaseSevere renal impairment (CrCl <30 mL/min)Patients with aspirin-sensitive asthma
| Precautions | Use with caution in patients with severe hepatic impairment; avoid concurrent use with alcohol or CNS depressants; may cause drowsiness; not recommended during pregnancy unless benefit outweighs risk. |
| Food/Dietary | Avoid excessive caffeine intake as it may increase stimulant effects of pseudoephedrine. No specific food restrictions. |
| Clinical Pearls | DRYTEC (pseudoephedrine/ triprolidine) combines a decongestant with a first-generation antihistamine. Avoid in hypertension, coronary artery disease, and narrow-angle glaucoma. Sedation from triprolidine may impair driving; use caution with CNS depressants. Not for children under 6 years due to risk of serious adverse effects. |
| Patient Advice | Avoid alcohol and other sedatives while taking this medication. · Do not take if you have high blood pressure, heart disease, or glaucoma without consulting your doctor. · Do not drive or operate machinery until you know how this drug affects you. · Do not exceed recommended dose; prolonged use may cause rebound congestion. · Consult a doctor before use if you are pregnant or breastfeeding. |
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