Naloxone (hydrochloride) 357-08-4

Product Overview

Naloxone hydrochloride is the mono hydrochloride salt of naloxone, supplied as a crystalline solid against a stated purity specification. Published pharmacology describes the molecule as an opioid receptor antagonist: it occupies opioid receptors and blocks agonist activity at them, which is the property that places it in receptor studies, analytical methods and reference collections. It is supplied as a characterised chemical for professional laboratory and development work.

The buyers who order it usually sit in one of four places: a pharmaceutical API development group characterising a salt form, an analytical or QC laboratory that needs a documented antagonist for method work, a receptor pharmacology group running antagonist arms, or a forensic and toxicology unit building a reference collection. Each of those groups asks a slightly different question, and the sections below are arranged so that all four are answered directly.

Buyers who source across several fine chemicals manufacturers tend to apply the same checklist to every compound: is the identity data complete, is the physical form workable at bench scale, and is the storage requirement something the facility can actually meet. This product answers those three questions up front, so the decision rests on technical grounds rather than on how polished the listing looks.

Comparing research chemicals suppliers usually comes down to how much is published before the order — salt form, formula weight, structural identifiers, solubility, and what happens to the material in transit. All of that is set out here, together with the practical notes that decide whether the compound fits a method you already run.

Specifications

Key Features

• Identity stated three ways. The CAS number, molecular formula and InChI key are all published, so a batch can be cross-checked against a method file or the incoming batch documentation without a second enquiry.
• A purity floor on the specification. The stated minimum is what a method file should cite, rather than a typical value that drifts between lots.
• A crystalline solid, not a gum or a flake. It weighs cleanly, transfers out of the vial without clinging to the walls, and dissolves predictably in DMF, DMSO, ethanol and buffered DMF.
• The storage condition published up front. A laboratory can check freezer space and receiving arrangements before the pack is dispatched, instead of discovering the requirement on the label.
• A record that stays stable. Teams maintaining a compound library of active pharmaceutical ingredients can register this material under its identifiers, so the entry survives a later change of pack size or source.
• Nothing important left to the batch report. Salt form, solubility and storage appear on the product, which is what buyers increasingly ask laboratory chemicals suppliers for at first contact.

Receptor Activity & Literature Context

In the pharmacological literature, naloxone hydrochloride is a competitive antagonist at opioid receptors. It binds the receptor without activating it and prevents agonist molecules from occupying the same site. That receptor-level behaviour is the reason the compound appears so consistently in published work on opioid-induced respiratory depression and acute opioid toxicity, and in the older literature on reversal of anaesthetic analgesic effects.

For teams working with active pharmaceutical ingredients, the practical value of a well-characterised antagonist is that it gives an assay a defined counterweight — a compound whose behaviour at the receptor is already documented, so an unexpected result can be traced to the method rather than to the standard. That is the role this material plays in binding studies, selectivity screens and analytical development, where the antagonist arm has to be as well documented as the agonist arm.

The structure and the salt form are unambiguous, which is why the compound also travels well as an analytical reference: it can be identified by retention time, mass transition or UV profile against a documented record, and the same identifier set carries between laboratories and between instruments.

What this product does not carry is equally deliberate. There is no dosing information, no guidance on administration and no synthetic route, because the material is supplied for laboratory and development work only. If your requirement sits outside that scope, it is better to say so at enquiry stage than after dispatch.

Applications

• Receptor binding and selectivity studies. This documented antagonist gives your assay a known activity baseline, and the crystalline solid is easy to weigh into the buffer system your protocol already uses.
• Analytical method development and validation. When you confirm identity by retention time, UV, or mass transition, you need a standard with fixed salt form and formula weight — both are published here.
• QC and reference collections. Labs that keep a small characterised library on hand use this compound as an identity check that holds across instruments and over time.
• Pharmaceutical API development. If you are characterising a pharmaceutical API salt form, use this hydrochloride as a documented material for solubility and stability work before the project moves further along.
• Forensic and toxicology reference shelves. Units that buy from research chemical suppliers for method calibration keep a characterised opioid antagonist available so a screen can be confirmed rather than merely flagged.
• Academic and contract research groups. A single study often needs a documented antagonist rather than a standing supply, and the specification here is detailed enough to write into your protocol or grant record.

Solubility & Solution Handling

1. Start with DMF when you need the highest working concentration. The documented figure is 5 mg/ml, which leaves headroom for most stock solutions prepared at bench scale.
2. For buffered work, use DMF:PBS at pH 7.2 in a 1:2 ratio. That system is documented at 0.3 mg/ml, so plan a more dilute working solution or a smaller volume than you would use in neat DMF.
3. DMSO is documented at 3 mg/ml and is the usual choice when a solution has to be held frozen between sessions and diluted into aqueous buffer at the point of use.
4. Ethanol gives 1 mg/ml, the lowest of the four, and suits methods that cannot tolerate DMF or DMSO in the injection solvent.
5. Label every solution with solvent, concentration and date. Methods that run for months are the ones where an unlabelled vial quietly becomes the weak link.
6. If your protocol specifies a solvent that is not on this list, ask before you order. It is the kind of question research chemicals suppliers field every week, and a short exchange now is cheaper than a mismatch at the bench later.

Storage & Stability

The material is stored at −20 °C. Stability is stated as five years or more under that condition, long enough that a pack bought for one campaign can serve the next, provided the storage discipline holds.

The usual failure mode is not the freezer set point but the handling around it. Sensitive active pharmaceutical ingredients lose assay value faster through repeated warming cycles, condensation on a cold vial and repeated opening of the same container than through the storage temperature itself. Weigh or aliquot what you need in one session, let the sealed container come to room temperature before opening it, and return the remainder to the freezer promptly.

Shipping is arranged at room temperature within the continental US; arrangements may differ elsewhere, because transit time and ambient conditions vary by route. If your facility has a receiving rule that requires a cold shipment regardless of route, say so at enquiry stage and we will confirm what can be arranged.

Keep a short log with the material — date received, storage location, date first opened. If a result is ever questioned, that log is what turns an ambiguity into an answer.

Ordering & Documentation

1. Tell us the quantity you need for the campaign and the date you need it by. Pack sizes and quantities are set per order rather than published here, so stating the amount is the fastest route.
2. Describe the project the pharmaceutical API is going into — development, analytical method work or reference collection — and tell us which documents your QA group will ask for. Additional analytical data, a batch-specific statement or a supplier questionnaire can all be discussed before the order is placed.
3. Confirm the destination and the end use. Regulatory status for opioid antagonists differs between countries, and we confirm the position for your destination before dispatch rather than after.
4. Agree the shipping route and delivery terms with your sales contact. Transit arrangements, payment terms and schedules are set per order and confirmed in writing at quotation stage.
5. If you already hold a record for this compound from another source, send it. Buyers who move between fine chemicals manufacturers for different compounds find it quicker to have the existing record matched against the current specification than to rebuild the file from scratch.
6. Ask your sales contact about sample availability if you need to qualify the material before a larger order. They can confirm what is possible for your destination and quantity.

Salt Form & Method Transfer

The salt you are ordering. This product is naloxone mono hydrochloride: one hydrochloride per naloxone molecule, written C19H21NO4·HCl with a formula weight of 363.8. The free base is the same molecule without that hydrochloride, so the two forms sit about 36.5 mass units apart. Almost every practical difference below follows from that one number.

Concentrations do not carry across. A method written as 1 mg/ml of naloxone base is not reproduced by weighing 1 mg/ml of the hydrochloride: the salt carries extra mass that is not naloxone, so the molar concentration at the same milligram figure is lower. Recalculate from the formula weight before the first weighing, and write the basis on the solution label so a later reader knows which form the stock was made from.

Solubility has to be re-established. The documented figures for this material are 5 mg/ml in DMF, 3 mg/ml in DMSO, 1 mg/ml in ethanol and 0.3 mg/ml in DMF:PBS at pH 7.2, all measured on the hydrochloride. A base method that ran in a different solvent, or at a different strength, needs its own check rather than an assumption. Buyers who compare laboratory chemicals suppliers for both forms usually find each form quoted with its own solubility set.

What changes on the instrument. In solution the hydrochloride dissociates, so an LC-MS method still reports the protonated naloxone ion. Retention time and peak shape can move, however, because the counter-ion alters the ionic strength and pH of the injected solution. If a method was validated on the base, run suitability — tailing, resolution and injection precision — on the salt before releasing results against it.

Purity basis. The ≥95% specification applies to the hydrochloride as supplied. If your specification is written on the base, or on a dried basis, say so at enquiry and we will confirm how the figure is calculated for your batch.

On receipt. Check that the label states the hydrochloride salt, then match CAS 357-08-4 and InChI key RGPDIGOSVORSAK-STHHAXOLSA-N against your record before the material is booked in. Incoming entries logged as plain “naloxone” are how a base record and a salt record end up merged in the same database.

On the purchase order. Put the salt form and CAS 357-08-4 on the order line. “Naloxone” on its own is ambiguous, and a correction after the paperwork is raised costs more time than writing the full name once.

Regulatory Status & Import Declarations

• Two separate questions. Whether naloxone hydrochloride is regulated where you are, and what you must declare to bring it in, are decided by different rules: the first by medicines or scheduling legislation in the destination country, the second by the import procedure at the port of entry. Settle both before the order is placed.
• Where the status comes from. In most markets the compound is an active pharmaceutical ingredient in prescription medicines, which is why it is usually handled as a licensed import rather than a general laboratory reagent. Some destinations schedule it as well; others regulate it only as a prescription substance. The position where it was manufactured does not carry over to where it is imported.
• Declaration item one: end use. Expect to describe the application in plain terms — receptor pharmacology, an analytical reference, method validation or pharmaceutical API development — and to name the facility, the responsible person and the site address receiving the goods.
• Declaration item two: parties and authorisation. The importer of record, the consignee and, where your jurisdiction requires one, the import permit, controlled-substance registration or licence number. Have that number ready at enquiry rather than after the goods are booked.
• Declaration item three: identity and quantity. Quote the wording on the batch documentation: CAS 357-08-4, naloxone mono hydrochloride, C19H21NO4·HCl, formula weight 363.8, with the pack breakdown in the units your broker uses. A declaration written as plain “naloxone” without the salt form is the most common reason a broker returns with a query.
• Documents your broker will want. A batch analysis report, a safety data sheet and a packing list travel with the shipment. Ask whether the safety data sheet has to be in a local language or a particular format before the goods move; that single question prevents most holds.
• Tariff classification. Harmonised-system classification and duty treatment are settled with your customs broker. What we provide is the product description and identity data your broker needs to classify the entry.
• If the authorisation is not in place yet. Tell us at enquiry stage. We would rather hold an order while a permit is obtained than have it stopped at the border, and the answer costs nothing to ask for.
• Where our advice stops. Domestic licensing and import law are a matter for your regulatory team. What we supply is the identity data, the batch documentation and the shipping paperwork that sit on your side of the file.

Quality Control & Inspection

Quality is the foundation of how we work. As a specialized enterprise serving the chemical and pharmaceutical sectors, we apply staged in-process checks and a final inspection against the agreed specification before packing, and we retain samples for reference. If you prefer an independent check, we are glad to coordinate with the third-party inspection agency you appoint. Shipments travel with their certificate of analysis, packing list and safety data sheet; any item that falls short of specification is investigated, then replaced or credited. Our team supports buyers across Europe, the Americas, Australia and Japan.

FAQ