Hydralazine

Oral hydralazine hydrochloride is labeled for essential hypertension alone or as an adjunct. The selected injection is labeled for severe essential hypertension when oral administration is not possible or urgent blood-pressure reduction is needed. Hospital treatment requires frequent reassessment; these indications do not establish a universal hypertensive-emergency or obstetric protocol.

The AHA/ACC/HFSA guideline recommends hydralazine with isosorbide dinitrate for self-identified African American patients with NYHA III–IV HFrEF receiving optimal medical therapy. The combination may also be considered in symptomatic HFrEF when first-line ARNI/ACE inhibitor/ARB therapy cannot be used because of intolerance or renal insufficiency. This combination indication and regimen must not be inferred from the single-ingredient hypertension label; fixed-dose BiDil and nitrate dosing are outside this product-specific reference.

Start 10 mg four times daily for 2–4 days, then 25 mg four times daily for the remainder of week 1; from week 2, the label increases to 50 mg four times daily. Adjust maintenance to the lowest effective dose. Selected resistant patients may require up to 300 mg/day, but the label emphasizes increased toxic reactions at large doses and considers lower-dose combination therapy. This is a legacy labeled schedule, not a mandatory escalation for every patient.

The selected label uses 20–40 mg IM or as a direct rapid IV bolus, repeated as necessary when oral treatment cannot be given. It does not supply a universal repeat interval. Marked renal impairment may require a lower dose. Check blood pressure frequently: maximal decline averages 10–80 minutes, so avoid assuming an immediate final response. Transition to oral therapy when appropriate, often within 24–48 hours. Follow the institution’s indication-specific protocol; this label regimen is not a home-use instruction.

Controlled pediatric safety/effectiveness are not established, although the labels describe clinical experience. Oral: start 0.75 mg/kg/day in four divided doses and increase over 3–4 weeks to no more than 7.5 mg/kg/day or 200 mg/day, whichever is lower. The injection label describes 1.7–3.5 mg/kg/day in four to six divided IM/IV doses. Pediatric use requires specialist selection of an appropriate formulation and monitoring; no universal emergency bolus or age cutoff is invented.

Food increases oral hydralazine plasma levels; keep administration consistent with the prescribed directions and monitor response. The injection must be used immediately after opening and must not be added to infusion solutions; inspect for particles or discoloration and discard unused drug. Labels advise caution with advanced renal damage but supply no standardized eGFR or hepatic adjustment table.

Both selected labels contraindicate hypersensitivity to hydralazine, coronary artery disease and mitral valvular rheumatic heart disease. Suspected coronary disease is separately addressed as a precaution; do not replace the formal coronary-disease contraindication with a generic “use cautiously” statement.

Neither selected single-ingredient label contains a boxed warning. Their lupus, ischemia and blood-dyscrasia warnings remain clinically important.

Headache, anorexia, nausea, vomiting, diarrhea, palpitations and tachycardia are reported. Other reactions include edema, hypotension, neuropathy, rash, rare hepatitis and serious blood dyscrasias; reliable frequencies are unavailable. Overdose may cause profound hypotension, arrhythmia, myocardial ischemia or shock. There is no specific antidote: urgent professional assessment and cardiovascular/renal support are central. Do not use legacy label gastric-decontamination text as a home-treatment instruction.

Use caution with MAO inhibitors. Combined potent parenteral antihypertensives, especially diazoxide, can cause profound hypotension; the labels call for continuous observation for several hours. Other combination regimens require individual titration of each medicine rather than automatic use of high hydralazine doses.

Oral food exposure increases plasma levels; changes in meal timing can affect response. The labels also note reduced pressor response to epinephrine, which matters to clinicians managing hemodynamic emergencies. These observations do not establish a fixed dose adjustment or a reason to withhold emergency care.

Human pregnancy studies are inadequate; animal developmental effects are reported. Use when expected maternal benefit justifies potential fetal risk, with an obstetric clinician selecting the appropriate protocol when relevant. Hydralazine is excreted in human milk; these labels provide no quantified infant exposure or outcome-based lactation conclusion. Do not equate that limited statement with a breastfeeding prohibition.

Pediatric regimens appear in the labels despite the absence of controlled safety/effectiveness trials. There is no separate geriatric dose algorithm in these selected labels; assess renal function, hypotension vulnerability, comorbidity and concomitant medicines when titrating. Preserve the distinction between described clinical experience and established trial evidence.

Use cautiously in advanced renal impairment; some injection patients require less than the usual dose. Hydralazine undergoes extensive hepatic metabolism and urinary metabolite excretion, but the labels supply no validated Child-Pugh or eGFR dosing schedule. Monitor pressure, adverse effects and renal status rather than inventing a universal adjustment.

Hydralazine directly relaxes vascular smooth muscle, predominantly arterioles; the precise mechanism is incompletely defined. Reduced vascular resistance increases heart rate and cardiac output. Reflex renin/aldosterone activity can promote sodium retention, explaining the need to review edema and combination therapy.

Oral peaks occur in 1–2 hours; apparent plasma half-life is about 3–7 hours and protein binding about 87%. Polymorphic acetylation produces wide variability: slow acetylators may have higher exposure and need lower doses. Hepatic metabolism and urinary metabolite elimination predominate. The injection label supplies a 10–80-minute average maximal pressure response but no additional route-specific pharmacokinetic data.

Check blood pressure and pulse during titration; closely monitor parenteral responses. The labels indicate CBC and ANA before and periodically during prolonged therapy, even without symptoms, and with fever, arthralgia, chest pain or unexplained malaise. A positive ANA requires benefit–risk assessment. Discontinue for clinically significant label-described blood dyscrasias. Assess renal involvement when lupus-like symptoms occur and investigate neuropathy.

Take oral doses regularly as prescribed and maintain consistent food timing. Report fainting, chest pain, persistent palpitations, joint pain, fever, malaise, rash, numbness or tingling promptly. Seek urgent care for severe chest pain or collapse. Do not change to an injectable regimen or escalate a resistant-hypertension dose without supervision.

Strides tablets are orange and marked with their strength; a 25-mg, 100-tablet bottle is NDC 64380-734-06. Baxter injection is a clear colorless 20-mg/mL solution in a 1-mL single-dose vial, NDC 43066-041-01; its 25-vial carton is NDC 43066-041-25. Generic tablet appearance can vary.

Selected tablets contain hydralazine hydrochloride 10, 25, 50 or 100 mg; injection contains 20 mg/mL for IM/IV use. Fixed-dose isosorbide dinitrate/hydralazine, compounded oral liquids and other injection presentations require separate product verification.

Store both selected products at 20–25°C. Tablets require a tight, light-resistant container and appropriate child-resistant closure. Use an injection vial immediately after opening; do not add it to infusion solution, and discard unused or discolored solution. Contact with metal can discolor the injection.