Labetalol Hydrochloride

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Cat Number

API0231620

CAS Number

32780-64-6

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Product Detail Description Scientific Support Customer Q&A

CAS Number

32780-64-6

EINECS

276-694-6

Storage

Store at room temperature

Synonyms

Labetalol HCL; Labrocol; ScH 15719W; AH 5158A; Ibidomide hydrochloride; Sch-15719W; 1GEV3BAW9J

Molecular Formula

C19H25ClN2O3

Molecular Weight

364.9

Smiles

CC(CCC1=CC=CC=C1)NCC(C2=CC(=C(C=C2)O)C(=O)N)O.Cl

Appearance

White or off-white crystalline powder

Melting Point

187-189℃

Boiling Point

552.7±50.0℃ at 760 mmHg

Relative Density

1.2±0.1 (Predicted)

General Description

Labetalol hydrochloride is a unique antihypertensive agent that combines non-selective beta-adrenergic blockade with selective alpha-1 adrenergic antagonism. It lowers blood pressure without causing reflex tachycardia. The drug is particularly useful in hypertensive emergencies and pregnancy-induced hypertension.

Mechanism of Action

Labetalol blocks beta-1 and beta-2 receptors in the heart and peripheral vasculature, reducing heart rate and cardiac output. Concurrent alpha-1 blockade produces arteriolar vasodilation, decreasing systemic vascular resistance. Unlike pure beta-blockers, this dual mechanism prevents unopposed alpha-mediated vasoconstriction. The ratio of beta to alpha blockade is approximately 3:1 orally and 7:1 intravenously.

Application

Labetalol is indicated for the management of hypertension, including hypertensive emergencies (via IV) and chronic essential hypertension (oral). It is the preferred agent for gestational hypertension and preeclampsia due to its safety profile during pregnancy. The drug also treats intraoperative hypertension and pheochromocytoma-related hypertension.

In a double‑blind randomized trial, 60 women with severe preeclampsia received three doses (20 minutes apart) of nifedipine, labetalol, or hydralazine. Nifedipine was most effective after a single dose (57.5% achieving ≥20% mean arterial pressure reduction), while hydralazine was most effective after three doses (111.3% of target reduction – an overshoot). Labetalol fell in between. The authors conclude that nifedipine is preferred when rapid single‑dose action is needed, but hydralazine is more effective when up to three doses can be given within 60 minutes.

Fig. 1 Dose required to reach target mean arterial pressure (MAP) in patients with severe preeclampsia treated with nifedipine, labetalol, and hydralazine. (Donel S, et al., 2023)

References

Donel S, et al. Effectiveness of nifedipine, labetalol, and hydralazine as emergency antihypertension in severe preeclampsia: a randomized control trial. F1000Res. 2023;11:1287.

Does Labetalol Hydrochloride require protection from light during storage?

Yes, it is photosensitive. Exposure to light can cause discoloration and degradation of the salicylamide moiety. Store in light-resistant containers, preferably amber glass.

What is the recommended storage temperature for Labetalol Hydrochloride?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate oxidative degradation and impurity formation.

Is Labetalol Hydrochloride hygroscopic, and how is this managed?

It is slightly hygroscopic. Under high humidity (>70% RH), it may absorb moisture and clump. Storage in tightly sealed containers with desiccant is recommended.

How is the impurity labetalol N-oxide monitored during stability?

This oxidative degradation product is quantified using a stability-indicating HPLC method, ensuring it remains within ICH limits throughout shelf life.