Ciprofloxacin

Athanor · official

C₁₇H₁₈FN₃O₃ · 331.34 g/mol

IUPAC name: 1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-ylquinoline-3-carboxylic acid

Also called Cipro, fluoroquinolone

Drugs Rings

Open in Athanor

Drawn from its SMILES with RDKit

HazardsHarmful to aquatic life with long lasting effects

Names and identifiers

IUPAC name: 1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-ylquinoline-3-carboxylic acid
Synonyms: Cipro, fluoroquinolone, Ciprofloxacine
+ 36 more
Ciprobay, Ciprofloxacina, 1-Cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid, Ciprofloxacino, Ciprofloxacinum, 1-cyclopropyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid, Ciprocinol, Bacquinor, Cifloxin, Ciprodar, Otiprio, BAY q 3939, CPFX, BAYQ3939, 1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-ylquinoline-3-carboxylic acid, 1-Cyclopropyl-6-fluoro-4-oxo-7-(1-piperazinyl)-1,4-dihydro-3-quinolinecarboxylic acid, 1-CYCLOPROPYL-6-FLUORO-4-OXO-7-PIPERAZIN-1-YL-1,4-DIHYDROQUINOLINE-3-CARBOXYLIC ACID, Velmonit, NSC-758467, 5E8K9I0O4U, CIPRO IN DEXTROSE 5% IN PLASTIC CONTAINER, DTXSID8022824, BAY O 9867 FREE BASE, BAY-O-9867 FREE BASE, BAY-Q-3939, CIPRO IN SODIUM CHLORIDE 0.9% IN PLASTIC CONTAINER, 3-Quinolinecarboxylic acid, 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-, Bay 09867, CHEBI:100241, 3-Quinolinecarboxylic acid, 1,4-dihydro-1-cyclopropyl-6-fluoro-4-oxo-7-(1-piperazinyl)-, 1-Cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-yl-1,4-dihydro-quinoline-3-carboxylic acid, 1-cyclopropyl-6-fluoro-7-hexahydro-1-pyrazinyl-4-oxo-1,4-dihydro-3-quinolinecarboxylic acid, 1-Cyclopropyl-6-fluoro-7-(4-methyl-piperazin-1-yl)-4-oxo-1,4-dihydro-quinoline-3-carboxylic acid, Ciprofloxacin In Dextrose 5%, 1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-4-ium-1-ylquinoline-3-carboxylate, RefChem:6412
Molecular formula: C₁₇H₁₈FN₃O₃
Empirical formula: C₁₇H₁₈FN₃O₃
Molecular weight: 331.34 g/mol
Exact mass: 331.13322
CAS number: 85721-33-1
PubChem CID: 2764
Canonical SMILES: C1CC1N2C=C(C(=O)C3=CC(=C(C=C32)N4CCNCC4)F)C(=O)O
Isomeric SMILES: C1CC1N2C=C(C(=O)C3=CC(=C(C=C32)N4CCNCC4)F)C(=O)O
InChI: InChI=1S/C17H18FN3O3/c18-13-7-11-14(8-15(13)20-5-3-19-4-6-20)21(10-1-2-10)9-12(16(11)22)17(23)24/h7-10,19H,1-6H2,(H,23,24)
InChIKey: MYSWGUAQZAJSOK-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

Appearance: Faint to light yellow crystalline powder[1]
Solubility in water: In water, 30,000 mg/L at 20 °C[1]
3 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Water Solubility: approx 36 mg/ml @ 25 °C /Ciprofloxacin hydrochloride/ [1] Hazardous Substances Data Bank (HSDB)cites McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2001. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2001 (Plus Supplements)., p. 739
– Soluble in dilute (0.1N) hydrochloric acid; practically insoluble in ethanol [1] Hazardous Substances Data Bank (HSDB)cites Physicians' Desk Reference. 55th ed. Montvale, NJ: Medical Economics Co, p. 852 (2001)
–shown In water, 30,000 mg/L at 20 °C [1] Hazardous Substances Data Bank (HSDB)cites Nowara A et al; J Agric Food Chem 45: 1459-1463 (1997)
log P: log Kow = 0.28 (non-ionized)[1]
pKa: pKa = 6.09 (carboxylic acid group)[1]
2 values
Only one source reports it.
Value As written Source
–shown pKa = 6.09 (carboxylic acid group) [1] Hazardous Substances Data Bank (HSDB)cites Torniainen K et al; Int J Pharm 132: 53-61 (1996)
– pKa = 8.74 (nitrogen on piperazinyl ring) [1] Hazardous Substances Data Bank (HSDB)cites Torniainen K et al; Int J Pharm 132: 53-61 (1996)

Value	As written	Source
–	Water Solubility: approx 36 mg/ml @ 25 °C /Ciprofloxacin hydrochloride/	[1] Hazardous Substances Data Bank (HSDB)cites McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2001. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2001 (Plus Supplements)., p. 739
–	Soluble in dilute (0.1N) hydrochloric acid; practically insoluble in ethanol	[1] Hazardous Substances Data Bank (HSDB)cites Physicians' Desk Reference. 55th ed. Montvale, NJ: Medical Economics Co, p. 852 (2001)
–shown	In water, 30,000 mg/L at 20 °C	[1] Hazardous Substances Data Bank (HSDB)cites Nowara A et al; J Agric Food Chem 45: 1459-1463 (1997)

Value	As written	Source
–shown	pKa = 6.09 (carboxylic acid group)	[1] Hazardous Substances Data Bank (HSDB)cites Torniainen K et al; Int J Pharm 132: 53-61 (1996)
–	pKa = 8.74 (nitrogen on piperazinyl ring)	[1] Hazardous Substances Data Bank (HSDB)cites Torniainen K et al; Int J Pharm 132: 53-61 (1996)

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms: 24
Rings: 4
Aromatic rings: 2
Fraction sp³ carbons (Fsp3): 0.41
H-bond donors: 2
H-bond acceptors: 4 computed here · PubChem 7
Rotatable bonds: 3
TPSA (Å²): 74.6 computed here · PubChem 72.9
Formal charge: 0
XLogP3: -1.1 PubChem
Complexity: 571 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C61.62%
H5.48%
F5.73%
N12.68%
O14.49%

Isotope pattern

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P: 1.58 Crippen (Wildman and Crippen 1999)
log S (water solubility): -3 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.47 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 331.35
log P ≤ 5 (Crippen): 1.58
H-bond donors ≤ 5: 2
H-bond acceptors ≤ 10: 4

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Most widely reported: 102 company reports to ECHA. Source [2].

H412Harmful to aquatic life with long lasting effects (26.5% of reports)

Precautionary statements: P273, P501

Storage

Ciprofloxacin hydrochloride conventional tablets should be stored in tight containers at a temperature less than 30 °C, and protected from intense UV light. Extended-release tablets containing ciprofloxacin hydrochloride and base (Cipro XR) and extended-release tablets containing ciprofloxacin hydrochloride (ProQuin XR) should be stored at 25 °C, but may be exposed to temperatures ranging from 15-30 °C. Ciprofloxacin microcapsules for oral suspension and the diluent provided by the manufacturer should be stored at less than 25 °C and protected from freezing.[1]
Ciprofloxacin for oral suspension: Prior to reconstitution, store below 25 °C (77 °F). Protect from freezing. After reconstitution, store below 30 °C (86 °F). Protect from freezing. The suspension is stable for 14 days when stored in a refrigerator or at room temperature below 39 °C or 86 °F.[1]
Ciprofloxacin tablets USP: Store below 30 °C (86 °F) in a well closed container.[1]
Ciprofloxacin injection USP: Store in a cool place between 8 and 15 °C (46-59 °F) or at controlled room temperature (between 20 and 25 °C (68 and 77 °F). ... Protect from light and freezing.[1]

Safety data sheets on the supplier’s page: AbaChemScene, Hairui Chemical, Enamine.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

[1]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[2]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[3]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[4]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[5]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[6]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
[7]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
·Literature on PubChem

Data last updated 2026-10-14.